fungal infection in the intensive care unit

Fungal Infection in theIntensive Care Unit

PERSPECTIVES ON CRITICAL CAREINFECTIOUS DISEASESJordi Rello, MD., Series Editor

1. N. Singh and J.M. Aguado (eds.): Infectious Complications inTransplant Recipients. 2000. ISBN 0-7923-7972-1

2. P.Q. Eichaclcer and 1. Pugin (eds.): Evolving Concepts in Sepsisand Septic Shock. 2001. ISBN 0-7923-7235-2

3. J. Rello and K. Leeper (eds.): Severe Community AcquiredPneumonia. 2001. ISBN 0-7923-7338-3

4. R.G. Wunderink and 1. Rello (eds.): Ventilator AssociatedPneumonia. 2001. ISBN 0-7923-7444-4

5. R.A. Weinstein and M. Bonten (eds.): Infection Control in the ICUEnvironment. 2002. ISBN 0-7923-7415-0

6. R.A. Barnes and D.W. Warnock (eds.): Fungal Infection in theIntensive Care Unit. 2002. ISBN 1-4020-7049-7

Fungal Infection in the Intensive Care Unit

edited by

R.A. BARNES University ofWales College ofMedicine, Cardiff,

United Kingdom

D.W. W ARNOCK Centers for Disease Control and Prevention, Atlanta,

Georgia, USA

ISBN 978-1-4613-5333-1 ISBN 978-1-4615-0977-6 (eBook) DOI 10.1007/978-1-4615-0977-6

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Contents

Contributors VII

Preface ix

Epidemiology ofCandida Infections in the Intensive Care Unit 1North American Perspective

RANA A. HAJJEH AND G. MARSHALL LYON

Cross-Infection with Candida in the Intensive Care Unit 13European Perspective

JACQUES BILLE

Risk Factors for Candida Infection in the Intensive Care Unit 23North American Perspective

RHONDA V. FLEMING AND THOMAS J . WALSH

Risk Factors for Candida Infections in the Intensive Care Unit 45European Perspective

ROSEMARY A. BARNES

Laboratory Diagnosis of Fungal Infection in the Intensive Care Unit 55North American Perspective

CHRISTINE J. MORRISON

VI

Clinical Diagnosis of Fungal Infection in the Intensive Care Unit 105European Perspective

PAULG. FLANAGAN

Management ofCandida Infections in the Intensive Care Unit 129North American Perspective

JOHN E. EDWARDS, JR.

Management ofCandida Infections in the Intensive Care Unit 139European Perspective

NEIL SONI

Non-Candida Fungal Infections in the Intensive Care Unit 165North American PerspectiveMARCOS I. RESTREPO AND JOHN R. GRAYBILL

Non-Candida Fungal Infections in the Intensive Care Unit 181European Perspective

HILARY HUMPHREYS

Index 191

Contributors

Rosemary A. Barnes, MA, MSc, MD, MRCP, FRCPath,Senior Lecturer, Department of Medical Microbiology, University ofWales College of Medicine, and Honorary Consultant, UniversityHospital ofWales, Cardiff, UK.

Jacques Bille, MD,Professor and Head, Clinical Bacteriology Laboratory, Institut deMicrobiologie, Centre Hospitalier Universitaire Vaudois, Lausanne,Switzerland.

John E. Edwards, Jr., MD,Professor of Medicine, University of California Los Angeles School ofMedicine, and Chief, Division of Infectious Diseases, Research andEducation Institute, Harbor/UCLA Medical Center, Los Angeles,California, USA.

Paul G. Flanagan, MB ChB, MD, MRCPath,Senior Lecturer, Department of Medical Microbiology, University ofWales College of Medicine, and Honorary Consultant, UniversityHospital ofWales, Cardiff, UK.

Rhonda V. Fleming, MD,Fellow in Infectious Diseases, Hospital of Saint Raphael, Yale UniversitySchool ofMedicine, New Haven, Connecticut, USA.

VIII

John R. Graybill, MD,Professor ofMedicine, University of Texas Health Science Center at SanAntonio, and Division of Infectious Diseases, Audie L. Murphy VeteransAffairs Medical Center, San Antonio, Texas, USA.

Rana A. Ha.ijeh, MD,Chief, Epidemiology Unit, Mycotic Diseases Branch, Division ofBacterial and Mycotic Diseases, National Center for Infectious Diseases,Centers for Disease Control and Prevention, Atlanta, Georgia, USA.

Hilary Humphreys, MD, FRCPI, FRCPath,Professor, Department of Clinical Microbiology, Royal College ofSurgeons in Ireland, and Beaumont Hospital, Dublin, Ireland.

G. Marshall Lyon, MD,Fellow in Infectious Diseases, Department of Medicine, MassachusettsGeneral Hospital, Boston, Massachusetts, USA.

Christine J. Morrison, PhD,Chief, Diagnostics Development Unit, Mycotic Diseases Branch,Division of Bacterial and Mycotic Diseases,. National Center forInfectious Diseases, Centers for Disease Control and Prevention, Atlanta,Georgia, USA.

Marcos I. Restrepo, MD,Fellow in Infectious Diseases, Department of Medicine, University ofTexas Health Science Center, San Antonio, Texas, USA.

Neil Soni, MB ChB, MD, FRCA, FFICANZCA, FANZCA,Consultant in Intensive Care, Chelsea and Westminster Hospital,London, United Kingdom.

Thomas J. Walsh, MD, FACP, FCCP,Chief, Immunocompromised Host Section, Pediatric Oncology Branch,National Cancer Institute, Bethesda, Maryland, USA.

Preface

Fungal infections are an increasing problem in critically-ill patients andthese infections carry an attributable mortality that is much higher thancorresponding bacterial infections. In both Europe and North America,Candida infections predominate and much of this book concentrates on theepidemiology, risk factors, diagnosis and treatment of these infections.Particular reference is made to the cross-infection problems of Candidainfection and the importance of infection control and preventative measures.However, other fungal infections are increasingly being seen in critically-illpatients.Advances in the management of severely immunocompromised patients

have resulted in their improved survival. Increasingly, transplant recipients,persons with AIDS, and patients with severe neutropenia require intensivecare and the range of opportunist fungal pathogens in this group is wide. Inaddition, in many parts of North America, infections with endemic fungi,such as Histoplasma capsulatum and Blastomyces dermatitidis, may beencountered among patients in intensive care. A description of theseinfections is included.Establishing a robust diagnostic strategy in fungal infection is a problem

that continues to evade clinicians. The list of available antifungal agents,whilst growing, is more limited than the antibacterial repertoire.Consequently, a variety of strategies for the recognition and treatment offungal infection in critical care are employed. The evidence base for thesestrategies is discussed.This book is designed to offer a European and North American

perspective on each topic. There are many similarities in experience andclinical practice but also significant differences that we hope will stimulatefurther thought and study. We hope the book will be of interest to

x

intensivists, infectious disease specialists, medical microbiologists and allthose with an involvement in critical care. Progress in intensive caremedicine is resulting in a growing population of critically-ill patients at riskof fungal infection. Further improvements in survival will require amultidisciplinary approach.

ROSEMARY A. BARNESUniversity ofWales College ofMedicine, Cardiff, United Kingdom

DAVID W. WARNOCKCenters for Disease Control and Prevention, Atlanta, Georgia. USA

Chapter 1

Epidemiology of Candida Infections in the IntensiveCare UnitNorth American Perspective

RANA A. HAJJEH and G. MARSHALL LYONCenters for Disease Control and Prevention, Atlanta, Georgia, USA

Over the last two decades, the incidence of many fungal diseases in theUnited States has increased dramatically, mostly due to major advances inhealth care, as well as various demographic changes. These include aging ofthe population, the HIV epidemic, and the increasingly aggressive medicaltherapies available. Broad-spectrum antibiotics are more widely used thanever, especially among neutropenic and surgical patients in the intensive careunit (lCU). Potent cytotoxic chemotherapy, as well as more effectiveimmunomodulation therapy, has resulted in prolonged survival of cancerpatients and transplant recipients, but also in periods of severeimmunosuppression and increased risk for fungal infections. Dramaticchanges have also been achieved in neonatal care, leading to improvedsurvival of premature infants.As a result, overall rates of bloodstream infection (BS!) have increased

significantly, in particular those caused by Candida species. A number ofstudies from the Centers for Disease Control and Prevention (CDC) haverecently documented these trends. In the first, a review of National Centerfor Health Statistics (NCHS) records showed that deaths from fungalinfections were the seventh most common cause of infectious disease-relatedmortality in the United States, increasing more than three-fold between 1980and 1992 (1). A second review ofNCHS death records revealed that invasivecandidiasis and aspergillosis were the two specific diseases that accountedfor most of these deaths (2). In a third study, a review of NCHShospitalization data showed that, in 1994, fungal infections resulted in about30,000 hospitalizations, and accounted for the fourth highest annualpercentage increase (10%) in number of hospitalizations since 1980 (3). Areview of the CDC National Nosocomial Infections Surveillance (NNIS)

2 Chapter 1

system data found that the rate of nosocomial fungal infections almostdoubled between 1980 and 1990, and that Candida species accounted foralmost 80% of these infections (4). More recently, a study by Pfaller et a/.showed that species of Candida continued to be the fourth most commoncause of nosocomial BSI in the United States, and were responsible for 8%of all BSI in hospitals (5).Although it is likely that many of these infections are occurring in ICU

patients, few studies have focused on the epidemiology of Candidainfections in these units. In this chapter, we will review the various studiesthat have addressed the epidemiology of Candida infections in the ICU,focusing mainly on BSI, since these account for most of the morbidity andmortality attributable to Candida species in this health care setting. Issuesrelated to incidence of these infections, their risk factors and impact oncontrol measures, as well as factors that affect clinical outcome will bediscussed.

INCIDENCE OF CANDIDA INFECTIONS

Invasive Candida infections are not nationally reportable. As a result, mostpublished data on the incidence of these infections have been derived frominstitution-based studies. However, data from a few multicenter studies andpopulation-based studies have recently become available. Although thesestudies sometimes have similar designs, the denominators used to calculaterates of infection are often very different. This makes these studies difficultto compare and to use for trends analysis. These denominators may includeannual numbers of all hospitalized patients, patient days, or number ofcatheter days. Although population-based rates are useful to compareCandida infections to other community-acquired infections, they may bedifficult to interpret in a hospital setting. For critical care patients, ratesexpressed as number of days hospitalized in an ICU, or numbers of dayswith catheters (catheter days) may be the most useful.The increase in incidence of Candida infections has been noted in all

types of hospitals, from small community hospitals to large teachinginstitutions. Currently, Candida species rank as the fourth most commoncause of nosocomial BSI and the second most common cause of nosocomialurinary tract infections (6). According to data from the NNIS system, thenosocomial fungal infection rate increased from 0.9 to 6.6 per 1,000 patientsdischarged between 1980 and 1990, an increase of over seven-fold (6). In1976, the annual incidence of nosocomial infections caused by Candidaspecies was 0.5 per 10,000 patients discharged (7). In a more recent study,the incidence of nosocomial BSI among patients admitted to a surgical

1. Epidemiology ofCandida Infections in the Intensive Care Unit 3

intensive care unit (SICU) was found to be 26.7 per 1,000 admissions (8).Between 1980 and 1989, the incidence of candidiasis increased 2.7 timesfrom 1.4 to 3.8 per 1,000 admissions, according to data from the NationalHospital Discharge Survey (9). Disseminated candidiasis, a specificInternational Classification of Diseases (ICD-9) code, was noted to haveincreased II-fold to 0.15 cases per 1,000 admissions over the same timeperiod (9). The increase was largest among patients less than 15 years ofage; non-whites showed a disproportionately larger increase, 13- versus 10fold, compared with whites (9).This increasing trend in the incidence of candidiasis seems to have been

most marked during the 1980s, as noted in several other studies (10,11), andrates appear to have stabilized in the 1990s. Population-based surveillance,conducted in Atlanta and San Francisco during 1992 and 1993, showed thatthe overall incidence of candidemia was 8 cases per 100,000 population (12).Incidence rates in this study were significantly higher among neonates (466per 100,000), persons with cancer (71 per 100,000), and persons withdiabetes mellitus (28 per 100,000), than among the general population. Inaddition, major racial differences in rates of disease were noted: blacks hadtwice the annual incidence of white persons, with this difference being mostmarked among newborns (four-fold higher incidence in black infants). Asimilar population-based surveillance for candidemia, conducted between1998 and 2000, documented similar rates of disease at different sites withinthe United States (13). About 40% of cases occurred in ICU patients.The incidence of Candida BSI may now be decreasing in some

populations. A recent analysis of NNIS data, presented at the fourthDecennial International Conference on Nosocomial and HealthcareAssociated Infections, focused on ICU-related infections (14). The incidencetrend of Candida BSI was found to have decreased through the 1990s. Thepatients included in this surveillance were from ICUs and high-risknurseries. The decrease in the overall rate of BSI caused by Candida specieswas largely due to a decline in the incidence of C. albicans infections. Theincidence of infections caused by other Candida species in general hasremained the same, except for those caused by C. glabrata, which increasedduring the study period. The dramatic changes in critical care, as well as theincreased numbers of transplantation procedures during the 1980s, may havecontributed to the increasing incidence of all fungal infections during thatdecade. The introduction of azole drugs, particularly fluconazole, late in the1980s may have contributed to the stabilization in rates of disease in the1990s.

4 Chapter I

THE CHANGING DISTRIBUTION OF CANDIDASPECIES CAUSING BLOODSTREAM INFECTIONS

Candida albicans used to be the species responsible for the majority ofCandida BSI. However, the proportion of infections caused by C. albicanshas decreased over the last decade. In a population-based surveillance study,performed during 1992 and 1993, C. albicans accounted for 52% of cases ofcandidemia, followed by C. parapsilosis (21%), C. glabrata (12%), and C.tropicalis (10%) (12). Other large multicenter studies have identified similarpatterns of species distribution (5,15). However, the distribution of variousCandida species differs between age groups, as well as between differentpatient populations and ICUs (5,12,13,15). The National Epidemiology ofMycoses Survey (NEMIS), a study conducted in SICUs and neonatalintensive care units (NICUs) found that in the former, C. albicans was themost common organism (59%), followed by C. glabrata (16%), C. tropicalis(11%), C. parapsilosis (6%), and C. krusei (4%) (16). However, in NICUs,C. albicans (51%) and C. parapsilosis (47%) accounted for almost all of theinfections. These results are very similar to those derived by populationbased surveillance, where C. albicans was isolated from 53% and C.parapsilosis from 45% ofneonates (12).The species distribution also differs by country. A multicenter study from

Canada, conducted between 1992 and 1994, found C. albicans to be the mostcommon organism (69%), with small proportions due to the other species (c.parapsilosis, 10%; C. glabrata, 8%; C. tropicalis, 7%) (15). The differencesin species distribution may be due to the different medical and surgicalpractices in different institutions and countries. For example, routinechemoprophylaxis with fluconazole of neutropenic patients andhematopoietic stem cell transplant (HSCT) recipients has led to changes inthe epidemiology of candidemia in these patient populations. A recent studyfrom Seattle documented the effect of this practice on the infecting Candidaspecies (17). Non-albicans species of Candida caused the majority ofcandidemia cases following HSCT, the most common being C. glabrata(47%) and C. parapsilosis (23%). A similar trend was detected amongleukemic patients in Houston (18).


SPECIAL CONSIDERATIONS IN SELECTIVEINTENSIVE CARE UNITS

Neonatal intensive care units

As with other critical care patients, the incidence of candidemia amongNlCU patients has increased. Through the 1980s and early 1990s bothnational surveillance programs and single institution studies demonstratedseveral fold increases in the incidence of invasive candidiasis (6,16,19). Inone institution, the rate of candidemia increased from 2.5 cases per 1,000patients between 1981 and 1985, to 28.5 cases per 1,000 patients between1991 and 1995 (19). The incidence of candidemia increased proportionatelyamong very low birth weight infants and other neonates admitted to theNlCU (19). The increased rates of candidemia detected among NlCUpatients may be related to the improved survival of low-birth-weight infantsand the resultant longer hospitalizations.Differences in the incidence of candidemia between white and black

infants have recently been reported, with rates among black infants beingtwo to three times higher than among white infants (12,13). Thesedifferences may be due to the higher prevalence of prematurity among blacknewborns. Candidemia among neonates is predominantly caused by twospecies, C. albicans and C. parapsilosis. During the 1970s and early 1980s,C. albicans was responsible for the majority of candidemia infections inNlCU patients. However, in the late 1980s and early 1990s, the proportion ofinfections caused by C. parapsilosis gradually increased (19-21). Theseinfections are usually associated with various common lCU practices, suchas total parenteral nutrition, central venous catheters, and antibiotics (22,23).Nosocomial outbreaks of C. parapsilosis infection have occasionallyoccurred in NlCUs, and have often been traced to a contaminated medicineor intravenous solution, or to transmission via colonized health care workers(24-26).

Surgical intensive care units

The NEMlS study is probably the largest to have specifically evaluatednosocomial fungal infections in SICU patients (16,27). The study wasconducted in seven SICUs, belonging to six different institutions, over an 18month period, during which candidemia developed at an average rate of 9.8per 1,000 admissions (range: 2.9-15.8), or 1 per 1,000 patient-days (range:0.3-1.7) (16,27). The different rates of candidemia among the variousinstitutions are likely to have been due to differences in patient populations,infection control practices and medical management. The most common

6 Chapt'er 1

species isolated was C. aibicans (48%), followed by C. giabrata (24%), C.tropicalis (19%) and C. parapsilosis (7%) (16,27).A population that deserves special attention is bum patients. Patients who

have suffered third degree bums to a large area of their body surface areparticularly susceptible to infections caused by Candida species, which oftencolonize the skin and mucocutaneous surfaces. A study by Ekenna et ai.found that 8.4% of patients surveyed over a 42 month period in a large bumunit developed candidemia (28). Having a positive bum wound culture for aspecies of Candida was associated with increased risk of candidemia (28).Multivariable analysis showed that the total number of blood cultures whichgrew pathogens, bum size, duration of hospitalization, and age of patientwere associated both with candidemia and increased mortality, and that bumsize was the best clinically useful predictor of subsequent candidemia andmortality.

TRANSMISSION OF INFECTION AND RISK FACTORS

Candida species are normal commensals of humans, being commonly foundon the skin, in the gastrointestinal tract, and in the female genital tract (29).The majority of cases of nosocomial candidemia occur sporadically, andmost are due to endogenous infection, i.e. the strain causing the BSl isusually the same as that colonizing the patient's skin, gastrointestinal tract,or urogenital tract. The gastrointestinal tract has long been known to be apotential source for entry of Candida species into the bloodstream (30).Recently, as part of the NEMlS study, molecular subtyping of a largenumber of isolates was conducted, using a variety of typing methods (pulsedfield gel electrophoresis, restriction enzyme analysis, and electrophoretickaryotyping) (31). Most isolates had a unique strain type, suggestingendogenous infection rather than nosocomial transmission. The role ofcatheters in transmission of candidemia has been a subject of controversy,but they mostly serve as a route of entry for cutaneous organisms. A recentstudy suggests that local thrombophlebitis at the skin site of catheter entrymay be the cause of candidemia in some cases (32).Various risk factors have been associated with an increased risk of

candidemia. These can be divided into host factors, such asimmunosuppression due to various conditions, and hospitalization-relatedfactors, such as central venous catheters, excessive antibiotic use, andsurgical procedures. Both categories of risk factors are commonly presentamong leU patients. The widespread use of antibiotics, leading toovergrowth of Candida species in the gastrointestinal tract, and use ofmultiple intravascular devices, including catheters and presssure monitoring


devices, are major predisposing factors. Other factors include cytotoxictherapy (leading to neutropenia, as well as loss of integrity of thegastrointestinal tract), abdominal surgery, and other immunosuppressiveconditions. Previous colonization by Candida species has been found to beindependently associated with an increased risk of candidemia in manystudies (10,17,33,34). The extent of colonization, as expressed by number ofsites colonized, has sometimes been helpful in predicting invasive Candidainfections in critically-ill surgical patients (34).Many outbreaks ofCandida infection have been reported in the literature,

although these are likely to represent only a small proportion of the overallburden of the disease (16). However, the various investigations that havebeen conducted during or following these outbreaks have significantlyincreased our understanding of the epidemiology of these infections.Outbreaks of candidiasis are usually due to transmission within the hospitalenvironment, either from health care workers, or to the various proceduresthat facilitate entry of the organisms intravascularly.Risk factors for candidemia may also differ by species. For example,

although central venous catheters and total parenteral nutrition have beenassociated with increased risk for candidemia in general, they areparticularly important for infections with C. parapsilosis (35-37). This maybe due to the propensity of this organism to proliferate in highconcentrations of glucose and lipids and to adhere to prosthetic devices (38).Risk factors also differ by patient population. A recent sub-analysis of theNEMIS study examined risk factors for candidemia among neonates inNICUs, and found that in addition to some common risk factors (such ascentral venous catheters, parenteral nutrition and shock), low gestational age,H2 blockers and low APGAR scores were associated with increased risk ofcandidemia (39).

MORBIDITY AND MORTALITY OF CANDIDEMIA

It is very difficult to ascertain the mortality and morbidity solely attributableto invasive Candida infections, since most patients who develop theseinfections, especially in ICUs, are quite sick prior to onset of candidemia.Population-based studies have detected crude mortality rates of 29% (12)and 38% (13). However, mortality rates reported in other studies haveranged from 30 to 60%, with the higher rates observed among high riskpatients from select referral institutions (10,15,34). One study estimated theattributable mortality of candidemia at 38% (10). C. albicans seems to beassociated with higher mortality rates (17,40,41).

8 Chapter 1

Poor outcome from candidemia, as defined by death or persistentinfection, has been associated with various factors, depending on the groupsstudied. Among cancer patients, higher APACHE scores, visceraldissemination, receiving steroids and persistent neutropenia were associatedwith a poor outcome (42). Other studies found a correlation betweenmultiple organ failure and candidemia in patients in SICUs and other ICUs(43,44). The recent NEMIS study of candidemia in SICU patients identifiedan attributable risk of mortality of only 7.7%, with independent risk factorsthat included older age and more severe underlying illness (such as shock,acute respiratory distress syndrome, and higher disease severity score) (45).In neonates, candidemia may be associated with other complications,including Candida meningitis (46) and retinopathy of prematurity (47).Very few studies have looked at the increased hospitalization costs due to

candidemia, but a recent analysis of national data from the Healthcare Costand Utilization Project found that patients with candidemia stayed in thehospital an average of 34 days longer than patients who did not develop theinfection (48). In addition, based on an annual incidence of candidemia inthe United States of 2 per 100,000, this study estimated that direct annualhospital charges due to candidemia exceeded $281 million.

PREVENTION

Although many studies have identified risk factors for candidemia, few ofthese factors are preventable or potentially modifiable. The only preventionmeasures shown to be effective have been in the setting of outbreaks, andhave usually consisted of improved hygiene and hand washing techniquesamong health care workers, or removal of a contaminated common source ofinfection. Currently, prophylaxis with fluconazole is only recommended foruse among selected leukemia or HSCT patients (49,50). Extending suchrecommendations to critically-ill patients in ICUs would be difficult toimplement and not very cost-effective, unless further studies identifyadditional risk factors to better define those patients who might benefit fromsuch an approach. Fluconazole prophylaxis does appear to be effective insome critically ill, non-neutropenic patients. A recent study foundprophylaxis with fluconazole (400 mg per day) to be effective in selectedhigh-risk surgical patients, such as those with recurrent gastrointestinalperforations or anastomotic leakages (51). Another recent study found that asimilar regimen of fluconazole prophylaxis decreased the incidence of fungalinfections in high-risk SICU patients (52). However, these patients tended tobe older and had a higher incidence of recent surgery and chronic conditions,such as diabetes mellitus and liver dysfunction. Because chemoprophylaxis


may be associated with development of antifungal drug resistance, as well aswith side effects related to drug toxicity, clinicians should be careful aboutimplementing such an approach in the ICU.Improving our understanding of the transmission of, and risk factors for,

candidemia is very important both for the management and for theprevention of these invasive and highly morbid infections. By defining highrisk groups in the ICU, we will be able to better target those patients whomay benefit from chemoprophylaxis and other prevention measures. Therecent development of improved molecular subtyping methods for species ofCandida will be very helpful in achieving these goals and clarifying theepidemiology of candidemia in the ICU (53).

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10 Chapter 1

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26. Huang YC, Lin TY, Leu HS, et al. Outbreak of Candida parapsilosis fungemia inneonatal intensive care units: clinical implications and genotyping analysis. Infection1999;27:97-102.

27. Rangel-Frausto MS, Wiblin T, Blumberg HM, et al. National epidemiology of mycosessurvey (NEMIS): variations in rates of bloodstream infections due to Candida species inseven surgical intensive care units and six neonatal intensive care units. Clin Infect Dis1999;29:253-8.

28. Ekenna 0, Sherertz RJ, Bingham H. Natural history of bloodstream infections in a bumpatient population: the importance of candidemia. Am J Infect Control 1993;21: 189-95.

29. Odds Fe. Candida and candidosis. 2nd edn. London: Bailliere Tindall, 1988.


30. Krause W, Matheis H, Wulf K. Fungaemia and funguria after oral administration ofCandida albicans. Lancet 1969; I:598-9.

31. Pfaller MA, Jones RN, Doem GV, et al. International surveillance of bloodstreaminfections due to Candida species: frequency of occurrence and antifungalsusceptibilities of isolates collected in 1997 in the United States, Canada, and SouthAmerica for the SENTRY Program. The SENTRY Participant Group. J Clin Microbiol1998;36: 1886-9.

32. Benoit D, Decruyenaere J, Vandewoude K, et al. Management of candidalthrombophlebitis of the central veins: case report and review. Clin Infect Dis1998;26:393-7.

33. Richet HM, Andremont A, Tancrede C, Pico JL, Jarvis WR. Risk factors for candidemiain patients with acute lymphocytic leukemia. Rev Infect Dis 1991;13:211-5.

34. Pittet D, Monod M, Suter PM, Frenk E, Auckenthaler R. Candida colonization andsubsequent infections in critically ill surgical patients. Ann Surg 1994;220:751-8.

35. Solomon SL, Alexander H, Eley JW, et al. Nosocomial fungemia in neonates associatedwith intravascular pressure-monitoring devices. Pediatr Infect Dis 1986;5:680-5.

36. Solomon SL, Khabbaz RF, Parker RH, et al. An outbreak of Candida parapsi/osisbloodstream infections in patients receiving parenteral nutrition. J Infect Dis1984; 149:98-1 02.

37. Weems JJ, Chamberland ME, Ward J, et al. Candida parapsi/osis fungemia associatedwith parenteral nutrition and contaminated blood pressure transducers. J Clin Microbiol1987;25: I029-32.

38. Weems J1. Candida parapsi/osis: epidemiology, pathogenicity, clinical manifestations,and antimicrobial susceptibility Clin Infect Dis 1992;14:756-66.

39. Saiman L, Ludington E, Pfaller M, et al. Risk factors for candidemia in neonatalintensive care unit patients. The National Epidemiology of Mycoses Survey study group.Pediatr Infect Dis J 2000; 19:319-24.

40. Goodrich JM, Reed EC, Mori M, et al. Clinical features and analysis of risk factors forinvasive candidal infection after marrow transplantation. J Infect Dis 1991; 164:731-40.

41. Slavin MA, Osborne B, Adams R, et al. Efficacy and safety of fluconazole prophylaxisfor fungal infections after marrow transplantation-a prospective, randomized, doubleblind study. J Infect Dis 1995;171: 1545-52.

42. Anaissie EJ, Rex JH, Uzun 0, Vartivarian S. Predictors of adverse outcome in cancerpatients with candidemia. Am J Med 1998;104:238-45.

43. Marshall JC, Christou NV, Horn R, Meakins JL. The microbiology of multiple organfailure. The proximal gastrointestinal tract as an occult reservoir of pathogens. Arch Surg1988;123:309-15.

44. Voss A, Ie Noble JL, Verduyn Lunel FM, Foudraine NA, Meis JF. Candidemia inintensive care unit patients: risk factors for mortality. Infection 1997;25:8-11.

45. King MD, Blumberg HM, Soucie M, et al. Mortality due to Candida bloodstreaminfections in the surgical intensive care unit. In: Abstracts of the 37th IDSA Conference,1999; abstract 289, p.90.

46. Huttova M, Hartmanova I, Kralinsky K, et al. Candida fungemia in neonates treated withfluconazole: report of forty cases, including eight with meningitis. Pediatr Infect Dis J1998;17:1012-5.

47. Mittal M, Dhanireddy R, Higgins RD. Candida sepsis and association with retinopathyof prematurity. Pediatrics 1998; I01 :654-7.

48. Rentz AM, Halpern MT, Bowden R. The impact of candidemia on length of hospitalstay, outcome, and overall cost of illness. Clin Infect Dis 1998;27:781-8.

12 Chapter 1

49. Goodman JL, Winston OJ, Greenfield RA, et al. A controlled trial of fluconazole toprevent fungal infections in patients undergoing bone marrow transplantation N Engl JMed 1992;326:845-51.

50. Rex JH, Walsh TJ, Sobel JD, et al. Practice guidelines for the treatment of candidiasis.Infectious Diseases Society of America. Clin Infect Dis 2000;30:662-78.

51. Eggimann P, Francioli P, Bille J, et al. Fluconazole prophylaxis prevents intra-abdominalcandidiasis in high-risk surgical patients Crit Care Med 1999;27: I066-72.

52. Pelz RK, Hendrix CW, Swoboda SM, et al. Double-blind placebo-controlled trial offluconazole to prevent candidal infections in critically ill surgical patients. Ann Surg2001;233:542-8.

53. Reiss E, Tanaka K, Bruker G, et al. Molecular diagnosis and epidemiology of fungalinfections. Med Mycol 1998;36(Suppl 1):249-57.

Chapter 2

Cross-Infection with Candida in the Intensive CareUnitEuropean Perspective

JACQUES BILLEUniversity Hospital, Lausanne, Switzerland

In the hospital setting, and especially in confined busy areas, such as theintensive care unit (lCU), cross-infections are an everyday concern.Theoretically, the main mechanisms of acquisition of cross-infections areidentical for almost all kinds of nosocomial infectious agents, namely: directpatient-to-patient transmission; transmission from a colonized or infectedpatient to a recipient via a third person, generally a health care worker(HCW); transmission from a colonized or infected patient to another patientvia a vehicle, usually a medical device; more or less simultaneoustransmission to two or more patients from a common source, such ascontaminated air (Aspergillus species), water (Legionella species), orintravenous (IV) infusions (Serratia species). This last mechanism is notstrictly a cross-infection implying necessarily an index case. An additionalcomplication in the case of infection with species of Candida derives fromtheir status as opportunistic pathogens. Candida species can be carriedasymptomatically by the index patient as a commensal, but nonethelesscause a severe infection in a recipient patient with impaired host defenses.The opposite scenario can also occur, rendering the investigation of crossinfections caused by opportunistic pathogens, such as Candida species,much more complicated than those caused by true pathogens such asMycobacterium tuberculosis or Legionella species.Reports on Candida cross-infections are not easy to interpret, because the

concurrent emergence of different strains belonging to the same species, andsimulating an outbreak, cannot always be convincingly excluded byappropriate discriminatory sub-specific strain typing techniques (1).Intensive care patients are at high risk for cross-infections because they

are often cared for in non-individual rooms, they require numerous nursing

14 Chapter 2

care interventions, they are equipped with multiple medical devices (IVlines, intubation tube, urinary catheter, etc.), often for prolonged periods, andthey are often severely ill and immunocompromised. In addition, manyfactors place them at risk for colonization by Candida species, such asbroad-spectrum antibiotics and IV lines.The risk and mechanisms of acquisition of Candida cross-infections vary

according to: the ecology and epidemiology of different species ofCandida;the type of patients at risk (neonates, medical ICU patients, surgical ICUpatients, bum patients); and the standard of care, infection control measuresand antimicrobial use policies (especially for azole antifungal prophylaxis orpreemptive antifungal therapy) at individual institutions.Almost all Candida species of clinical relevance (c. albicans, C.

glabrata, C. tropicalis, C. parapsilosis, C. krusei, C. guilliermondii, C.lusitaniae, C. dubliniensis) have a worldwide distribution, and have beenisolated from a range of sources in the environment (2). In humans, Candidainfections are generally considered to be endogenous in origin, mostly fromthe digestive tract, but also from the skin, oropharynx and female genitaltract. Most species of Candida have been isolated from these endogenoussites, C. albicans being the most predominant (isolated from up to 70% ofhealthy persons in different sites). C. tropicalis is ranked second to C.albicans in the oropharynx, and C. glabrata second in the gastrointestinaltract (3).Interestingly, C. albicans, while still the most prevalent Candida species

recovered from both healthy and sick persons, has been proportionally lessfrequently isolated from various environmental sources than many otherspecies. Accordingly, proportionally more outbreaks of hospital infections ortrue cross-infections have been ascribed to several non-albicans species ofCandida than to C. albicans.C. albicans is still responsible for a large proportion of nosocomial yeast

infections observed in the ICU setting. However, other species have eitheremerged under the pressure of antifungal drug prophylaxis (c. glabrata, C.krusei), or in association with special host factors. C. tropicalis has beenassociated with oncologic patients receiving chemotherapy (4); C. glabratais predominant in elderly patients with underlying diseases of the intestinalor urinary tracts (5); C. parapsilosis has been associated with intravasculardevices, monitoring equipment, or parenteral nutrition or therapy (6,7).Other less common species that have emerged more recently include C.lusitaniae, C. lipolytica, and C. dubliniensis.The following sections will review the outbreaks and episodes of cross

infections due to Candida species that have been described in the ICUsetting or among critical care patients during the last 20 years, according tothe different species involved.

2. Cross-Infection with Candida in the Intensive Care Unit

CANDIDAALBICANSINFECTIONS

15

The major reported outbreaks or clusters of cross-infections due to C.albicans among ICU patients are listed in Table 1. Wherever possible,outbreaks and cross-infections have been differentiated based on informationprovided in the reports concerned (8-20). All involved 15 or fewer patientsand occurred most frequently in neonatal ICUs (NICUs). This could berelated to the intensive nature of the care required by these patients, and tothe risk of yeast carriage from the digestive tract.

Table 1. Outbreaks or clusters ofCandida albicans cross-infections in ICUs

Year Type N Site Unit Source Typing Time Ref.method course

1983-4 CI 13 Blood ICU HCW Phenotypic 9m 81981 CI 12 Blood (2) NICU HCW Phenotypic 6m 91986 CI? 7 Blood NICU NO REA 7m 10NO CI 4 Blood NICU NO REA 4w II1990 0 3 Blood NICU TPN REA 5w 121992 CI 14 Mouth, skin NICU IPC? Phenotypic 4m 131992 CI 10 Blood (9) SICU HCW REA 15 d 141991 CI 7 Blood (4) NICU HCW RFLP 15 d 151989 0 15 Wound SICU HCW RFLP 12m 161990 0 4 Blood (I) NO IA PFGE 15 d 171984 NO 3 Blood NICU HCW? RFLP 3m 18NO CI 5 Blood (4) NICU HCW Phenotypic 30 d 191996-7 0 3 Spine OR HCW PFGE 40d 20CI, cross-infection; HCW, hands of health care workers; lA, intravenous anesthetic agent;IPC, interpersonal contact; N, number; NO, not documented; 0, outbreak; OR, operatingroom; PFGE, pulsed field gel electrophoresis; REA, restriction endonuclease analysis; RFLP,restriction fragment length polymorphism analysis; TPN, total parenteral nutrition andretrograde medication fluid

The major site of documented infection was the blood (in 77% ofepisodes), but in some instances, post-operative wounds were involved(16,20). In the majority of cases, the suspected or proven source, or vehicleof transmission, was the hands of health care workers (HCWs), especiallywhere true cross-infections occurred.A range of strain typing methods was used to characterize and compare

the isolates recovered from patients with those obtained from the suspectedvehicle of transmission. Generally, one or more molecular typing methodswere used, and often a combination of procedures were employed toestablish the degree of genetic relatedness or identity between strains. Insome of the older reports, due to a lack of molecular tools, only phenotypictyping methods were used.

16 Chapter 2

The time course of episodes varied from two weeks to several months(median 3 months), illustrating the difficulty of detecting outbreaks andclusters of cross-infections.

CANDIDA PARAPSILOSIS INFECTIONS

Table 2 lists the outbreaks and clusters of cross-infections caused by C.parapsilosis that have been reported among ICU patients (6,7,21-26). UnlikeC. albicans episodes, true cross-infections have been documented onlyrarely. Most C. parapsilosis outbreaks have been linked to nosocomialacquisition via various medical devices, particularly IV catheters and/or IVhyperalimentation (6,7,21). This species is known to proliferate in highglucose concentrations, and also to form biofilms on prosthetic materials(27). Other reported vehicles include pigeon guano (28). Three documentedepisodes of cross-infection involving several patients were related to handcarriage by HCWs (23,25,26). In fact, the route of acquisition of C.parapsilosis is complex; potential reservoirs include colonized or infectedpatients, hospital personnel and the inanimate' hospital environment. Inneonates, particularly those with delayed enteral feeding, gastrointestinaltract colonization by C. parapsilosis is significantly elevated (20%) (29). Ofnote, two episodes of pseudo-outbreaks due to C. parapsilosis, involvingcontamination of a solution and of an incubator used in microbiologylaboratories, have been reported (22,24).

Table 2. Outbreaks or clusters ofCandida parapsilosis cross-infections in ICUs

Year Type N Site Unit Source Typing Time Ref.method course

1981 0 5 Blood NO MO NO 2m 61982-3 0 8 Blood NICU MO NO 14m 71983-5 0 12 Blood PICU MO? NO 21 m 211985 PO NO Blood NO Phenotypic 6w 22NO CI 5 GI tract BMT HCW REA 7m 23NO PO 5 NO OR REA,RFLP 20 d 241994 CI 6 Blood BMT HCW EK 2m 251994 CI? 17 Blood NICU HCW? EK 5m 26BMT, bone marrow transplantation unit; CI, cross-infection; EK, electrophoretic karyotyping;HCW, hands of health care workers; MO, medical devices; N, number; NO, not documented;0, outbreak; PICU, pediatric intensive care unit; PO, pseudo-outbreak; REA, restrictionendonuclease analysis; RFLP, restriction fragment length polymorphism analysis

2. Cross-Infection with Candida in the Intensive Care Unit

INFECTIONS WITH OTHER CANDIDA SPECIES

17

Occasionally, outbreaks or clusters of cross-infections have been describedin ICUs caused by other less common species of Candida (Table 3) (11,3035). Remarkably, C. glabrata, although the second most important species ofCandida in many institutions, has been involved in only one episode ofprobable cross-infection. This involved more than 20 leukemic patients (11).C. lusitaniae and C. guilliermondii have also been implicated onlyoccasionally as agents of cross-colonization (33) or as agents of a pseudooutbreak (34) involving 17 neonates.

Table 3. Outbreaks or clusters of cross-infections in ICUs caused by species other than C.albicans or C. parapsilosis

Year Sp. Type N Site Unit Source Typing Time Ref.method course

1988-9 I CI? 23 Blood LU ND REA 15 m II1988 2 0 8 Wound OR HCW REA 2 m 30,

311988 2 CI ? 6 Blood NICU HCW? None 5 m 32ND 3 CI,O 5 SU BMT HCW? REA 7 m 331991 4 PO 17 Blood NICU ND 3 w 34ND 5 CI? 15 Blood BU HCW? None 84 m 35Sp.: I, C. glabrata; 2, C. tropicalis; 3, C. lusitaniae; 4, C. guil!iermondii; 5, C. rugosaBMT, bone marrow transplantation unit; BU, bums unit; CI, cross-infection; HCW, hands ofhealth care workers; LU, leukemia unit; N, number; ND, not documented; NICU, neonatalintensive care unit; 0, outbreak; OR, operating room; PO, pseudo-outbreak; REA, restrictionendonuclease analysis; SU, stool, urine

USE OF STRAIN TYPING METHODS TO INVESTIGATECANDIDA CROSS-INFECTION

In addition to the classic modes of acquisition of nosocomial infections(hospital environment, food or water supply, medical devices, parenteralnutrition), Candida infections can be passed from patient to patient byHCWs. Several studies have demonstrated that the proportion of HCWscarrying Candida species on their hands is important (36,37). At the sametime, compliance in hand washing is far from ideal, being around 50%among nurses and 30% among physicians in a recent study (38). Indeed,HCWs have been implicated in a sizeable number of cross-infectionepisodes due to several species ofCandida (Tables 1-3). In order to establisha causal relationship, sub-specific strain typing of isolates from patients, andfrom the hands ofHCWs or from environmental surfaces is essential.

18 Chapter 2

As illustrated in Tables 1-3, many typing procedures have been applied toseveral Candida species over the last 20 years. Phenotypic methods (such asbiotyping and resistotyping) have now been replaced by molecularprocedures. An ideal typing method should be able to type every isolate, behighly discriminatory, reproducible, rapid and inexpensive. A completereview of the molecular typing methods that have been applied to Candidaspecies is beyond the scope of this chapter, but the interested reader can findexcellent accounts elsewhere (39-41). Several molecular typing procedureshave been used to distinguish strains of Candida species: these includegenomic DNA digestion profiles, electrophoretic karyotyping (EK) (42),randomly amplified polymorphic DNA (RAPD) analysis (43), and Southernblot hybridization with repetitive DNA probes (44-46).These molecular typing methods have confirmed that the predominant

source ofCandida infection is endogenous acquisition via colonization of themucosal surfaces, that C. albicans is clonal, and that patients usually carry aunique strain. These methods have also documented episodes of exogenousCandida infections linked to hospital workers and/or environmental sources(47).More recently, several multicenter studies have looked at the

reproducibility and discriminatory power of molecular typing methods asapplied to isolates of different species of Candida (48-49). Voss et al. (48)examined three methods (PCR fingerprinting, EK, and restrictionendonuclease analysis of genomic DNA [REA] using pulsed field gelelectrophoresis), previously validated for C. albicans (50), for discriminatorypower with seven Candida species. They found that only a combination ofmethods was sufficient to obtain optimal strain delineation, and then only forC. tropicalis isolates. An important conclusion of this study was that atyping method, even though validated for a given Candida species, cannot beused blindly for other species. In particular, species-specific restrictionenzymes and primers should be carefully selected and used only aftervalidation. Espinel-Ingroff et al. (49) conducted an evaluation of 10 isolateseach of five different Candida species in three separate laboratories, usingEK and different REA protocols. Based on reliability, efficiency andsensitivity, the utility of the methods evaluated was again species- andrestriction enzyme-dependent, with EK proving generally superior. Theauthors concluded that standardized testing guidelines, such as thoseproposed for typing ofMRSA or enteric pathogens, were necessary.The practicality of current typing methods for Candida species was

discussed at a recent workshop on diagnosis and typing of nosocomial fungalinfections (51). It was concluded that results of typing methods using gelscan be difficult to interpret and that PCR-based methods lack reproducibility.

2. Cross-Infection with Candida in the Intensive Care Unit 19

This report highlights the need to develop uniform criteria for definingstrains as identical or different.Taking these limitations into account, it is clear that some of the methods

used in reported episodes of outbreaks or cross-infections are far fromoptimal, and some conclusions may be inexact. Nonetheless, it is striking tocontrast the high frequency of Candida colonization or carriage among acutecare patients and HCWs with the limited number of outbreaks or crossinfections reported. This suggests that all Candida isolates or clones may notcarry the same pathogenic potential, and that future research should targetpathogenicity or virulence factors. Strict observation of infection controlmeasures, particularly hand washing, should help to limit the number ofCandida cross-infections.

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2. Mok WY, da Silva MSB. Mycotlora of the human dermal surfaces. Can J Microbiol1984;30: 1205-9.

3. Odds Fe. Candida and candidosis, 2nd edn. London: Bailliere Tindall, 1988.4. Komshian SV, Uwaydah AK, Sobel JD, Crane LR. Fungemia caused by Candida species

and Torulopsis glabrata in the hospitalized patient: frequency, characteristics, andevaluation of factors intluencing outcome. Rev Infect Dis 1989;11:379-90.

5. Gumbo T, Isada CM, Hall G, Karafa MT, Gordon SM. Candida glabrata fungemia.Medicine (Baltimore) 1999;78: 220-7.

6. Solomon SL, Khabbaz RF, Parker RH, et al. An outbreak of Candida parapsilosisbloodstream infections in patients receiving parenteral nutrition. J Infect Dis1984;149:98-1 02.

7. Solomon SL, Alexander H, Eley JW, et at. Nosocomial fungemia in neonates associatedwith intravascular pressure-monitoring devices. Pediatr Infect Dis J 1986;5:680-5.

8. Burnie JP, Odds FC, Lee W, Webster C, Williams JD. Outbreak of systemic Candidaalbicans in intensive care unit caused by cross infection. Br Med J 1985;290:746-8.

9. Phelps M, Ayliffe GAJ, Babb JR. An outbreak of candidiasis in a special care baby unit:the use of a resistogram typing method. J Hosp Infect 1986;7: 13-20.

10. Vaudry WL, Tierney AJ, Wenman WM. Investigation of a cluster of systemic Candidaalbicans infections in a neonatal intensive care unit. J Infect Dis 1988; 158: 1375-9.

11. Lee W, Burnie JP, Matthews RC, Oppenheim BO, Damani NN. Hospital outbreaks withyeasts. J Hosp Infect 1991;18:237-49.

12. Sherertz RJ, Gledhill KS, Hampton KD, et at. Outbreak of Candida bloodstreaminfections associated with retrograde medication administration in a neonatal intensivecare unit. J Pedriatr 1992; 120:455-61.

13. Sharp AM, Odds FC, Evans EGV. Candida strains from neonates in a special care babyunit. Arch Dis Childh 1992;67:48-52.

14. Romano F, Ribera G, Giuliano M. A study of a hospital cluster of systemic candidosisusing DNA typing methods. Epidemiol Infect 1994; 112:393-8.

20 Chapter 2

15. Betremieux P, Chevrier S, Quindos G, et al. Use of DNA fingerprinting and biotypingmethods to study a Candida albieans outbreak in a neonatal intensive care unit. PediatrInfect Dis J 1994;13:899-905.

16. Pertowski CA, Baron RC, Lasker BA, et at. Nosocomial outbreak of Candida albieanssternal wound infections following cardiac surgery traced to a scrub nurse. J Infect Dis1995; 172:817-22.

17. Bennett SN, McNeil MM, Bland LA, et at. Postoperative infections traced tocontamination of an intravenous anesthetic, Propofol. N Engl J Med 1995;333: 147-54.

18. Reagan DR, Pfaller MA, Hollis RJ, Wenzel RP. Evidence of nosocomial spread ofCandida albieans causing bloodstream infection in a neonatal intensive care unit. DiagnMicrobiol Infect Dis 1995;21:191-4.

19. Fotedar R, Banerjee U, Chaudhary AR. Outbreak of systemic candidiasis in low birthweight preterm infants at a neonatal intensive care unit. J Mycol Med 2000; I0: 100-4.

20. Parry MF, Grant B, Yukna M, et at. Candida osteomyelitis and diskitis after spinalsurgery: an outbreak that implicates artificial nail use. Clin Infect Dis 2000;32:352-7.

21. Weems JJ, Chamberland ME, Ward J, et at. Candida parapsilosis fungemia associatedwith parenteral nutrition and contaminated blood pressure transducers. J Clin Microbiol1987;25: 1029-32.

22. Schar G, Grehn M, von Graevenitz A. Persistent colonization of carbon dioxideincubators with Candida parapsilosis. Eur J Clin Microbiol Infect Dis 1990;9:758-60.

23. Sanchez V, Vazquez JA, Barth-Jones D, et al. Nosocomial acquisition of Candidaparapsilosis: an epidemiologic study. Am J Med 1993;94:577-82.

24. Deresinski SC, Clemons KV, Kemper CA, et at. Genotypic analysis of pseudoepidemicdue to contamination of Hanks' balanced salt solution with Candida parapsilosis. J ClinMicrobiol 1995;33:2224-6.

25. Levin AS, Costa SF, Mussi NS, et at. Candida parapsilosis fungemia associated withimplantable and semi-implantable central venous catheters and the hands of healthcareworkers. Diagn Microbiol Infect Dis 1998;30:243-9.

26. Huang YC, Lin TY, Leu HS, et at. Outbreak of Candida parapsilosis fungemia inneonatal intensive care units: clinical implications and genotyping analysis. Infection1999;27:97-102.

27. Branchini ML, pfaller MA, et al. Genotypic variation and slime production among bloodand catheter isolates ofCandida parapsilosis. J Clin Microbiol 1994;32:452-6.

28. Greaves I, Kane K, Richards NT, et at. Pigeons and peritonitis? Nephrol Dial Transplant1992;7:967-9.

29. EI-Mohandes AE, Johnson-Robbins L, Keiser JF, Simmens SJ, Aure MV. Incidence ofCandida parapsilosis colonization in an intensive care nursery population and itsassociation with invasive fungal disease. Pediatr Infect Dis J 1994;13:520-4.

30. Isenberg HD, Tucci V, Cintron F, et at. Single-source outbreak of Candida tropiealiscomplicating coronary bypass surgery. J Clin Microbiol 1989;27:2426-8.

31. Doebbeling BN, Hollis RJ, Isenberg HD, Wenzel RP, pfaller MA. Restriction fragmentanalysis of a Candida tropiealis outbreak of sternal wound infections. J Clin Microbiol1991 ;29: 1268-70.

32. Finkelstein R, Reinhertz G, Hashman N, Merzbach D. Outbreak of Candida tropiealisfungemia in a neonatal intensive care unit. Infect Control Hosp Epidemiol 1993;14:58790.

33. Sanchez V, Vazquez JA, Barth-Jones D, et at. Epidemiology of nosocomial acquisitionofCandida lusitaniae. J Clin Microbiol 1992;30:3005-8.

34. Yagupski P, Dagan R, Chipman M, et al. Pseudooutbreak of Candida guilliermondiifungemia in a neonatal intensive care unit. Pediatr Infect Dis J 1991; I0:928-32.

2. Cross-Infection with Candida in the Intensive Care Unit 21

35. Dube MP, Heseltine PNR, Rinaldi MG, Evans S, Zawacki B. Fungemia and colonizationwith nystatin-resistant Candida rugosa in a bum unit. Clin Infect Dis 1994: 18:77-82.

36. Rangel-Frausto MS, Houston AK, Bale MJ, Fu C, Wenzel RP. An experimental modelfor study of Candida survival and transmission in human volunteers. Eur J ClinMicrobiol Infect Dis 1994;13:590-5.

37. Strausbaugh LJ, Sewell DL, Ward IT, et al. High frequency of yeast carriage on handsof hospital personnel. J Clin Microbiol 1994;32:2299-2300.

38. Pittet D, Mourouga P, Perneger TV. Compliance with handwashing in a teachinghospital. Ann Intern Med 1999;130:126-30.

39. Hunter PRo A critical review of typing methods for Candida albicans and theirapplications. Crit Rev Microbiol 1991; 17:417-34.

40. Pfaller MA. Epidemiological typing methods for mycoses. Clin Infect Dis 1992;14:S4SIO.

41. pfaller MA. Epidemiology and fungal infections: the promise of molecular typing. ClinInfect Dis 1995;20: 1535-9.

42. Magee BB, Magee PT. Electrophoretic karyotypes and chromosome number in Candidaspecies. J Gen Microbiol 1987; 133:425-30.

43. Lehmann PF, Lin D, Lasker BA. Genotypic identification and characterization of speciesand strains within the genus Candida by using random amplified polymorphic DNA. JClin Microbiol 1992;30:3249-54.

44. Lockhart SR, Reed BD, Pierson CL, Soli DR. Most frequent scenario for recurrentCandida vaginitis is strain maintenance with "substrain shuffling": demonstration bysequential DNA fingerprinting with probes Ca3, CI, and CARE2. J Clin Microbiol1996;34:767-77.

45. Marco F, Lockhart SR, Pfaller MA, et al. Elucidating the origins of nosocomialinfections with Candida albicans by DNA fingerprinting with the complex probe Ca3. JClin MicrobioI1999;37:2817-28.

46. Schmid J, Voss E, Soli DR. Computer-assisted methods for assessing strain relatednessin Candida albicans by fingerprinting with the moderately repetitive sequence Ca3. JClin Microbiol 1990;28: 1236-43.

47. Fridkin SK, Jarvis WR. Epidemiology of nosocomial fungal infections. Clin MicrobiolRev 1996;9:499-511.

48. Voss A, Pfaller MA, Hollis RJ, Melchers WJG, Meis JFGM. Evaluation of thediscriminatory power of pulsed-field gel electrophoresis and PCR fingerprinting forepidemiologic typing ofCandida species. Clin Microbiol Infect 1998;4:82-7.

49. Espinel-Ingroff A, Vazquez JA, Boikov D, Pfaller MA. Evaluation ofDNA-based typingprocedures for strain categorization of Candida spp. Diagn Microbiol Infect Dis1999;33:231-9.

50. Van Belkum A, Melchers W, De Pauw BE, et al. Genotypic characterization ofsequential Candida albicans isolates from fluconazole-treated neutropenic patients. JInfect Dis 1994;169: 1062-70.

51. Barnes RA, Rogers TR, Pittet D, Burnie J, Haynes KA. Nosocomial fungal infection:diagnosis and typing. J Hosp Infect 1999;43:S215-S218.

Chapter 3

Risk Factors for Candida Infection in the IntensiveCare UnitNorth American Perspective

RHONDA V. FLEMINGl and THOMAS 1. WALSH2

Yale University School ofMedicine, New Haven, Connecticut, I and National Institutes ofHealth,Bethesda, Maryland,2 USA

Recent improvements in the delivery of health care in the fields of oncology,surgery, transplantation, and critical care have made possible the support ofcritically ill and severely immunosuppressed patients for prolonged periodsof time. As a result, the opportunity for the acquisition of nosocomialinvasive infections has increased. Data from the National NosocomialInfections Surveillance (NNIS) system revealed that the rate of fungalinfections increased from 2.0 to 3.8 per 100 hospital discharges between1980 and 1990 (1). The rate of bloodstream infection (BSI) due to Candidaspecies has increased significantly: nosocomial infections due to Candidaspecies currently rank fourth (2). The associated crude mortality is highdespite optimal treatment with amphotericin B and the new triazoles. In aprevious cohort study of nosocomial Candida fungemia, the crude andattributable mortality for cases and controls was reported to be 57% and 19%respectively. The attributable mortality rate for the infection was 38% (3).The incidence and relative prevalence of Candida infections in patientsrequiring intensive care has increased dramatically. Recent studies indicatethat 23% of Candida BSls occurred in patients hospitalized in an intensivecare unit (ICU) (4). Numerous outbreaks or clusters of infections due toCandida species in ICUs have been described (5-8) When compared topatients hospitalized in general wards, patients in the ICU are at increasedrisk for acquiring nosocomial infections including pneumonia, bloodstreamand urinary tract infections. This trend is obviously due to severalinterventions that include the high rate of invasive procedures. Suchprocedures in the ICU include insertion of central venous catheters,

24 Chapter 3

peripheral arterial access, endotracheal intubation with positive endexpiratory pressure and bladder catheterization.Risk factors identified for systemic Candida infections include the

changing demographic patterns of patients and the higher incidence ofchronic illness, debilitation, and immunosuppression. In addition, theemergence of antimicrobial-resistant pathogens as a result of the extendeduse of broad-spectrum antibiotics has created a therapeutic challenge for theclinician, due to the lack of alternative antibiotics to treat such infections.Systemic Candida infections carry a high morbidity and mortality; thereforeit is paramount for the clinician to identify those critically ill patients at highrisk for candidiasis and intervene in a timely manner to prevent suchinfections from occurring. In this review we will emphasize importantaspects of the ICU environment that contribute to the development ofnosocomial Candida infection. Preventive and therapeutic strategies will bediscussed.

RISK FACTORS FOR CANDIDIASIS IN THE INTENSIVECARE UNIT

Cross-transmission

Several factors unique to intensive care contribute to the cross-transmissionof Candida species These factors include lack of appropriate aseptictechnique and patient-to-patient transmission via the unwashed hands of ahealth care worker (HCW). Mechanisms of transmission of fungal organismsmay also involve extrinsic contamination of intravenously administeredmedications or vascular access devices. Molecular subtyping of selectedisolates incriminated contaminated syringe fluids in one outbreak ofCandidaBSI in a neonatal intensive care unit (NICU) (8). Five infants acquiredCandida fungemia as a result of contaminated retrograde medicationsyringes in association with total parenteral nutrition. Of note, the authorspostulated that the precipitating event for the outbreak could have been areduction in the frequency with which intravenous tubing was changed, fromevery 24 hours to every 72 hours, in accordance with hospital policy.Health care workers play an important role in the transmission of

Candida infections. Yeasts are frequently isolated from the hands of HCWsand can be transmitted from hands to patients (7,9). The first description ofcross-infection between HCWs and patients with systemic candidiasis wasreported by Burnie et al. in 1985 (10). Among patients hospitalized in anICU, 14 were identified with systemic candidiasis and 25 with superficialinfection. The strain that caused the outbreak was responsible for all the

3. Risk Factors for Candida Infection in the Intensive Care Unit 25

cases of candidiasis in the ICU. The same strain was also isolated from oralswabs of four ICU nurses and from the hands of one of these nurses. Noenvironmental source was identified in this outbreak. Yeast colonizationplays an important role in the epidemiology of transmission of Candidaspecies in ICUs. A recent study demonstrated that as many as 75% ofpatients in ICUs are colonized with Candida species, mostly C. albicans(11). Likewise, 67% of HCWs in ICUs harbored Candida species in theiroropharynx or on their hands. Interaction between HCWs and patientscolonized with same Candida strains provided evidence for crosstransmission.Nursing techniques are also potentially associated with line

contamination and cross-infection (8). A survey of 43 NICU nursessuggested that around 50% of them reused syringes for line flushing. Onsome occasions, staff members reported that syringes containing 10%glucose were moved from the old line to the new line at the time ofintravenous tubing change.Non-perinatal nosocomial transmission of Candida species among

neonates is frequently seen in NICUs, probably as a result of contaminationof the hands of HCWs or the parents. Vertical transmission of Candidaspecies from the mother to the infant is seen less frequently. However, anendogenous source of candidemia was suggested during one outbreak in aNICU (12). Epidemiologic aspects of candidemia in NICUs will bediscussed elsewhere in this chapter.

Host-specific factors

Critically-ill patients hospitalized in an ICU are particularly susceptible tonosocomial infections and the ability to overcome such complications isseverely impaired due to breakdown of normal host defenses. The normalskin and mucosal barriers are frequently compromised by the use of invasivedevices. In addition, these patients often have severe underlying illness,immunosuppression, malnutrition, and a history of multiple hospitalizationsthat predispose them to a variety of infectious complications. Other hostrelated factors that need to be considered are extremes of age, malignancies,autoimmune disorders, splenectomy, diabetes mellitus, renal insufficiencyand other infections that can impair the host's immune response.Frequently, critically-ill patients have multiple breaches of normal skin

and mucosa, partly because of iatrogenic factors related to the highfrequency of invasive procedures required for monitoring and treatment.Endotracheal intubation bypasses the patient's respiratory mucosal clearancemechanism, and predisposes them to lower respiratory tract infections.Bums, decubitus ulcers and surgical debridement result in loss of the

26 Chapter 3

protective effect of the integument. Percutaneous devices, such asintravascular catheters, surgical drains, bladder catheters and intracranialpressure monitors, provide an important portal for microorganisms to enterthe bloodstream.Nutrition is often compromised in critically-ill patients. Malnutrition

contributes to altered immune function, delayed wound healing, andincreased risk of infections. Nutritional supplementation also carries the riskof complications. Enteral nutrition may be associated with increased risk ofaspiration, whereas intravenous hyperalimentation requires the use ofintravascular catheters with the inherent risk of fungemia.

Environmental factors

The ICU represents a mixed and unique ecosystem of microorganisms,patients, HCWs, and inanimate objects. Hospital staff and environmentalsurfaces may serve as a reservoir for infections. The open nature of manyICUs allows for an increased interaction between the staff and medicalinstruments that may be harboring the pathogenic microorganism, thusfacilitating the spread of nosocomial pathogens. Environmental factorspresent in the ICU setting, that can potentially be contaminated or transmitthe infection, include irrigation solutions, ventilators, sinks, potable water,humidifiers, drugs, and syringes.Several environmental factors were evaluated during an outbreak of

candidiasis in a NICU (8). Topical solutions, including baby soap, handlotion, ointment, hand-washing agent, adhesive remover and othermiscellaneous agents, proved culture-negative for Candida species However,fluids from syringes used for retrograde medication administration weremore likely to grow these organisms (11 of 267, 4.1%) than any other fluidssampled (one of 339, 0.1%). In another outbreak in a NICU, an associationwas demonstrated between C. parapsilosis fungemia and receipt of glycerinsuppositories among four neonates (13). It was postulated that thecontaminated bottle containing the glycerin was the vector for the infection.In contrast, in other ICU outbreaks, environmental specimens were allculture-negative for Candida species, indicating that the contaminated handsof HCWs were the common source for the transmission of the infection(6,9,10,14).


SITE-SPECIFIC INFECTIONS

Pneumonia

Pneumonia is the most commonly reported nosocomial infection incritically-ill patients and is usually associated with mechanical ventilation.The incidence of nosocomial pneumonia in mechanically ventilated patientsranges from 10 to 65% (15,16). Given the lack of specificity of clinical signsin nosocomial pneumonia, the diagnosis of pneumonia in the ICU settingrepresents a clinical challenge to the physician. Fever and leukocytosis arenot specific for pneumonia; in addition, infiltrates on chest radiographs maybe due to non-infectious complications commonly seen in critically-illpatients. Fungal pneumonia due to Candida species is more commonly seenin immunosuppressed patients with cancer (17). The recovery of Candidaspecies from respiratory secretion specimens suggests airway colonizationrather than infection (18); therefore, the only acceptable proof of Candidapneumonia is histologic demonstration of the fungi in lung tissue (17). Therole of Candida species in the pathogenesis of nosocomial pneumonia inICUs has not been established and, to date, there have been no reports ofclusters or outbreaks of pneumonia due to Candida species.

Bloodstream infections

Candida species are important causes of bloodstream infections in the ICU.They rank fourth in the list of causes of nosocomial BSI (1), and account for23% of all bloodstream isolates in critically-ill patients (4). Recently, therehas been an increase in the number of clusters and outbreaks of BSI due toCandida species in high-risk settings, such as the NICU and the surgicalintensive care unit (SICU) (5,6,8-10,13,14,19). The high rate of fungemia inthis population is associated with several factors. Cross-infection frompatient to patient occurs in high proportion via the unwashed hands ofHCWs (20). Endogenous infection after previous colonization of thegastrointestinal tract has also been demonstrated (21). Invasive diagnosticand therapeutic interventions, such as percutaneous intravenous lines, drainsand intracranial pressure monitors, frequently breach the protective layer ofthe dermis and serve as a conduit for pathogenic organisms to enter thebloodstream.

Candida albicans remains the most common cause of nosocomialCandida bloodstream infections in ICUs. In a recent survey of Candida BSIin NICUs and SICUs, C. albicans was the species most commonly isolated(63% and 48%, respectively), followed by C. glabrata (6% and 24%), and C.parapsilosis (29% and 7%) (22). Overall, the reported rate ofCandida BSI in

28 Chapter 3

SICUs was 9.82 per 1,000 admissions (0.99 per 1,000 patient-days). InNICUs the rate was 12.29 per 1,000 admissions (0.64 per 1,000 patientdays). Candida species have also been implicated as causes of primary BSIin medical ICUs (23). Eleven percent of BSls were fungal in nature, andmore than half of these were caused by C. albicans. In this study, noassociation could be detected between Candida BSI and central venouscatheters.Other factors linked to the increased rate of Candida BSI in the ICU are

associated with the use of broad-spectrum antibiotics (24,25). The empirictreatment of critically ill patients with sepsis is generally begun before theresults of cultures are known. The antibiotics available for broad-spectrumcoverage include vancomycin, third generation cephalosporins,aminoglycosides, and quinolones. The increased use of cephalosporins inICUs has led to increased isolation rates of Candida species, as reportedrecently (26). Changes in the gut microflora associated with broad-spectrumantibiotics may play a role in bacterial translocation and overgrowth ofCandida species in the intestinal lumen with subsequent vascular invasion.

Urinary tract infections

Urinary tract infections (UTIs) constitute the second most common group ofnosocomial infections in the ICU. The urinary tract accounts for around 40%of all nosocomial infections, the major predisposing factor being thepresence of a urinary catheter. The diagnosis of fungal UTI, however,presents a challenge to the clinician. The presence of Candida in the urinemay be indicative of true infection, or merely be representative ofcolonization. The lack of specific signs and symptoms of infection makes thediagnosis of fungal UTI even more complex, because patients with CandidaUTI may be asymptomatic (23). In the absence of an underlying chronicmedical condition, the detection of Candida species in the urine mayrepresent colonization or low-grade infection that often resolves withremoval of the urinary catheter (27).

In one study of patients with persistent candiduria, fungal UTI wasclassified as complex (upper tract or disseminated) or simple (confined to thebladder) (28). Risk factors identified for complex infection includedobstructive uropathy, malnutrition, neoplasia, renal failure, and prolongedantibiotic use. Likewise, in a recent multicenter prospective surveillancestudy of patients with funguria, diabetes mellitus (39%), urinary tractabnormalities (37.7%) and malignancies (22.2%) were risk factorsassociated with funguria (27). In this study, C. albicans accounted for morethan half of the fungal isolates, followed by C. glabrata in 15.6% of cases.


Fungal UTI is also common in the pediatric population. In a retrospectivestudy of 54 pediatric patients with persistent candiduria, disseminatedCandida infection was detected in 11% ofcases. Invasive infection was mostcommonly seen in neonates, and patients with central venous cathetersand/or receiving immunosuppressive therapy. Similarly, in a retrospectivestudy of infants admitted to a NICU, Candida species were implicated in42% of UTIs. In this population, Candida fungemia was detected in 87% ofinfants. Ascending infection is an important complication of Candidafunguria in neonates. In a study of 41 neonates with funguria in a NICU,42% had evidence of renal candidiasis (renal fungus ball or renal fungalabscess) by renal sonogram (29). Complications requiring surgicalintervention were uncommon in this group.In one study of nosocomial infections in critical care patients, C. albicans

accounted for approximately half of the fungal isolates from urine (23). Inthe same study, the development of Candida funguria was highly associatedwith the use of urinary catheters. Although several reports have identified C.albicans as the commonest fungal pathogen in UTIs, C. glabrata is alsoassociated with funguria. Risk factors for both C. albicans and C. glabratainfection are female gender, and being in the ICU. In contrast, C. glabratafunguria has specifically been associated with the use of fluconazole, as wellas with quinolone use (30).Management of ICU patients with candiduria depends on whether or not

they have signs of invasion or dissemination. If such signs are present,systemic antifungal therapy is required. On the other hand, patients withbladder infection alone present a therapeutic dilemma. These patients shouldbe given antifungal therapy if urine cultures contain more than 10,000colony forming units per ml (31). The bladder infection can be treated withirrigations of amphotericin B or with oral fluconazole. In a recent placebocontrolled trial, the eradication rate ofCandida funguria in patients receivingoral fluconazole (200 mg per day for 14 days) was 50% (32). However,long-term eradication was not associated with clinical benefit. The use ofamphotericin B bladder irrigations has proved to be a safe and effectivetherapy for candiduria, however, the dosage and duration of treatmentremain controversial (33). The persistence of candiduria following oralfluconazole or local amphotericin B treatment suggests a resistant fungalstrain or invasive and complex infection (34).

ANTIMICROBIAL USE IN THE INTENSIVE CARE UNIT

The use of broad-spectrum antibiotics in the care of critically-ill patients hasbeen extensively abused in intensive care units (35). Over 75% of patients

30 Chapter 3

admitted to an ICU receive broad-spectrum antibiotics at some point duringtheir stay, regardless of whether or not there is clear justification ordocumented infection. No other factor is more important for thedevelopment of antimicrobial drug resistance. Recent data from the NNISsystem for the period from 1990 to 1995 demonstrated a dramatic increase inantimicrobial resistance among nosocomial pathogens in ICUs (36). Morerecently, there have been reports of resistance to antifungal therapy, and ithas been postulated that the increased use of fluconazole in the ICU settingmay lead to the emergence of drug-resistant fungal strains (37-39).According to one recent study, the use of fluconazole in critically-ill patientshas been associated with increased numbers of resistant bacterial strains,with longer lengths of stay in ICU, and with increased mortality (40).Antibiotic restriction programs should be implemented to limit the

emergence of resistant pathogens. Measures should include the restriction ofcertain broad-spectrum antibiotics to situations approved by experts in thefield, automatic antibiotic stop orders, restricted reporting of drugsusceptibilities and educational materials for medical staff. When antibioticsare prescribed, only the narrower regimens should be authorized.Appropriate infection work up should be undertaken at the time empiricantimicrobial treatment is started, to permit judicious selection of the mosteffective drugs once the laboratory results become available.

CANDIDA SPECIES OF EPIDEMIOLOGICSIGNIFICANCE

Intensive care units, in general, are associated with numerous risk factorsand with an increased incidence of nosocomial fungal infections. C. albicansconstitutes, by far, the most commonly isolated fungal pathogen in the ICUsetting. Reports from the NNIS system between 1990 and 1995 ranked C.albicans as the second most frequent organism from urinary catheterassociated UTIs. In addition, C. albicans was implicated in 5.9% of allvascular catheter-associated BSls in ICUs. However, there are severalfactors, associated with the ICU ecosystem, that may influence thetransmission of other Candida species, at times in epidemic proportions.In neonatal ICUs, a recent case-control study reported an increased rate

of infections with non-albicans species of Candida among neonates withfungemia (41). C. parapsilosis and C. tropicalis were found in 26.5% and20.4% of the cases, respectively. Mechanical ventilation and antibacterialagents were postulated as risk factors for infection. In another study, C.parapsilosis and C. tropicalis (25% and 13%, respectively) were the most


frequent non-albicans species isolated from neonates with UTI in a NICU(42).Other non-albicans species of Candida have been involved in several

clusters of infections in ICUs. The recent National Epidemiology ofMycoses Survey (NEMIS) documented the etiology of invasive fungalinfections among patients admitted to NICUs and SICUs (43). Species otherthan C. albicans were involved in nine of 13 clusters. Instances of potentialtransmission from patient to patient involved C. albicans, C. glabrata, C.parapsilosis, and C. tropicalis; and from HCW to patient involved C.albicans, C. parapsilosis and C. krusei. No differences in mode oftransmission were observed between NICUs and SICUs. In addition to whatseems to be an increase in the rate of nosocomial fungal infections, there area growing number of reports of outbreaks of Candida fungemia in NICUs.A recent review of NNIS system data for 181,993 patients in medical

ICUs in the United States revealed that C. albicans and C. glabrataaccounted for 6% and 2%, respectively of BSI (23). Fungal UTls were morefrequent: C. albicans accounted for 21% of all cases with UTI, while nonalbicans species constituted 10% of all cases (23). Of particular concern isthe indiscriminate use of fluconazole in medical ICUs because this may leadto the emergence of resistance. In a retrospective comparative study ofpatients admitted to medical and surgical ICUs, emergence of non-albicansspecies of Candida tolerant to fluconazole was observed in individualstreated with this agent (40). The same study also reported an increased rateof antibiotic-resistant bacterial strains following fluconazole administration.

SPECIFIC INFECTION PROBLEMS IN THE INTENSIVECARE UNIT

Pressure transducers

Pressure-monitoring devices (transducers) are regularly used in critically illpatients for hemodynamic monitoring. However, they can provide a portal ofentry for systemic infections. The intravascular pressure-monitoring devicesthat are used in conjunction with arterial catheters, have been implicated inseveral outbreaks of nosocomial bacterial and fungal BSI. The first outbreakof Candida infection, due to contamination of pressure-monitoring devices,occurred in 1982 (44). Eight neonates developed BSI due to C. parapsilosisafter having received total parenteral nutrition through an umbilical arterycatheter, which had also been used to monitor arterial pressure. Thetransducer domes were culture-positive for C. parapsilosis. Contaminatedblood pressure transducers were also implicated in an outbreak of C.

32 Chapter 3

parapsilosis BSI that involved 12 pediatric patients (45). The use of centralvenous nutrition therapy and longer duration of exposure to blood pressuretransducers were identified as risk factors for infection. The authors alsoreported the isolation of C. parapsilosis from 32% of pressure transducers.There have been no reports of other Candida species being involved in BSIassociated with pressure-monitoring devices.Bloodstream infections, associated with pressure transducers, have been

attributed to a lack of proper disinfection of reusable devices, particularly thechamber domes which can serve as a reservoir for the organism (46).Because of difficulties in sterilizing reusable transducers, sterile plasticchamber domes were developed. However, several outbreaks of bacterialinfection were reported despite the use of sterile domes. These infectionswere attributed to the touch contamination of the pressure-monitoring systemduring assembly. Other mechanisms by which pressure-monitoring systemshave been contaminated include contamination of infusate, as evidenced byinfusion systems containing parenteral nutrition fluid (44). The introductionof pressure-monitoring systems with continuous flush devices or disposabletransducers has minimized the risk of contamination and infection. Nooutbreaks have been reported since the introduction of these disposablesystems.

Circulatory assist devices

Mechanical cardiac assistance has recently emerged as an option for patientswith end-stage heart failure. Several types of left ventricular circulatoryassist device (LVAD) are currently available for circulation support whilepatients are awaiting cardiac transplant. Infection during the post-operativeperiod remains as the most serious complication. Fungal infectionsassociated with LVADs have included device-related BSIs and, lesscommonly, endocarditis. Reports of fungal BSI following LVADimplantation include a case of C. tropicalis fungemia (47), and three cases ofCandida species infection (48). More recently, Nurozier et ai. documented ahigh rate (22%) of fungal infection among 37 patients after LVADimplantation (49). Five of these patients met the diagnostic criteria forCandida endocarditis. Successful management of fungal LVAD infectionsrequires the early recognition ofpotential infection, and prompt institution ofantifungal therapy. In cases where fungal endocarditis is documented, deviceremoval or replacement is required.


Neurosurgical devices

Indwelling cerebral-monitoring devices (ICMDs) are commonly used in theneurosurgical ICU for the measurement and treatment of intracranialpressure, temperature and chemical environment. These devices have beenassociated with a number of infectious complications (50). Likewise, theepidural catheters that are frequently used for pain management oranesthesia also have the potential to cause device-related infections.Although epidural catheters are usually left in place for less than 48 hours,their prolonged use may sometimes be required. These catheters arecommonly colonized with gram-positive bacteria and subsequent infectionsare often superficial. Deeper infection of the central nervous system, such asepidural abscess, is less common (51), but meningitis is now being seenmore frequently, associated with the use of cerebrospinal fluid (CSF) shunts.In one recent report, a case of C. tropicalis vertebral osteomyelitis followedepidural catheterization (52). In addition, Candida species have beenimplicated in several cases of meningitis that followed shunt infections (5357). The overall mortality of Candida meningitis ranges from nine to 25%;treatment consists of the early initiation of systemic amphotericin B therapy,accompanied by the removal of the shunt in most cases. In somecircumstances, the clinical significance of Candida isolates from the CSF ofpatient with shunts is difficult to assess. A retrospective study of patients inwhom Candida species were isolated from the CSF following neurosurgery,indicated that the diagnosis of Candida meningitis could only be reliablyestablished by repeated positive cultures of samples obtained from both theindwelling device and by lumbar puncture (58).Intracranial pressure-monitoring devices are also associated with a

substantial risk of infection (59-62). The major risk factors associated withinfection appear to be the duration of device use greater than 5 days, and thedevice type. Infections associated with these devices are mainly bacterial; todate, there have been no reports of fungal infections.

Anesthetic agents

In 1990, the Centers for Diseases Control and Prevention (CDC) receivedreports of five outbreaks of postoperative Candida bloodstream infectionsthat were traced to extrinsic contamination of an intravenous lipid-basedanesthetic agent, propofol (Diprivan) (63). In one of the clusters, four nonimmunocompromised patients developed endogenous Candidaendophthalmitis after they had undergone non-ophthalmologic surgery (64).Propofol presents a particular infection risk because it is lipid-based,contains no preservatives, is stored at room temperature, and is supplied in

34 Chapter 3

vials that may be used on multiple occasions. Propofol is more likely thanany other parenteral fluid to support bacterial growth when contaminated,and more frequent replacement of intravenous tubing may be required whenit is administered.

CANDIDEMIA IN NEONATAL INTENSIVE CARE UNITS

Nosocomial infections result in considerable morbidity and mortality amongneonates, especially those in intensive care. The number of reportedoutbreaks of nosocomial Candida infections in NICUs has been increasing(6-9,13,14,65-68), as has the overall rate of invasive candidiasis in theseunits. Over the 15-year period from 1981 to 1995, the number of cases ofCandida BSI seen in NICUs increased more than II-fold, from 2.5 per 1000to 28.5 per 1000 admissions. Traditionally, it has been thought that theacquisition of C. albicans by neonates occurs via mother-to-infanttransmission (69), or from the endogenous flora of colonized patients.However, recent epidemiologic studies, supported by molecular typing, havedemonstrated that exogenous infection, due to the administration ofcontaminated fluids (70), cross-infection (13), and colonized hands ofHCWs(14), is also important for the transmission of Candida species amongneonates in NICUs. Non-perinatal transmission of Candida speciescommonly occurs by transmission in NICUs via cross-contamination or bycommon contaminated sources (8,10).Among the risk factors for fungal BSI that have been identified in

neonates are: prematurity (especially very-low-birth-weight neonates), use ofbroad-spectrum antibiotics, prolonged mechanical ventilation, coagulopathy,parenteral nutrition, catheterization of central vessels, H2 blocker therapy,and prolonged hospitalization in a NICU (71). A recent case-control studycharacterized the clinical manifestations of Candida BSI among 49 neonatesin NICUs (41). The most common finding was abdominal distention(48.8%), followed by poor peripheral perfusion (45.6%) and fever (42.8%).In the CSF, protein concentrations and neutrophil counts tended to be higherthan in non-infected neonates. None of the cases had evidence of Candidaendophthalmitis. However, evidence of fungal dissemination wasdemonstrated in the kidneys (7.1%), liver (2.5%) and heart (6.6%). C.albicans was the leading cause of infection, being isolated in 42.8% of thecases, followed by C. parapsilosis and C. tropicalis in 26.5% and 20.4% ofthe cases, respectively.Among the Candida species pathogenic to humans, C. albicans remains

the species most frequently associated with BSI in the NICU. However,recent trends towards an increase in non-albicans species of Candida have


been reported (13,22,41). At least four reported outbreaks ofCandida BSI inNICUs have involved non-albicans species (Table 1). More recently, variousreports have suggested that an increasing number of infections attributable toC. parapsilosis are occurring in NICUs. In general, clinical reports suggestthat C. parapsilosis is a less virulent organism than C. albicans. However,two recent comparisons of neonatal BSI due to C. albicans and C.parapsilosis demonstrated no significant differences in the fungaleradication rate or the overall mortality rate (72,73).

Table 1. Outbreaks or clusters of Candida infections in neonatal ICUs

Year

198419861987-91198819901991199119941995ND

Species NC.albicans 4C. albicans 7C. parapsilosis 58C. tropicalis 6C. albicans 5C. parapsilosis 5C. albicans 7C. parapsilosis 17C. albicans 9C. albicans 4

3

Source

UnknownUnknown

Hand-borne •Hand-borne bRetrograde syringesGlycerin bottleHand-borneHand-borneHand-borneCross-transmission

Duration

2m7m55 m4m35 d7d15 d5m4m10m20 d

Ref.

7666868136714965

N, number; ND, not documented;" 4 nurses and colonized patients were considered reservoirs of C. parapsilosis; b, included anurse and housekeeper with onychomycosis

The increased morbidity of Candida BSI in neonates admitted to theNICU mandates a high index of suspicion of this infectious complication andinstitution of early treatment with amphotericin B. New and more effectivestrategies must be developed for prevention of transmission in the intensivecare setting.

TREATMENT OF INVASIVE CANDIDIASIS

Fungal infections, particularly invasive candidiasis, are among the mostserious infections acquired by critically ill patients requiring intensive care.The coexistence of other morbid conditions and the increased severity ofillness for patients hospitalized in ICUs, mandates a high index of suspicionand early initiation of antifungal therapy for improved patient outcome. Asdescribed earlier, Candida species cause a broad range of invasive infectionsthat require different therapeutic strategies. In addition, the choice of therapywill be determined by weighing the greater activity of amphotericin B forazole-resistant Candida species against the lesser toxicity of the azole

36 Chapter 3

antifungal agents. Treatment of invasive candidiasis due to non-albicansspecies of Candida may be guided by in-vitro susceptibility testing,particularly in those patients previously treated with azoles in whomacquired antifungal drug resistance should be considered.

An extensive discussion of the treatment of invasive candidiasis isbeyond the scope of this chapter. Herein we will summarize currenttherapeutic approaches to invasive candidiasis as recommended in the latestInfectious Diseases Society ofAmerica guidelines (74). We will describe thetreatment ofCandida infections in non-neutropenic patients.Among the currently available antifungals for the treatment of fungal

infections, amphotericin B remains the standard agent for the treatment ofCandida infections. The newer lipid formulations of this drug havesubstantial advantages over conventional amphotericin B deoxycholate inthat they are less nephrotoxic and appear to be at least as active as the parentcompound. Three lipid formulations of amphotericin B have been approvedfor use in humans: amphotericin B lipid complex (ABLC, Abelcet),amphotericin B colloidal dispersion (ABCD, Amphotec or Amphocil), andliposomal ampotericin B (LAB, AmBisome). Only ABLC and LAB havebeen approved for use in proven candidiasis in patients intolerant of, orrefractory to, conventional amphotericin B. The optimal dose of theseformulations for severe Candida infections is unclear; however, dosages of3-5 mglkg per day appear to be suitable for treatment of serious infections.Treatment of hematogenous candidiasis should include removal of all

existing central venous catheters whenever feasible, and particularly forinfections due to C. parapsilosis. Amphotericin B (0.5-0.6 mgikg per day)and fluconazole (400 mg per day) have been shown to have similar efficacyin treating hematogenous candidiasis (75). Choice of therapy will depend onpatient status and antifungal susceptibility patterns of the infecting isolate. Instable patients who have not received previous therapy with an azole,treatment with fluconazole at a dose of >6 mgikg per day seems to beappropriate (76). However, in clinically unstable patients infected with anunknown Candida species, conventional amphotericin B at ?0.7 mgikg perday, or a lipid formulation of amphotericin B, would be the drug of choicedue to its broader spectrum (76). Neonates with disseminated candidiasis areusually treated with amphotericin B because of its low toxicity. Infectionscaused by C. albicans, C. tropicalis and C. parapsilosis may be treated witheither amphotericin B (0.6 mglkg per day) or fluconazole (6 mgikg per day).C. glabrata infections are usually treated with amphotericin B (?0.7 mglkgper day) as initial therapy. If the infecting isolate is identified as C. krusei,conventional amphotericin B (1.0 mgikg per day) or a lipid formulation ofamphotericin B is the treatment of choice. For infections due to C.lusitaniae, fluconazole (6 mglkg per day) is the preferred therapy given the


resistance of some isolates of this organism to amphotericin B. Treatment ofcandidemia should be continued for 2 weeks after the last positive bloodculture and clinical resolution of infection.

PREVENTION STRATEGIES

Hand washing

The hands of medical staff constitute the major source of infectingorganisms that are carried from patient to patient or from caregiver topatient. Hand washing is therefore considered to be the single mostimportant measure to prevent the transmission of infection in hospitals.There is evidence that good hand washing practices are associated with alow nosocomial infection rate in the ICU (77). Washing should beencouraged between patient contacts, after contact with potentially infectiousmaterials, and after removal of examination gloves. The CDC recommendshand washing with bland soap. Plain soap and water alone fail to eradicatemicroorganisms present on the hands when contamination is heavy. Handantisepsis by surgical scrub or alcohol-based handrub is recommendedbefore the insertion of invasive devices, when persistent antimicrobialactivity and reduction in skin flora is desired (78). To improve the handwashing compliance of HCWs, new interventions have been developed suchas use of automated sinks, new emollient soaps, handrub solutions andclorhexidine-containing soaps (79). Hand washing sinks should be readilyavailable, preferably at the entrance to the patient rooms. Hands-off sinkswith foot or knee controls may limit the risk of hand contamination.

Gloves

Glove use is not intended to replace hand washing. Rather, gloves should beused in addition to hand washing, to provide an additional physical barrier tocross-transmission. When used properly, gloves protect the HCW frombacteria, viruses and fungi and also prevent the transmission of thesepathogens to the patient. Glove changes must be performed before and afterany contact with patients or with any infectious materials. Glove use may noteliminate the possibility of hand contamination, and failure to change glovesappropriately has resulted in spread of infections in the ICU (80).

38

Prevention of catheter-related infections

Chapter 3

Strict hand washing and aseptic technique constitute the basis of preventionof catheter-related infections. Additional measures, however, are necessaryand must be considered when formulating preventive strategies. Suchmeasures include selection of the appropriate type of catheter for the site ofinsertion, the administration of intravenous fluids at appropriate intervals,good adherence to techniques of catheter-site care, use of filters, flushsolutions, prophylactic antimicrobials and newer intravascular devices.Catheter materials play an important role in the pathogenesis of catheter

related BSI. Silicone catheters are associated with lower rate of infectionthan polyvinyl chloride: 0.83 and 19 per 1,000 catheter days, respectively.However, silicone catheters are tunneled and definite conclusions aboutcatheter materials cannot be established. Good barrier precautions during theinsertion of a central venous catheter should provide adequate protectionagainst infection, and the risk of subsequent catheter contamination andcatheter-related BSI should be minimized, regardless ofwhether the catheterwas inserted in the operating room or at the bedside (81). The longer theduration of catheterization, the greater the risk of infection. Routinereplacement of central venous catheters at specified intervals has beenadvised as a strategy to reduce infection (82). Catheter replacement over aguidewire is accepted as a means of replacing a malfunctioning catheter, orexchanging a pulmonary arterial catheter for a central venous catheter wheninvasive monitoring is no longer required (83). However, a higher rate ofnosocomial BSI was associated with catheters replaced over a guidewire,compared with those inserted percutaneously (84). Several studies suggestthat if a guidewire-assisted catheter replacement is conducted in a setting ofinfection, the catheter should then be removed (85,86). Catheter-site care isan important component of the care of central venous catheters. Skincleansing/antisepsis at the insertion site is considered to be one of the mostimportant measures to prevent catheter-related BSI. Several localdisinfectants and antiseptics are available for insertion-site care, such aschlorhexidine, 10% povidone-iodine, and tincture of iodine, but theirefficacy in preventing BSI needs to be determined. The application ofantimicrobial ointments to the catheter site may significantly increase therate of colonization of the catheter by Candida species (87,88).

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40 Chapter 3

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29. Bryant K, Maxfield C, Rabalais G. Renal candidiasis in neonates with candiduria.Pediatr Infect Dis J 1999; 18:959-63.

30. Harris AD, Castro J, Sheppard DC, Carmeli Y, Samore MH. Risk factors for nosocomialcandiduria due to Candida glabrata and Candida albicans. Clin Infect Dis 1999;29:9268.

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32. Sobel JD, Kauffman CA, McKinsey D, et al. Candiduria: a randomized, double-blindstudy of treatment with fluconazole and placebo. The National Institute of Allergy andInfectious Diseases (NIAID) Mycoses Study Group. Clin Infect Dis 2000;30: 19-24.

33. Occhipinti DJ, Schoonover LL, Danziger LH. Bladder irrigation with amphotericin B fortreatment of patients with candiduria. Clin Infect Dis 1993;17:812-3.

34. Ang BS, Telenti A, King B, Steckelberg JM, Wilson WR. Candidemia from a urinarytract source: microbiological aspects and clinical significance. Clin Infect Dis1993; 17:662-6.

35. Monnet DL, Archibald LK, Phillips L, et al. Antimicrobial use and resistance in eightUS hospitals: complexities of analysis and modeling. Intensive Care AntimicrobialResistance Epidemiology Project and National Nosocomial Infections SurveillanceSystem Hospitals. Infect Control Hosp Epidemiol 1998; I9:388-94.

36. Archibald L, Phillips L, Monnet D, et al. Antimicrobial resistance in isolates frominpatients and outpatients in the United States: increasing importance of the intensivecare unit. Clin Infect Dis 1997;24:211-5.

37. Sandven P. Detection of fluconazole-resistant Candida strains by a disc diffusionscreening test. J Clin Microbiol 1999;37:3856-9.

38. Vanden Bossche H, Dromer F, Improvisi I, et al. Antifungal drug resistance inpathogenic fungi. Med Mycol I998;36(Suppl 1):119-28.


39. Pfaller MA, Lockhart SR, Pujol C, et al. Hospital specificity, region specificity, andfluconazole resistance of Candida albicans bloodstream isolates. J Clin Microbiol1998;36: 1518-29.

40. Rocco TR, Reinert SE, Simms HH. Effects of fluconazole administration in critically illpatients: analysis of bacterial and fungal resistance. Arch Surg 2000; 135: 160-5.

41. Makhoul IR, Kassis I, Smolkin T, Tamir A, Sujov P. Review of 49 neonates withacquired fungal sepsis: further characterization. Pediatrics 200 I; I07:61-6.

42. Phillips JR, Karlowicz MG. Prevalence of Candida species in hospital-acquired urinarytract infections in a neonatal intensive care unit. Pediatr Infect Dis J 1997; 16: 190-4.

43. Pfaller MA, Messer SA, Houston A, et al. National epidemiology of mycoses survey: amulticenter study of strain variation and antifungal susceptibility among isolates ofCandida species. Diagn Microbiol Infect Dis 1998;31 :289-96.

44. Solomon SL, Alexander H, Eley JW, et al. Nosocomial fungemia in neonates associatedwith intravascular pressure-monitoring devices. Pediatr Infect Dis 1986;5:680-5.

45. Weems 11, Chamberland ME, Ward J, et al. Candida parapsilosis fungemia associatedwith parenteral nutrition and contaminated blood pressure transducers. J Clin Microbiol1987;25: 1029-32.

46. Beck-Sague CM, Jarvis WR. Epidemic bloodstream infections associated with pressuretransducers: a persistent problem. Infect Control Hosp Epidemiol 1989; I0:54-9.

47. Fischer SA, Trenholme GM, Costanzo MR, Piccione W. Infectious complications in leftventricular assist device recipients. Clin Infect Dis 1997;24: 18-23.

48. McCarthy PM, Schmitt SK, Vargo RL, et al. Implantable LVAD infections: implicationsfor permanent use of the device. Ann Thorac Surg 1996;61 :359-65.

49. Nurozler F, Argenziano M, Oz MC, Naka Y. Fungal left ventricular assist deviceendocarditis. Ann Thorac Surg 200 1;71 :614-8.

50. Guyot LL, Dowling C, Diaz FG, Michael DB. Cerebral monitoring devices: analysis ofcomplications. Acta Neurochir (Wien) 1998;71 (Suppl):47-9.

51. Strafford MA, Wilder RT, Berde CB. The risk of infection from epidural analgesia inchildren: a review of 1620 cases. Anesth Analg 1995;80:234-8.

52. Eisen DP, MacGinley R, Christensson B, Larsson L, Woods ML. Candida tropicalisvertebral osteomyelitis complicating epidural catheterisation with disease paralleled byelevated D-arabinitoIlL-arabinitol ratios. Eur J Clin Microbiol Infect Dis 2000; 19:61-3.

53. Murphy K, Bradley J, James HE. The treatment of Candida albicans shunt infections.Childs Nerv Syst 2000; 16:4-7.

54. Montero A, Romero J, Vargas JA, et al. Candida infection of cerebrospinal fluid shuntdevices: report of two cases and review of the literature. Acta Neurochir 2000; 142:67-74.

55. Sanchez-Portocarrero J, Martin-Rabadan P, Saldana CJ, Perez-Cecilia E. Candidacerebrospinal fluid shunt infection. Report of two new cases and review of the literature.Diagn Microbiol Infect Dis 1994;20:33-40.

56. Sugarman B, Massanari RM. Candida meningitis in patients with CSF shunts. ArchNeurol 1980;37: 180-1.

57. Gower DJ, Crone K, Alexander E, Kelly DL. Candida albicans shunt infection: report oftwo cases. Neurosurgery 1986; 19: 111-3.

58. Geers TA, Gordon SM. Clinical significance of Candida species isolated fromcerebrospinal fluid following neurosurgery. Clin Infect Dis 1999;28: 1139-47.

59. Hickman KM, Mayer BL, Muwaswes M. Intracranial pressure monitoring: review of riskfactors associated with infection. Heart Lung 1990;19:84-90.

60. Bader MK, Littlejohns L, Palmer S. Ventriculostomy and intracranial pressuremonitoring: in search of a 0% infection rate. Heart Lung 1995;24: 166-72.

42 Chapter 3

61. Rebuck JA, Murry KR, Rhoney DH, Michael DB, Coplin WM. Infection related tointracranial pressure monitors in adults: analysis of risk factors and antibioticprophylaxis. J Neurol Neurosurg Psychiatry 2000;69:381-4.

62. Aucoin PJ, Kotilainen HR, Gantz NM, et al; Intracranial pressure monitors.Epidemiologic study ofrisk factors and infections. Am J Med 1986;80:369-76.

63. Bennett SN, McNeil MM, Bland LA, et at. Postoperative infections traced tocontamination of an intravenous anesthetic, propofol. N Engl J Med 1995;333:147-54.

64. Daily MJ, Dickey JB, Packo KH. Endogenous Candida endophthalmitis after intravenousanesthesia with propofol. Arch Ophthalmol 1991; I09: 1081-4.

65. Rodero L, Hochenfellner F, Demkura H, et at. [Nosocomial transmission of Candidaalbicans in newborn infants]. Rev Argent MicrobioI2000;32: 179-84.

66. Vaudry WL, Tierney AJ, Wenman WM. Investigation of a cluster of systemic Candidaalbicans infections in a neonatal intensive care unit. J Infect Dis 1988;158:1375-9.

67. Betremieux P, Chevrier S, Quindos G, et al. Use of DNA fingerprinting and biotypingmethods to study a Candida albicans outbreak in a neonatal intensive care unit. PediatrInfect Dis J 1994;13:899-905.

68. Saxen H, Virtanen M, Carlson P, et at. Neonatal Candida parapsilosis outbreak with ahigh case fatality rate. Pediatr Infect Dis J 1995;14:776-81.

69. Waggoner-Fountain LA, Walker MW, Hollis RJ, et at. Vertical and horizontaltransmission of unique Candida species to premature newborns. Clin Infect Dis1996;22:803-8.

70. Plouffe JF, Brown DG, Silva J, et al. Nosocomial outbreak of Candida parapsilosisfungemia related to intravenous infusions. Arch Intern Med 1977; 137: 1686-9.

7 I. Saiman L, Ludington E, pfaller M, et at. Risk factors for candidemia in neonatalintensive care unit patients. The National Epidemiology of Mycoses Survey study group.Pediatr Infect Dis J 2000; 19:319-24.

72. Huang YC, Lin TY, Lien RI, et at. Candidaemia in special care nurseries: comparison ofalbicans and parapsilosis infection. J Infect 2000;40: 171-5.

73. Benjamin DK, Ross K, McKinney RE, Auten R, Fisher RG. When to suspect fungalinfection in neonates: A clinical comparison of Candida albicans and Candidaparapsilosis fungemia with coagulase-negative staphylococcal bacteremia. Pediatrics2000; 106:712-8.

74. Rex JH, Walsh TJ, Sobel JD, et at. Practice guidelines for the treatment of candidiasis.Infectious Diseases Society of America. Clin Infect Dis 2000;30:662-78.

75. Rex JH, Bennett JE, Sugar AM, et al. A randomized trial comparing fluconazole withamphotericin B for the treatment of candidemia in patients without neutropenia. N Engl JMed 1994;331: 1325-30.

76. Edwards JE, Jr., Bodey GP, Bowden RA, et at. International conference for thedevelopment of a consensus on the management and prevention of severe candidalinfections. Clin Infect Dis 1997;25:43-59.

77. Conly JM, Hill S, Ross J, Lertzman J, Louie TJ. Handwashing practices in an intensivecare unit: the effects of an educational program and its relationship to infection rates. AmJ Infect Control 1989;17:330-9.

78. Larson EL. APIC guideline for handwashing and hand antisepsis in health care settings.Am J Infect Control 1995;23:251-69.

79. Larson E, McGeer A, Quraishi ZA, et at. Effect of an automated sink on handwashingpractices and attitudes in high-risk units. Infect Control Hosp Epidemiol 1991; 12:422-8.

80. Doebbeling BN, pfaller MA, Houston AK, Wenzel RP. Removal of nosocomialpathogens from the contaminated glove. Implications for glove reuse and handwashing.Ann Intern Med 1988;109:394-8.


81. Maki DG. Aseptic technique is very important: maximal barrier precautions duringinsertion reduce the risk of central venous catheter-related bacteremia. Infect ControlHosp EpidemioI1994;15:227-30.

82. Ullman RF, Gurevich I, Schoch PE, Cunha BA. Colonization and bacteremia related toduration of triple-lumen intravascular catheter placement. Am J Infect Control1990;18:201-7.

83. Pearson ML. Guideline for prevention of intravascular device-related infections. Part I.Intravascular device-related infections: an overview. The Hospital Infection ControlPractices Advisory Committee. Am J Infect Control 1996;24:262-77.

84. Cobb DK, High KP, Sawyer RG, et al. A controlled trial of scheduled replacement ofcentral venous and pulmonary-artery catheters. N Engl J Med 1992;327: 1062-8.

85. Pettigrew RA, Lang SD, Haydock DA, et al. Catheter-related sepsis in patients onintravenous nutrition: a prospective study of quantitative catheter cultures and guidewirechanges for suspected sepsis. Br J Surg. 1985;72:52-5.

86. Michel LA, Bradpiece HA, Randour P, Pouthier F. Safety of central venous catheterchange over guidewire for suspected catheter-related sepsis. A prospective randomizedtrial. Int Surg. 1988;73: 180-6.

87. Zinner SH, Denny-Brown BC, Braun P, et al. Risk of infection with intravenousindwelling catheters: effect of application of antibiotic ointment. J Infect Dis.1969;120:616-9.

88. Maki DG, Band 10. A comparative study of polyantibiotic and iodophor ointments inprevention of vascular catheter-related infection. Am J Med. 1981 ;70:739-44.

Chapter 4

Risk Factors for Candida Infections in the IntensiveCare UnitEuropean Perspective

ROSEMARY A. BARNESUniversity of Wales College ofMedicine, Cardiff. United Kingdom

Critically-ill patients are at risk of invasive fungal infections. Recentepidemiological surveys suggest that mycotic diseases represent one of themost rapidly growing infectious complications in the intensive care unit(lCU) setting.The majority of invasive fungal infections in Western Europe involve

opportunist pathogens, such as Aspergillus species, Candida speciesCryptococcus neoformans and Pneumocystis carinii. This is in contrast tomany parts of North America and the developing world where endemicpathogens such as Histoplasma capsulatum, Blastomyces dermatitidis andCoccidioides immitis may cause community-acquired infection andcontribute to the burden of disease. Individual units vary in the risk ofinfection and distribution of fungal pathogens depending on geographicallocation, patient mix, referral patterns, illness-severity and policies of azoleusage and prophylaxis within the institution. However, in all geographicalareas, infections in ICU patients are predominantly nosocomial andcandidiasis accounts for nearly 80% of the total.

Candida species are ubiquitous yeasts that colonize our skin and mucosalsurfaces. C. albicans is part of the endogenous flora of the oropharynx andgastrointestinal tract of normal healthy individuals and may colonize skinsurfaces in small numbers. Other Candida species may colonize hospitalizedpatients and the hands of healthcare workers (HCWs) allowing horizontalspread and the potential for hospital-acquired infection. Many studies haveidentified risk factors for invasive disease, but since these factors arecommon to many critically-ill patients they lack discrimination and are oflimited usefulness in identifying high-risk patients.

46 Chapter 4

Identification of risk factors for mortality is more useful in determiningprophylactic or pre-emptive therapy strategies in this patient group. One ofthe major problems in managing severely-ill patients with possible systemicCandida infections is the difficulty in rapidly establishing the diagnosis, andconsequently starting antifungal treatment in a timely fashion. Pre-emptivetherapy using a risk-based approach is an attractive strategy in critically illpatients. It depends on the results of surveillance cultures to detect sites ofcolonization and accurate selection of very high-risk subgroups of patients.

In addition, growing understanding of the mechanisms of immunoparesisin the critically ill following systemic inflammatory response syndrome,septic shock or major trauma can contribute to better targeting of at-riskpatients.

RISK FACTORS FOR CANDIDIASIS IN THE INTENSIVECARE UNIT

Many risk factors for candidiasis have been described and importantpredisposing factors are listed in Table 1.

Table I. Risk factors for candidiasis

Host-related factors

Mucosal and skin abnormalities or damage

Acute pancreatitis**Multi-organ failure**

Immunosuppression (neutropenia*,corticosteroids)Length ofICU staySeverity of acute illness (APACHE score>20)**Candida colonization*Very low birth weightCentral venous catheterization*Broad-spectrum antimicrobial therapy*Total parenteral nutritionHemodialysisihemofiltration*Bums injuryAnastomotic breakdown or persistentabdominal leak

* independent risk factor; ** risk factor for mortality

Use of central venous catheters, colonization, broad-spectrum antibioticsand hemodialysis are independent risk factors for disseminated Candidainfection (1), but are common to many hospitalized patients. Betterunderstanding of the risk factors for individual groups and knowledge ofwhich risk factors are predictors of mortality (2) will enable more rational

4. Risk Factors for Candida Infections in the Intensive Care Unit 47

use of preventative measures. Length of stay in the unit, while not anindependent risk factor, is often a useful marker since Candida infectionsincrease in frequency with duration of stay and are rare in the first 12 days ofhospitalization on the ICU.The degree and duration of neutropenia is a significant factor in

classically immunocompromised patients (3) while operative time,retransplantation, reoperation and cytomegalovirus infection are relevant toliver and solid organ transplant recipients (4). In neonates, low birth weightis the major factor (5) while on medical and surgical ICUs, severity ofillness, peritonitis and pancreatitis (6,7) may be more useful predictors ofinvasive Candida infection than other commonly cited risk factors.

CANDIDA COLONIZATION

In all risk groups, Candida colonization is an independent risk factor forinfection and precedes invasive disease in most cases. More than 50% ofICU patients will become colonized with Candida species duringhospitalization and distinguishing infection from colonization may bedifficult. The risk of infection increases with the number of sites colonizedand is dependent on the colonizing species. One study demonstrated that15% of patients colonized with C. albicans at one site developed fungemiarising to 17% when two or more sites were colonized (8). However, patientscolonized with C. tropicalis at one site had a 58% risk of subsequentfungemia rising to 100% when two or more sites were colonized with thisspecies (8). Further studies in surgical ICU patients have confirmed thistrend (9) and recommend the use of a Candida colonization index to assessthe degree of colonization. A ratio of ~0.5, calculated from the number ofnon-contiguous sites colonized with the same strain over the number of sitessampled, has been shown to have a positive predictive value of 66% fordetermining infection. The sensitivity can be further increased if the semiquantitative fungal load is simultaneously determined (10). An increasingfungal load in successive specimens is also predictive of invasive disease(7). In neonates, a carriage index representing semi-quantitative yeastconcentrations in saliva or feces has been devised: only neonates with>105

yeast cells/ml saliva or gram offeces developed fungemia (11).Distinguishing colonization from infection is not always straightforward.

Candiduria is not a reliable marker for fungal urinary tract infection andrepresents colonization in most cases. Recent renal or urological surgery orthe presence of complex urological problems increases the significance ofyeast isolation from this site. Isolation from neonates should be viewed withgreater suspicion and may necessitate further investigation. Treatment

48 Chapter 4

directed solely at catheter colonization is unnecessary (12,13), althoughurinary catheter change is recommended (14). Persistent isolation ofCandida species from neonates or patients with known urologicalabnormalities should prompt investigation with imaging techniques toexclude fungal balls and other complications.Isolation of Candida species from respiratory specimens, including

protected brush specimens and lavage fluids is not predictive of fungalpneumonia and represents a colonization site only (15). Currently, fungalpneumonia is a histological diagnosis that is seldom made ante-mortemSite of isolation, density of colonization and identity of species identified

also inform on the degree of risk (16). Isolation of C. tropicalis has astronger correlation with infection than isolation ofC albicans (10). Isolationof a yeast from an intravenous line tip requires careful evaluation with use ofacute phase responses and other markers of infection (17).

MUCOSALAND SKIN DAMAGE

Many risk factors involve altered host defenses that allow fungalovergrowth, while others provide a portal of entry through translocationacross mucosal surfaces or direct invasion via intravenous lines, wounds orbums injuries.Raised gastric pH due to sedation, antacids, H2 antagonists and exocrine

abnormalities may lead to Candida overgrowth in the bowel. Widespread useof broad-spectrum antibiotic agents compounds this. Severity of illness,splanchnic ischaemia following shock, impaired gut mobility or ileus will allcontribute to translocation of yeasts through the bowel mucosa.Total parenteral nutrition is a risk factor over and above the presence of

the central line as intravenous lipids promote fungal growth andtranslocation (18). Enteral feeding is preferable and has been proven toreduce inflammatory markers and disease severity in ICU populations (19).

IMMUNOPARESIS

Admission to the ICU is frequently complicated by an excessive systemicinflammatory response due either to the underlying disease (trauma, surgery,pancreatitis, bums) or as a complication of the underlying illness (e.g. septicshock). Survival of this initial episode may be followed by a compensatoryperiod of immune downregulation associated with monocyte-deactivation,reduced HLA-DR expression and increased risk of infection ('second hit').


Understanding of the immune status of lCU patients and their response tofungal infection is a complex process. Sepsis has a high mortality and may becaused by fungemia although this is infrequent in the lCU setting. Attempts toinfluence this with specific therapies directed at inhibiting the proinflammatory cytokine response have been disappointing. The realization thatcritically-ill patients may display a bimodal pattern of inflammatoryresponsiveness with a prolonged period of immunoparesis associated withmonocyte-deactivation, and vascular endothelial damage has altered ourapproach (20). Most fungal infections in the lCU occur late, and many areassociated with anti-inflammatory cytokine responses, persistent infection andpoor outcome.Protective immune responses to Candida infection are dependent on a ThI

type response that requires the concerted effect ofpro-inflammatory cytokines,including interferon gamma, tumour necrosis factor-alpha, IL-12 and IL-6 inthe relative absence of Th2 type cytokines such as IL-4, IL-IO andtransforming growth factor-beta (21).Fungi themselves are immunomodulatory and may promote Th2 type

responses dependent on fungal load, site of infection and mode of antigenpresentation (22). Strategies to ameliorate this using biologic responsemodifiers, including interferon-gamma or GM-CSF, are attractive but rely onaccurate identification of subgroups of patients who would benefit. Cytokinesand their antagonists have the potential to augment the phagocytic response toinfection and to act synergistically with antifungal drugs to increase cidalactivity (23).

SURGICAL RISK FACTORS

All surgical events have the potential to increase the risk of Candida infectionbut certain procedures and conditions are associated with a significantly higherincidence. Unsurprisingly, gastrointestinal surgery carries a substantial risk ofcontamination/colonization of sterile sites such as the peritoneal cavity.Invasive Candida infections are infrequent if adequate closure and resolutionof the underlying problem is achieved (7). Complications, such as anastomoticbreakdown or recurrent abdominal leakage, are important predisposing factorsthat identify a high-risk subgroup who benefit from antifungal prophylaxis(24). A recent study by Eggiman et al. (25) selected patients who hadundergone recent abdominal surgery complicated by gastrointestinalperforation or anastomotic leakage and randomized them to receiveprophylactic fluconazole at a dosage of 400 mg per day or placebo. Animpressive eight-fold reduction in the relative risk of Candida peritonitis wasseen in the treated group with an associated reduction in hospitalization.

50 Chapter 4

Placebo-treated patients had a one-in-three chance of serious Candidainfection.Acute pancreatitis is a major condition requiring admission to the lCU.

Necrotizing pancreatitis complicates 20% or more of cases and is the majordeterminant of disease severity. It is the main predisposing factor in thedevelopment of infection with gut-derived organisms. Improvements incritical care management have decreased initial mortality, but contributed toprolonged lCU stay and increased use of central venous catheters andantibiotics with a consequent increase in the incidence of fungal infection inthis group of patients (26-29). Indeed, necrotizing pancreatitis represents aunique risk factor for Candida peritonitis (31) and increases mortalitysubstantially (29,31). As described above, immunoparesis may complicatesevere cases and increase risk over and above other factors that predispose toperitonitis (32). Antibiotic prophylaxis is routinely recommended forindividuals with more than 30% necrosis as detennined by abdominal CT scan(33). Increasingly, antifungal prophylaxis is included and fluconazole hasexcellent penetration into pancreatic tissue (34). Concerns remain over theselection pressures this therapy may induce, and in particular the emergingrole of C. glabrata in these infections (35).

RISK FACTORS FOR NEONATAL INFECTION

Numerous studies have identified very low birth weight as the most significantrisk factor for neonatal Candida infection (5). When birth weight is adjustedfor, other specific risk factors including gestational age, APGAR score at 5minutes, disseminated intravascular coagulopathy and intubation becomesignificant (36).Candiduria is more significant in neonates and should prompt suprapubic

urine aspiration and surveillance cultures for other sites of colonization.Persistent isolation requires investigation by renal ultrasound for detection ofechogenic renal fungal balls or abscesses. One study reported an incidenceof renal candidiasis of 42% in neonates with candiduria (37).

ORGAN FAILURE

Renal failure is an independent risk factor for Candida infection (38,39). It isassociated with increased risk ofmortality regardless of what method of renalsupport is implemented. The mechanisms are poorly understood and notdirectly related to uremia (40). Subtle changes in cell-mediated immunefunction may have a role (41,42). Similarly, acute liver failure is associated


with a high incidence of fungal infection, predominantly candidiasis (43).Unsurprisingly, multi-organ failure is a major risk factor for mortality fromCandida infection.

CONCLUSION

Risk factor analysis is only useful if the information can be used to implementevidence-based preventative strategies that reduce infection and improveoutcome. Recent progress has been made in identification of small subgroupsthat benefit from prophylaxis or pre-emptive therapy, but there are many morepatients who could potentially be targeted.Little is known about specific risk factors in burn units. Case reports and

personal experience suggest that patients with esophageal rupture representanother very high risk subgroup (44). The correct approach in these and othergroups is untested.Quantitative surveillance screening is a validated approach, but is time

consuming and costly and may be misleading ifmixed cultures and species arenot identified. Prophylaxis and pre-emptive therapy will increase azole usageand could potentially contribute to antifungal resistance and pathogen shift.Other strategies, such as selective decontamination of the digestive tract (45),may deserve re-evaluation in selected subgroups.

REFERENCES

I. Vincent JL, Anaissie E, Bruining H, et al. Epidemiology, diagnosis and treatment ofsystemic Candida infection in surgical patients under intensive care. Intensive Care Med1998;24:206-16.

2. Fraser VJ, Jones M, Dunkel J, et al. Candidemia in a tertiary care hospital: epidemiology,risk factors, and predictors ofmortality. Clin Infect Dis 1992;15:414-21.

3. Jantunen E, Ruutu P, Niskanen L, et al. Incidence and risk factors for invasive fungalinfections in allogeneic BMT recipients. Bone Marrow Transplant 1997; 19:801-8.

4. Collins LA, Samore MH, Roberts MS, et al. Risk factors for invasive fungal infectionscomplicating othotopic liver transplantation. J Infect Dis 1994;170:644-52.

5. Huang YC, Li CC, Lin TY, et al. Association offungal colonization and invasive diseasein very low birth weight infants. Pediatr Infect Dis J 1998;17:819-22.

6. Petri MG, Konig J, Moecke HP, et at. Epidemiology of invasive mycosis in ICUpatients: a prospective multicenter study in 435 non-neutropenic patients. Intensive CareMed 1997; 3:317-25.

7. Calandra T, Bille J, Schneider R, Mossiman F, Francoli P. Clinical significance ofCandida isolated from the peritoneum in surgical patients. Lancet 1989; ii;1437-40.

8. Voss A, Hollis RJ, Pfaller MA, Wenzel RP, Doebbeling BN. Investigation of thesequence of colonization and candidemia in nonneutropenic patients. J Clin Microbiol1994;32:975-80.

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9. Garbino J, Pittet D. Candida infections in the ICU. Clin Intensive Care 1997;8: 187-200.10. Pittet D, Monod M, Suter PM, Frenk E, Auckenthaler R. Candida colonization andsubsequent infections in critically ill surgical patients. Ann Surg 1994;220:751-8.

II. Van Saene HKF, Damjanovic V, Pizer B, Petros AJ. Fungal infections in ICU J HospInfect 1999;41 :337-8.

12. Sobel 10, Kauffman CA, McKinsey D, et al. Candiduria: a randomized, double-blindstudy of treatment with fluconazole and placebo. Clin Infect Dis 2000;30: 19-24.

13. Kauffman CA, Vazquez JA, Sobel JD, et al. Prospective multicenter surveillance studyof funguria in hospitalized patients. Clin Infect Dis 2000;30: 14-8.

14. Ayeni 0, Riederer KM, Wilson FM, Khatib R. Clinicians'reaction to positive urineculture for Candida organisms. Mycoses 1999;42;285-9.

15. Bauer IT, Torres A. Candida pneumonia. Clin Intensive Care 1999; I0:33-9.16. Munoz P, Burillo A, Bouza E. Criteria used when initiating antifungal therapy against

Candida species in the intensive care unit. Int J Antimicrob Agents 2000; 15:83-90.17. Flanagan PG, Barnes RA. Fungal infections in the intensive care unit. J Hosp Infect

1998;38: 163-77.18. Alverdy JC, Ayos E, Moss GS. Total parenteral nutrition promotes bacterialtranslocation from the gut. Surgery 1988; I04: 185-90.

19. Windsor AJC, Kanwar S, Li AJK, et al. Compared with parenteral nutrition, enteralfeeding attenuates the acute phase response and improves disease severity in acutepancreatitis. Gut 1998;42:431-5.

20. Kox WJ, Volk T, Kox SN, Volk H-D. Immunomodulatory therapy in sepsis. IntensiveCare Med 2000;26:SI24-8.

21. Romani L. Innate and adaptive immunity in Candida albicans infections andsaprophytism J Leuc Bioi 2000;68: 175-9.

22. Mencacci A, Cenci E, Bacci A, et at. Host immune reactivity determines the efficacy ofcombination immunotherapy and antifungal chemotherapy in candidiasis. J Infect Dis2000; 181 ;686-94

23. Romani L. Host immune reactivity and antifungal chemotherapy: the power of beingtogether. J Chemother 2001; 13:347-53.

24. Rex JH, Sobel 10. Preventing intra-abdominal candidiasis in surgical patients. Crit CareMed 1999:27: 1033-4.

25. Eggimann P, Francioli P, Bille J, et al. Fluconazole prophylaxis prevents intra-abdominalcandidiasis in high-risk surgical patients. Crit Care Med 1999:27: I066-72.

26. Grewe M, Tsiotos GG, de-Leon EL, Sarr MG. Fungal infection in acute necrotizingpancreatitis. J Am Coli Surg 1999; 188:408-14.

27. Beger HG, Bittner R, Block S, Buchler M. Bacterial contamination of pancreaticnecrosis: a prospective clinical study. Gastroenterology 1986;91 :433-8.

28. Bassi C. Infected pancreatic necrosis. Int J Pancreatol 1994;16: I-I O.29. Gotzinger P, Wamser P, Barlan M, et al. Candida infection of local necrosis in severe

acute pancreatitis is associated with increased mortality. Shock 2000;14:320-3.30. Hennequin C. Endogenous candidal peritonitis. J Mycol Med 2000;10:21-6.31. Hoerauf A, Hammer S, Muller-Myhsok B, Rupprecht H. Intra-abdominal Candida

infection during acute necrotizing pancreatitis has a high prevalence and is associatedwith increased mortality. Crit Care Med 1998;26:2010-5.

32. Gotzinger P, Sautner T, Spittler A. Severe acute pancreatitis causes alterations in HLADR and CDI4 expression on peripheral blood monocytes independently of surgicaltreatment. Eur J Surg 2000; 166:628-32.

33. Butturini G, Salvia R, Bettini R, et al. Infection prophylaxis in necrotising pancreatitis:an old challenge with new perspectives. J Hosp Infect 2001;49:4-8.


34. Shrikhande S, Friess H, Issenegger C, et at. Fluconazole penetration into the pancreas.Antimicrob Agents Chemother 2000;44:2569-71.

35. Bassi C, Falconi M, Talamini G, et at. Controlled clinical trial of perfloxacin versusimipenem in severe acute pancreatitis. GastroenterologyI998; I 15:1513-7.

36. Saiman L, Ludington E, pfaller M, et at. Risk factors for candidemia in neonatalintensive care unit patients. Pediatr Infect Dis J 2000; 19:319-24.


38. Eubanks PJ, Devirgilio C, Klein S, Bongard F. Candida sepsis in surgical patients. Am JSurg 1993;166:617-20.

39. Blot S, Vandewoude K, Hoste E, Poelaert J, Colardyn F. Outcome in critically illpatients with candidal fungaemia: Candida atbicans vs. Candida gtabrata. J Hosp Infect2001;47:308-13.

40. Ensari C, Ekim M, Ikinciogullari A, Turner N, Ensari A. Are uraemic childrenimmunologically compromised? Nephron 2001;88:379-81.

41. Heidenreich S, Schmidt M, Bachmann J, Harrach B. Apoptosis of monocytes culturedfrom long-term hemodialysis patients. Kidney Intemat 1996;49:792-9.

42. DiScipio AW, Burchard KW. Continuous arteriovenous hemofiltration attenuatespolymorphonuclear leukocyte phagocytosis in porcine intra-abdominal sepsis. Am J Surg1997; 173: 174-80.

43. Rolando N, Harvey F, Brahm J, et at. Fungal infection: a common, unrecognizedcomplication of acute liver-failure. J HepatoI1991;12:1-9.

44. Bauer TM, Dupont V, Zimmerli W. Invasive candidiasis complicating spontaneousesophageal perforation (Boerhaave syndrome). Am J Gastroenterol 1996;91: 1248-50.

45. van Saene HKF, Damjanovic V, Pizer B, Petros AI. Fungal infections in ICU. J HospInfect 1999;41:337-9.

Chapter 5

Laboratory Diagnosis of Fungal Infection in theIntensive Care UnitNorth American Perspective

CHRISTINE 1. MORRISONCenters for Disease Control and Prevention, Atlanta, Georgia, USA

Sophisticated technologies to prolong the lives of severely debilitatedpatients have become more commonplace. Ironically, as a result of thesemedical advances, a population of patients more vulnerable to fungalinfections has been produced. Individuals who would previously have diedfrom major illnesses now survive in a debilitated state, often requiringintensive care for prolonged periods of time. As a consequence, theincidence of invasive fungal infections among critically-ill patients hasincreased significantly over the past decade. Most fungal infections in theintensive care unit (lCU) are caused by opportunistic pathogens, principallyCandida species, which are commonly found as normal commensals of thehuman gastrointestinal tract, skin, and/or mucosa. Less commonly,infections in critically-ill patients are caused by moulds, such as Aspergillusspecies, which are ubiquitous in the environment. These fungi do notordinarily cause invasive infection unless the host is immunocompromisedor otherwise debilitated; therefore, the inherently weakened condition ofmost critically-ill patients, along with the multiplicity of invasive proceduresand immunosuppressive drugs used to treat underlying illnesses in thispatient population, make them particularly susceptible to invasive fungaldiseases.Although antifungal prophylaxis and/or empiric therapy may frequently

be used in high-risk patients, the prognosis remains poor unless infectionsare diagnosed and treated promptly after onset. To complicate matters, signsand symptoms of disease are often non-specific, making a clinical diagnosisdifficult. Often, the only clinical sign is fever unresponsive to broadspectrum antibacterial therapy. Advances in diagnostic radiology,tomography, and ultrasound imaging have improved clinical detection of

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disease, but a specific diagnosis still relies on laboratory confirmation. Thischapter will review the microbiological, serological, histological, andmolecular biological laboratory methods used to confirm the clinicaldiagnosis of invasive fungal diseases most commonly encountered in theICU.

DIAGNOSIS OF INVASIVE CANDIDIASIS IN THEINTENSIVE CARE UNIT

The diagnosis of invasive candidiasis is complicated by a lack of specificsymptoms and clinical signs. In addition, serological tests may be difficult tointerpret. Antibodies to Candida albicans, the most common cause ofinvasive candidiasis, may be detectable in normal individuals as the result ofcommensal colonization of mucosal surfaces. Candida species antigens areoften rapidly cleared from the circulation so that antigen detection tests oftenlack the desired level of sensitivity for an unequivocal diagnosis.Microbiological confirmation is also difficult. Blood cultures are sometimesnegative in cases of deep-seated candidiasis and cultures from the urine ormucosal surfaces do not necessarily indicate invasive disease. To complicatematters, the differing susceptibilities of the various Candida species to azoleantifungal drugs makes identification of the infecting organism to the specieslevel critically important so that appropriately targeted antifungal drugtherapy can be initiated. Histopathologic evidence of tissue invasion inbiopsied host material can confirm a diagnosis but reagents to specificallyidentify the infecting Candida species are not available. In addition, becausepatients at risk for invasive candidiasis may be thrombocytopenic, aninvasive procedure such as a biopsy may be hazardous. Newer molecularbiological tests using polymerase chain reaction (PCR) technology holdpromise but are not yet readily available in the clinical laboratory setting.Also, large clinical trials of the sensitivity and specificity of molecular testsare non-existent. Therefore, non-invasive tests with good sensitivity andspecificity are urgently needed. A combination of serological,microbiological, histological, and molecular biological tests may provide thebest possible laboratory diagnosis at present and methods currently in useand under investigation are reviewed here.

Direct microscopy and culture

In cases of suspected invasive candidiasis, cultures should be made from asmany sources as possible and efforts should also be made to obtain materialfor histopathological examination. Isolation of Candida species from blood,

5. Laboratory Diagnosis ofFungal Infection in the Intensive Care 57Unit

or from other normally sterile sites, provides evidence of invasive infection.The microscopic detection of typical yeast or filamentous forms of Candidaspecies in tissue sections or normally sterile body fluids is also indicative ofinvasive disease. In general, Candida species exhibit a combination ofblastospores, pseudohyphae, and/or true hyphae. Typically, C. glabrataproduces only blastospores and only C. albicans produces true hyphae intissues.Infections with non-albicans species of Candida, including those

resistant to azole antifungal drugs, have been reported to be increasing (1).Therefore, identification of isolates to the species level has becomeespecially important. Carbohydrate assimilation and fermentation tests,together with Dalmau plate morphology, have been traditionally used todifferentiate most of the medically important Candida species. More rapidand less laborious culture identification methods have been developed inrecent years and include tests such as the RapID Yeast Plus System(Innovative Diagnostic Systems, Norcross, Georgia) which containsconventional and chromogenic substrates and requires only 4-5 hours tocomplete (2-4), the Fongiscreen test (Sanofi Diagnostics Pasteur, Marnes-laCoquette, France) (5,6), and the automated Rapid Yeast Identification Panel(Dade Microscan, Inc., West Sacramento, California) (7,8). Although suchtests can identify an isolate in as little as one day, most of these tests aremore accurate in the identification of common yeast pathogens than in theidentification of rarer yeast pathogens. For example, in one study, the RapIDYeast Plus System correctly identified 96% of common yeasts, but only 79%of rarer Candida species and only 75% of other uncommon yeasts (9).Perhaps the most convenient and popular methods for Candida species

identification consist of strips or plates for carbohydrate assimilation and/orenzyme detection which are commercially available in various formats froma number of different companies. These systems include, but are not limitedto, the API 20C AUX (bioMerieux-Vitek, Inc., Hazelwood, Missouri), theAPI Candida (bioMerieux, Marcy-l'Etoile, France), the Auxacolor (SanofiDiagnostics Pasteur), and the Uni-Yeast-Tek kit (Remel Laboratories,Lenexa, Kansas). These tests use an increase in turbidity (API 20C AUX) orthe production of color (API Candida, Auxacolor, Uni-Yeast-Tek) in each ofa series of wells containing different substrates. The particular patternproduced is then translated into a numerical code that is deciphered using themanufacturer's guide book. Similar to the rapid tests described above, thesetests give excellent results with the more common species of Candida andgenera of yeasts (99.8% for Uni-Yeast-Tek, 98% for API 20C AUX, 81-91%for Auxacolor, and 79-92% for API Candida) (10-14). The Auxacolor andAPI 20C AUX tests are also relatively useful for identifying common germ-

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tube-negative Candida species (i.e., the accuracy of these tests ranged from75-93%) (10,15). However, identifications of less common Candida speciesand genera are less accurate (i.e., the Auxacolor and API Candida tests failedto identify C. norvegensis, C. catenulata, C. haemulonii, and C. dubliniensisand the API 20C AUX gave only 90% accurate identifications of isolatesbelonging to genera of Cryptococcus, Trichosporon, and Geotrichum) (lOB). Further, although the API Candida system correctly identified 92% of146 clinical isolates, 23 required supplemental biochemical or morphologicaltests for unequivocal confirmation (13). The Auxacolor test was consideredto be simpler, more rapid to set up, and easier to interpret than the API 20CAUX and yet it was comparable in cost (15).The development of a chromogenic medium (CHROMagar Candida,

CHROMagar Co., Paris, France) which incorporates chemical dyes intosubstrates in a solid medium to differentiate species of Candida by the colorand texture of the growth produced (c. albicans, glossy, greenlblue green; C.tropicalis, glossy, blue/purple; C. krusei, ruffled, pink) has been particularlyhelpful for the presumptive identification of these species (16,17).CHROMagar Candida medium is especially valuable for the differentiationof mixed cultures which would ordinarily be missed during conventionalplating on solid media (18,19). Some researchers have reported that thismedium can also be used to differentiate C. glabrata from other yeastspecies (19-21). In contrast, others reported that it cannot be used for thispurpose because C. kefyr, C. lusitaniae, C. guilliermondii, C. famata, c.rugosa, C. utilis, C. robusta, C. pelliculosa, Cryptococcus neoformans, andSaccharomyces cerevisiae all produce the same type of glossy pink coloniesas C. glabrata, leading to misidentification (22-24). Although CHROMagarCandida was recently reformulated (BBL, Becton Dickinson, Cockeysville,Maryland), no significant differences in the growth rate or colony size wereobserved for most species and no differences in the capacity to differentiatebetween colonies of C. albicans, C. tropicalis, and C. krusei were reportedfor the new formulation compared to the previous one. However, all C.albicans isolates gave a lighter shade of green on this medium compared tothe old formulation whereas C. dubliniensis isolates gave the same typicaldark green color on both the old and new formulations (25). It was thereforeproposed that the new medium could not only differentiate between C.albicans, C. tropicalis, and C. krusei but could also differentiate C. albicansfrom C. dubliniensis. Others have incorporated fluconazole into theCHROMagar Candida medium to identify not only the Candida speciespresent but to simultaneously detect resistant isolates (26,27).Additional methods for species identification include automated

biochemical systems such as the ill 32C strip system (bioMerieux), theVitek Yeast Biochemical Card system (bioMerieux-Vitek, Inc.), the Vitek 2


ID-YST card system (bioMerieux-Vitek, Inc.), the Quantum II (AbbottLaboratories, Irving, Texas), and the Biolog YT MicroPlate system (Biolog,Hayward, California) to mention only a few. A variety of other colorimetricand enzymatic systems as well as fatty acid analysis and physicochemicalspectroscopic methods, details ofwhich are beyond the scope of this chapter,can be found described in a recent comprehensive review of these subjectsby Freydiere et al. (28).Isolates used in all of the above studies required subculturing from the

primary isolation medium for at least 24 hours before inoculation into thespecies identification test kit. However, in one study (29), the Auxacolorsystem was used successfully after inoculation of test strips with fluidobtained directly from blood culture bottles. This procedure thereby omittedthe time-consuming subculturing step. Forty-three of 44 isolates recovered,representing seven yeast species, were correctly identified by directinoculation of the Auxacolor system (29). Going one step further, Makimuraet al. (30) described a blood lysate method to directly detect yeasts withoutany culturing. Blood samples were obtained from immunocompromisedpatients presenting with fever who were also clinically suspected of having afungal infection. Yeast cells could be easily differentiated from blood celldebris by size, shape, and smooth but rigid outline in six of eight samplesafter periodic acid-Schiff (PAS) staining (30). However, given that only 50%or less of blood cultures from patients with invasive candidiasis are positiveeven when lysis centrifugation tubes, or improved blood culture bottlesystems, which are reported to increase yeast recovery from blood, are used(31-33), the likelihood of detecting Candida cells directly from whole bloodwould be low even after lysis of blood cells and PAS staining.Despite the insensitivity of blood cultures, Candida species are not

especially fastidious organisms and can be grown on many commonlaboratory media (34). Several advances in blood culturing techniques haveoccurred which appear to have improved the sensitivity and/or reduced thetime required to obtain a positive blood culture. These include thedevelopment of lysis centrifugation tubes, biphasic media, and automatedmonitoring of blood culture bottles.Compared to culturing from ordinary vacutainer blood collection tubes,

the lysis centrifugation system (Wampole Laboratories, Cranbury, NewJersey; originally known as the DuPont Isolator tube) increases the yield ofCandida species recovered from blood by using detergent to release fungitrapped within host phagocytic cells. The lytic mixture not only lyses thehost cells but also inactivates both complement and some antimicrobialagents which could be harmful to the viability of the fungus. Tubes arecentrifuged and the resultant pellet is then plated onto solid medium. Any

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number of solid media have been tested for this purpose and some havesuggested that chocolate agar was a good medium for the rapid (3 day)recovery ofmost yeasts (35,36). Inhibitory mould agar is commonly used forthe recovery ofmoulds (36). In early studies, lysis centrifugation tubes werealso reported to be superior to routine blood culture bottles for the recoveryof yeasts (32,37). Dorn et al. (37) found that the use of lysis centrifugationtubes resulted in the recovery of yeasts in 22 cases versus recovery in only10 cases when blood culture bottles alone were employed. The mean time todetection of positive cultures was 1.8 days for the lysis centrifugation tubesand 3.7 days for blood culture bottles. In this instance, blood culture bottleswere vented and contained supplemented peptone medium. Compared toblood culture bottles, the superiority of the lysis centrifugation system wasalso demonstrated when vented Columbia broth (38) or aerobic tryptic soybroth bottles were used (39,40). The mean time to positivity for the lysiscentrifugation tubes compared to the blood culture bottle systems tested was1.9 days versus 2.8 days.In other studies (41), it was reported that blood cultures using lysis

centrifugation tubes were positive in seven of nine patients (78%) infected atmore than three deep-tissue sites whereas blood cultures were positive inonly five of 28 patients (28%) infected at only one site. Therefore, a directcorrelation between tissue burden in deep-seated candidiasis and thefrequency of fungemia detected using lysis centrifugation tubes wasdemonstrated (41). In addition, the mean time to obtain a positive bloodculture using the lysis centrifugation system was faster for patients withmultiple organ involvement (2.6 days) than for those with single organinvolvement (3.2 days). Others have not advocated the routine use of lysiscentrifugation tubes because of the exceptionally high rate of false positivesand of contamination discovered during their use (42). Although theseresearchers stated that blood samples from the lysis centrifugation tubeswere processed in a biosafety class II hood according to the manufacturer'sinstructions, it was not clear whether the complete processing equipment(Isostat device, Wampole), designed to reduce or eliminate contaminationproblems, was employed. Nonetheless, the main disadvantage of the lysiscentrifugation system is that it is labor-intensive, precluding routine use insome laboratories.The use ofbiphasic culture media has been shown to improve the yield of

Candida species recovered from blood compared to routine broth cultures(38,43-45). The use of vented, biphasic tryptic soy broth improved the meantime to recover Candida species from the blood to 2.3 days compared to 3days for conventional broth culture (45). Similarly, Kiehn et al. (38) reportedthat use of brain heart infusion (BHI) broth in a vented biphasic systemimproved the time to detection compared to routine broth culture and that the

5. Laboratory Diagnosis ofFunga/ Infection in the Intensive Care 61Unit

biphasic system detected fungemia first in 29 cases (73%). Roberts andWashington (46) also found vented BHI in a biphasic system to be superiorfor yeast recovery compared to a conventional broth system (in this case,vented soybean casein digest medium) and that the time to detection wasshorter (2.6 days versus 5.2 days).Compared to biphasic culturing methods, the lysis centrifugation system

has been demonstrated by several researchers to result in a higher frequencyof yeast recovery and more rapid detection of fungemia (47,48). GuerraRomano (48) reported that the lysis centrifugation method detected 178 of199 (89.4%) blood cultures whereas the Septi-Chek biphasic system (RocheDiagnostics, Nutley, New Jersey) detected only 119 (59.7%). The mean timeto recovery was also shorter for the lysis centrifugation system (2.2 days)than for the Septi-Chek system (4.9 days). Bille et a/. (47) reported thatduring 37 episodes of fungemia, the lysis centrifugation system, incomparison to a vented biphasic BHI broth system was the only system todetect nine (24%) episodes of fungemia and was the first system to detect 31(84%) of these events. It was suggested that agitation ofbiphasic bottles mayimprove detection of fungemia to an extent similar to the lysis centrifugationtubes (49). Permanently vented biphasic bottles also increased the recoveryof yeasts from blood cultures compared to transiently vented bottles (46,47).Recent improvements in the formulation of blood culture media,

especially those containing resins to absorb out residual antimicrobial drugsas well as substances normally found in blood which are inhibitory to fungalgrowth, in conjunction with newer automated blood culture bottle systems,have made recovery of Candida species from blood culture bottles aseffective as that from lysis centrifugation tubes (36,50-52). For example, theautomated BACTEC high volume fungal media system (Becton DickinsonDiagnostic Instrument Systems, Sparks, Maryland) and the BacT/Alertsystem (Organon Teknika Corp., Durham, North Carolina) were found tohave comparable sensitivity to the lysis centrifugation system for therecovery of Candida species (53-55). The BACTEC NR600 aerobic 6Ablood culture system was found to be comparable to 1.5 ml pediatric lysiscentrifugation tubes for the recovery of fungemia in children (52). Sixtyisolates (44 C. a/bicans, 12 C. parapsi/osis, and four C. tropica/is) wererecovered from both systems, 16 (eight C. a/bicans, five C. parapsi/osis, andone each of C. tropicalis, C. /usitaniae and Rhodotoru/a g/utinis) wererecovered from lysis centrifugation tubes only, and 13 (10 C. a/bicans, oneC. parapsilosis, and two Cr. neoformans) were recovered from NR6A bloodculture bottles only (52). In general, however, the lysis-centrifugation systemremains superior to blood culture systems for the recovery of fungi otherthan Candida species (i.e., recovery of Cr. neoformans and dimorphic

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moulds has been generally less satisfactory using blood culture bottles thanlysis centrifugation tubes) (32,54,56).Early blood culture bottle systems incorporated 14C-Iabeled metabolic

precursors into the growth medium so that as microorganisms grew, 14COZwas liberated into the bottle headspace and the amount of 14COZ producedwas determined periodically as a measure of cell growth (BACTEC 460,Becton Dickinson Diagnostic Instrument Systems). When a predefinedthreshold of growth was reached, a Gram stain and subculture wereperformed. In the early 1980s, radiometric 14COZ detection was replacedwith infrared spectrophotometry (BACTEC 660, 730, and 860). In bothsystems, the headspace atmosphere was only periodically sampled.Nonetheless, these systems had a distinct advantage over routine culturing ofblood collected into conventional vacutainer tubes (Becton DickinsonVacutainer Systems, Cockeysville, Maryland). For example, one studycompared the capacity of the vacutainer system to that of the automatedBACTEC NR system for the detection of candidemia. The mean timerequired for the detection of growth by the vacutainer system was 7.6 dayscompared to 4.1 days for the BACTEC NR system. Whereas the vacutainersystem detected 56% of cases, the BACTEC NR system detected 94% (57).Perhaps the single most important improvement in the recovery of yeasts

from blood culture bottles was the institution of automated systems withcontinuous growth monitoring. Either colorimetric (BacT/Alert, OrganonTeknika Corp.) or fluorescent (BACTEC 9240, Becton DickinsonDiagnostic Instrument Systems; Vital, bioMerieux-Vitek, Inc.) monitoringcan now be conducted automatically and electronically at approximately 10minute intervals. Continuously monitored manometric systems to detectgrowth also exist (ESP, Difco, Detroit, Michigan and O.A.S.LS., UnipathLtd., Basingstoke, UK). A comprehensive review of these systems can befound in Reimer et al. (56).Other than by the addition of resins to the culture medium, the sensitivity

of blood culture bottles may also be improved by simply increasing thevolume of blood introduced into the bottles (58,59), changing the ratio ofblood volume to culture medium volume (60), or by venting bottles so thatcultures grow aerobically rather than anaerobically (43,61-64). Newer bloodculture bottles, designed so that venting is not necessary, have also beendeveloped and appear to give similar or better results compared to the oldervented bottle systems (65,66). Incubation temperature can also effect fungalcultures and yeasts grow best at 37°C whereas moulds tend to do better atreduced temperatures (25-30°C). The composition of the culture mediummay also improve sensitivity of recovery. Culture media that have been usedsuccessfully for the growth of yeasts and moulds from blood include trypticsoy, Columbia, thioglycollate, and BHI broth (56). BACTEC aerobic-


hypertonic 8B medium was demonstrated to be superior to BACTEC aerobic6B medium for the recovery ofCandida species in the BACTEC 460 system(67). Of 137 positive blood culture sets, yeasts were detected in 120 (88%)of the bottles containing 8B medium and this medium was the only positivemedium in 35 (26%) of the sets. In comparison, yeasts were detected in 102(74%) of the bottles containing 6B medium and this medium was the onlypositive medium in 17 (12%) ofthe sets (67).Thus far, discussions have addressed improving the recovery of Candida

species from blood culturing systems. However, when blood cultures arepositive, this may only indicate a transient, catheter-related candidemia,although even a single positive blood culture in patients at high risk ofinvasive disease should not be ignored. Because delayed initiation ofantifungal therapy can have devastating consequences for the patient withinvasive candidiasis, many physicians now recommend empiric antifungaltreatment after recovery of only one positive blood culture (68-70). Studiesto differentiate central venous catheter-related candidemia from invasivedisease have used correlations between tissue invasiveness and the detectionof circulating Candida species antigen by dot immunobinding assay topredict true invasive disease (71). However, multiple blood cultures onsuccessive days, especially after removal of or in the absence of centrallines, are compelling evidence of invasive disease.Body fluids other than blood may also be culture positive for Candida

species. Although the majority of patients with candiduria are asymptomatic,positive urine cultures, in the absence of indwelling urinary catheters, whichyield>1 x 104 cfu/ml should raise suspicion of infection. However, Candidaspecies may be absent from the urine even in disseminated infection and viceversa (72). In a prospective study in which candiduria was followed in 861hospitalized patients from 10 medical centers over a 10-week period or untildischarge, only 94 of 861 patients (11%) with funguria had no underlyingillness (73). Documented clinical outcome data was available for 530 ofthese patients and 105 (19.8%) of these patients died. Therefore, althoughcandiduria may not be a specific marker for disseminated candidiasis, it hasbeen proposed that it is an indicator for poor clinical outcome resulting fromthe multiple serious underlying diseases and advanced age of the populationpossessing this condition (72).

Immunohistology and molecular histology

The detection of typical blastospores and pseudohyphae of Candida speciesin histochemically-stained tissue sections is diagnostic for invasivecandidiasis. However, the production of fluorescent antibodies specific for

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the identification of individual Candida species, whether in clinical materialsor in culture, has proved extremely difficult. Generic reagents which reactacross Candida species, however, have been developed and can be used todifferentiate infections by Candida species from those of other fungi (74). Arecent study used an IgG1 monoclonal antibody, 3H8, directed against C.albicans cell wall mannoprotein, to specifically recognize C. albicans inculture and in paraffin-embedded tissue sections using immunofluorescentand immunohistochemical staining (75). This antibody preferentiallydetected mycelial forms and, to a lesser extent, blastospores of C. albicansand did not react with any other Candida species tested. This monoclonalantibody was originally produced for use in a latex agglutination kit (Bichrolatex albicans, Fomouze Diagnostics, Asnieres, France) for the rapididentification of C. albicans in culture (75-77). Differentiation of C. albicansfrom C. dubliniensis has been reported by use of an indirectimmunofluorescence test which separated these organisms based ondifferential localization of antigens on C. dubliniensis blastospores and on C.albicans germ tubes (78). In this study, anti-C. dubliniensis serum wasadsorbed with C. albicans blastospores so that no reactivity was observedagainst C. albicans or several other Candida species. However, crossreactivity was observed with blastospores of C. krusei and Rhodotorularubra.Fluorescent in-situ hybridization (ISH), using oligonucleotide probes

directed against the 18S rRNA gene of Candida species, has been used todifferentiate C. albicans from C. parapsilosis in tissues of infected mice(79). The C. albicans probe detected fungal cells in tissue sections of thekidney, spleen, and brain ofmice infected with C. albicans, but not in tissuesfrom mice infected with C. parapsilosis. The C. parapsilosis probe detectedfungal cells in tissues from mice infected with C. parapsilosis, but not intissues from mice infected with C. albicans. In addition, the C. albicansprobe could detect as few as three C. albicans cells per 500 ~l of spikedhuman blood after a lysis-filtration assay and ISH.

Antibody detection in the diagnosis of invasive candidiasis

The clinical usefulness of antibody detection for the diagnosis of systemiccandidiasis has been limited by false-negative results in immunosuppressedpatients who produce low or undetectable levels of antibody and by falsepositive results in patients colonized at superficial sites. In a study conductedto evaluate the usefulness of antibody detection by double immunodiffusion(ill), 214 patients admitted to the leu of a university hospital were followedfor the development of invasive candidiasis (80). Thirty-six patients (16.8%)


developed invasive candidiasis but the sensitivity and specificity of the illtest was only 29 and 67%, respectively. These data suggest that the ill test isnot very helpful for the diagnosis of invasive candidiasis in this patientpopulation.

In an attempt to reduce false-positive results, several researchers havedeveloped tests to detect antibodies directed against cytoplasmic antigens,based on the assumption that the host would not be exposed to intracellularantigens except during invasive disease. Unfortunately, in a study of patientsundergoing induction chemotherapy for acute leukemia, antibody to a major54.3 kDa cytoplasmic antigen described by Jones et al. was infrequently(25%) detected in cases of disseminated candidiasis (81-84) and othersfound increases in antibody titers in 10% of patients without candidiasis(85). In contrast, EI Moudni et al. (86) described highly successful detectionof antibodies to a purified 52 kDa metalloprotein of C. albicans in anenzyme-linked immunosorbent assay (ELISA). The authors did not,however, specify whether the patients were immunocompromised.Nonetheless, at a cut-off absorbance of 0.425, test sensitivity was reported tobe 83% and specificity to be 97%. It was therefore suggested that thisaminopeptidase may be a useful antigen for the detection of antibodiesformed during invasive candidiasis.Studies describing the usefulness of antibody detection are very few to

date and, in general, it would seem that immunosuppressed patients often failto produce antibodies or their antibody production can be variable. Thesefactors make diagnostic tests to detect antibodies unhelpful for the diagnosisof systemic candidiasis in this patient population. However, such patientsmay be in antigen excess, making the detection of antigens a potentiallymore successful strategy for the diagnosis of candidiasis for this patientgroup.

Antigen detection in the diagnosis of invasive candidiasis

Numerous circulating antigens have been used as potential targets for thediagnosis of invasive candidiasis. One such antigen is an inducible,extracellularly secreted aspartyl proteinase (Sap) produced by C. albicansand some other Candida species. Sap was first described by Staib in 1965and has since been studied extensively as a virulence factor in the invasionand dissemination of C. albicans in animal models of infection (33,87-90).The theoretical usefulness of Sap as a diagnostic antigen stems from thehypothesis that, because Sap is an inducible enzyme produced during activetissue invasion (91,92), its production should correlate with invasive diseaseand not simple colonization. In a rabbit model of disseminated candidiasis,

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Sap antigenuria was followed during disease progression using a competitivebinding inhibition enzyme immunoassay (EIA) (33). After 24 hours, urinefrom eight rabbits demonstrated significant inhibition in the EIA (15 ±7%)and inhibition increased daily to a peak of 46% by day 3 post infection indirect proportion to disease severity. The EIA was negative when urine wastested from rabbits with gastrointestinal colonization with C. aibicans, orfrom rabbits infected with Aspergillus fumigatus, Cr. neoformas, otherCandida species or bacteria (33).Ruchel et al. (93) examined serum samples from patients for the utility of

Sap detection as an aid to the diagnosis of invasive disease. Using anti-Sapantibodies in an EIA format, the sensitivity for detection was low (positive in50% of suspected plus confirmed cases) (93) and may be the result of theformation of complexes between Sap and alpha-2-macroglobulins in thecirculation (94). Therefore, detection of Sap in serum did not appear to be aspromising as detection in urine.More recently, Na and Song (95) compared three different ELISAs for

their efficacy for the detection of either anti-Sap antibodies or Sap antigen inserum. Two Sap-detection formats were tested: an inhibition ELISA and anantigen capture ELISA. Both antigen detection tests used a monoclonalantibody, CAPl, which was reported to be specific for C. aibicans Sap.These authors analyzed 33 serum samples collected retrospectively fromculture-confirmed cases of invasive C. aibicans infection and includedserum samples from 12 patients with aspergillosis and 13 from healthycontrol subjects. The sensitivities and specificities, respectively, were 70 and76% for the antibody detection assay and 94 and 92% for the antigen captureELISA. The sensitivity and specificity of the inhibition ELISA was evenhigher: 94 and 96%, respectively. These data suggest that the inhibitionELISA could be useful for the diagnosis of invasive C. aibicans infections.Further work is warranted to validate these findings in a well-controlled,prospective study.Another potential diagnostic antigen, which has received much attention,

is the major cell wall mannoprotein, or mannan, of C. aibicans. Dissociationof antigen-antibody complexes is necessary for the optimal detection ofmannan in the circulation. This antigen is heat stable and resists boiling,proteinase treatment, and acidic pH (33). Therefore, antigen-antibodycomplexes are routinely dissociated by boiling in the presence of EDTA orby enzymatic treatment. Bailey et al. (96) detected mannan in the serum of17 of 21 patients with disseminated candidiasis when specimens were treatedwith pronase and heat, whereas only three of 21 patients were positive if nodissociation step was included. Mannan is rapidly cleared from thecirculation resulting in low serum concentrations (usually 100 ng/ml or less)and multiple serum sampling is required for optimal detection. Mannanemia


occurs in approximately 31-90% of patients with disseminated candidiasisdepending on the frequency of sampling, the spectrum of the underlyingdisease, the degree of immunosuppression, the serotype of C. albicans, theCandida species involved, the definition of disseminated candidiasis, thespecificity and titer of the capture antibodies, and the immunoassay method.Many laboratories have attempted to use radioimmunoassay (RIA), EIA,latex agglutination (LA), or reverse passive latex agglutination (RPLA) todetect circulating mannan (33,97,98).Methods developed in research laboratories, including sandwich EIA

(97-100) and RPLA (96,101), have moderate sensitivity but good specificityfor disseminated disease. In a retrospective study of patients with cancer, thesandwich EIA showed a sensitivity of 65% and a specificity of 100% (99).More recently, Sendid et al. (102) examined two EIAs for the serologicaldiagnosis of invasive candidiasis. One test detected anti-mannan antibodiesand the other, circulating mannan antigen. Of 162 serum samples from 43patients with culture-proven C. albicans candidiasis, 43 samples werepositive for mannan antigen and 63 had what was considered to besignificant anti-mannan antibody levels. Although 36 (84%) of the 43patients had at least one of these tests positive, only five serum samples werepositive in both tests simultaneously. The sensitivities and specificities were40 and 98% for the antigen detection test and 53 and 94% for the antibodydetection test, respectively. Sensitivity and specificity was increased to 80and 93%, respectively, when results of both tests were combined. It wastherefore suggested that both tests should be implemented for routinediagnosis of candidiasis.Fujita and Hashimoto (100) compared the sensitivity of the sandwich

EIA format to that of the RPLA format using the same capture antibodies forboth. They found that whereas the sensitivity of the RPLA was 38%, that ofthe sandwich EIA was 74% (100). In other studies, the RPLA test detectedserum mannan in 78% of leukemia patients with disseminated candidiasis(101) and, in another study, in 13 of 18 (72%) of patients for whomdisseminated candidiasis was confirmed by biopsy, autopsy, or persistentcandidemia during granulocytopenia (96).Several commercial LA kits are available (LA-Candida Antigen

Detection System, Immuno-Mycologics, Norman, Oklahoma; PastorexCandida, Sanofi Diagnostics Pasteur; Bichro-latex albicans, FomouzeDiagnostics), but the sandwich EIA is currently only available in researchlaboratories (33,74,103). Hybridtech, Inc. (San Diego, California) developeda membrane immunoassay that has been discontinued and a commercialsandwich EIA is under development in Japan.

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Detection of cytoplasmic proteins of C. albicans have also been useddiagnostically by a number of researchers employing a variety of testformats (104-108). The two predominant cytoplasmic proteins described todate include a 47 kDa protein which is a breakdown product of a 90 kDaheat-shock protein (HSP-90) and a 48 kDa protein later found to be a C.albicans enolase (105,108-110). Western blot analysis does not resolve theantigens in the 47 to 52 kDa range unless monoclonal antibodies thatspecifically recognize the enolase antigen are applied (111). The 47 kDaantigen was detected in the serum of 77% of neutropenic patients withdisseminated candidiasis using an enzyme-linked dot immunobinding assay(104) which proved to be more sensitive than a RPLA test for the sameantigen (112).Preliminary studies in mice and rabbits using an EIA format revealed that

the presence of the 48 kDa antigen in serum correlated with disseminateddisease, was positive in the absence of candidemia, and declined withantifungal therapy (113). The assay was commercialized as a doublesandwich liposomal assay using murine IgA monoclonal antibody adsorbedto a nitrocellulose membrane (DirectigenJ_2_3 Disseminated Candidiasis Test,Becton Dickinson, Philadelphia, Pennsylvania). Serum was added and thenpolyclonal rabbit anti-C. albicans enolase was applied and detected with aliposome-containing rhodamine dye and coated with goat anti-rabbit IgG(113). Results of a multicenter study conducted at cancer centers over a twoyear period revealed a sensitivity per sample of 54% whereas when multiplesamples were tested, detection of antigenemia was improved to 85% (114).No doubt multiple sampling will be necessary to optimize antigenemiadetection. Unfortunately, this test is no longer available commercially.Unlike the previously described antigens which have been identified and

chemically purified, Gentry et al. (115) described detection of a structurallyuncharacterized, 56°C-labile antigen, by RPLA. Latex particles weresensitized with serum from rabbits immunized with whole, heat-killed C.albicans blastospores. The test was commercialized as the Cand-Tec test(Ramco Laboratories, Houston, Texas) and has been the subject of severalinvestigations (97,98,101,112,116-118). The circulating antigen was notonly heat-sensitive but also susceptible to pronase, 2-mercaptoethanol, andsodium periodate treatment, suggesting that the molecule may be aglycoprotein. The sensitized latex particles could not agglutinate mannan(115) and it has been suggested that the assay may detect a neoantigenderived from C. albicans after host processing or a host antigen which crossreacts with those of C. albicans. Although relatively easy to perform, the testappears to lack sensitivity when an antigen titer of 1:8, which excludes mostfalse-positive results, is used (97,98,101,112,116-118). In a study of 10patients with disseminated candidiasis, only 28 out of 108 serum samples


(26%) were positive by this test at a titer of>1:8 (112). Unfortunately, testspecificity is also low. For example, in a retrospective study, the test gavefalse-positive results (titers ~1 :8) in four of six patients with transientcandidemia, in one of 20 healthy individuals with rheumatoid factor, and inone patient who had a positive Cryptococcus antigen test (97). Morerecently, Pallavicini et al. (80) conducted a study to evaluate the usefulnessof antigen detection by the Cand-Tec LA test. During a period of42 months,214 patients admitted to an ICU were followed for the development ofinvasive candidiasis. Although 36 (17%) of patients developed invasivedisease, the positive predictive value of the Cand-Tec test was low (1317%). Therefore, studies to date suggest that the Cand-Tec test does notprovide sufficient predictive value for a reliable diagnosis of candidiasis.Although not found to be a reliable indicator of invasive candidiasis, one

study found the Cand-Tec test to be a useful predictor for timing theinitiation of antifungal drug therapy (119). The assay was performed seriallyon 10 patients with acute leukemia during 12 febrile episodes followingpost-remission chemotherapy. Febrile neutropenia after antileukemicchemotherapy and an increased Cand-Tec titer relative to that measuredbefore antileukemic chemotherapy were used as indicators to administerintravenous azole antifungal drug therapy. In nine (82%) of the 11 evaluablecases, antifungal therapy was effective and the Cand-Tec titers declined toless than or equal to baseline. In contrast, for two cases where antifungaldrug therapy failed, the Cand-Tec titers did not decline. The Cand-Tec testwas therefore suggested to provide a means to prevent excess use ofantifungal agents and to thereby reduce the potential development of azoleresistant Candida infections.

D-arabinitol detection for the diagnosis of invasivecandidiasis

Another approach to the diagnosis of invasive candidiasis involves thedetection in serum or urine of a metabolite, D-arabinitol, produced by theinfecting organism. This is a five-carbon sugar alcohol produced by most ofthe major medically important Candida species except for C. krusei andperhaps C. glabrata (120). However, both the D- and L-enantimers ofarabinitol are also found in human body fluids. It is uncertain if the humanhost produces one or both enantimers of arabinitol or if baseline levels inserum and urine are the result of dietary or microbial arabinitol absorbed bythe gut (120,121). Nonetheless, natural host serum arabinitol accumulatesduring renal insufficiency so that D-arabinitollevels need to be reported as aD-arabinitollcreatinine ratio in order to compensate for this occurrence

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(122). Alternatively, as only the D-enantimer is found in Candida speciesand is speculated to be responsible for the elevated levels of D-arabinitolwhich occur during invasive candidiasis (123), it is possible to use gas-liquidchromatography (GLC)-negative chemical ionization mass spectrometry tocompute the D-arabinitollL-arabinitol ratio as another method to normalizethe D-arabinitol concentration (124). Levels in serum and urine are thenreported as D/L-arabinitol ratios (124,125).D-arabinitol was first discovered in the serum of patients with invasive

candidiasis during GLC analysis of serum to detect mannose (120,126).Improvements in gas chromatography (GC) methods to detect D-arabinitolthen led to the development of GC-mass spectrometry (MS) methods (120).These were validated by Roboz et al. (127) who first used GC-MS withpositive chemical ionization and found elevated serum D/L-arabinitol ratiosin 10 of 12 (83%) confirmed cases of invasive candidiasis. Negativechemical ionization, used in a later study, improved test sensitivity: 15 of 16(94%) patients demonstrated elevated D/L-arabinitol ratios (124).Christensson et al. (125) conducted a prospective GC-MS study

analyzing the D/L-arabinitol ratios in urine of 10 children with confirmedinvasive candidiasis. In this study, all patients were positive. Twelve of 23(52%) patients undergoing empiric antifungal chemotherapy for suspectedfungal infection and four of 67 (6%) children not receiving antifungaltherapy were also positive. Most interestingly, the D/L-arabinitol ratios werepositive a mean of 12 days before the first positive blood culture was drawnor before empiric therapy was initiated. As urine is a very non-invasiveclinical specimen, it was speculated that an early rise in the D/L-arabinitolratio could be used as a basis for the institution of antifungal drug therapy aswell as in the diagnosis of invasive disease.Despite the promise demonstrated by the measurement of D/L-arabinitol

ratios by GC-MS, this method is generally very slow (only a few samplescan be analyzed per day), the equipment is very expensive, and analysis isnot only technically demanding but too cumbersome for routine clinical use.Therefore, other methods, which use either enzymatic-fluorometric orenzymatic-colorimetric detection of D-arabinitol have been developed (128131).The enzymatic-fluorometric detection format gives somewhat higher

values than the GC methods but these differences were not significant (128131). This method uses the enzyme D-arabinitol dehydrogenase (theenzymatic portion of the assay) to convert D-arabinitol to D-ribulose. Theconversion of added NAD to NADH during the enzymatic reaction can thenbe detected spectrofluorometrically (the fluorometric portion of the assay)(120,128, 132).


Switchenko et al. (130) used a semi-automatic enzymatic-colorimetricassay in which NADH-dependent endproducts were measured. In an attemptto reduce cross-reactions with D-mannitol, these authors used a more highlypurified arabinitol dehydrogenase enzyme than that used previously.Whereas previous enzymes were derived from bacteria, this enzyme wasderived from C. tropicalis and was cloned and expressed in Escherichia coli(131). In this assay, the D-arabinitol is converted to D-ribulose by therecombinant arabinitol dehydrogenase in the presence ofNAD. The resultantNADH produced reduces iodonitrotetrazolium in the presence of diaphoraseto form a blue-black formazan dye. This dye can then be detectedspectrophotometrically at 500 nm. The authors automated detection of Darabinitol by using a conventional COBAS MIRA-S clinical chemistryanalyzer (Roche Diagnostic Systems, Inc., Montclair, New Jersey). Thissystem not only simplified the detection method but also allowed manysamples to be processed rapidly. The same instrument could also beemployed to detect serum creatinine levels which could then be used tonormalize readings to compensate for the increased levels of serumarabinitol observed during renal dysfunction.Walsh et al. (132) used the enzymatic-colorimetric method in a multi

center study of 3223 serum samples from 274 cancer patients. They foundthat among patients with candidemia, the mean maximum serum Darabinitollcreatinine ratio was 11 times greater than that of normal bloodbank donors and four times greater than that of all patient controls. Patientswith persistent candidemia had the highest D-arabinitol/creatinine levels: 25of 30 (83%) patients had elevated levels compared to 31 of 42 (74%) casesof non-persistent candidemia. Elevated ratios preceded positive bloodcultures in up to 50% of the cases. Moreover, serial D-arabinitollcreatinineratios correlated with therapeutic response in 29 of 34 (85%) patients withevaluable cases of candidemia, decreasing in eight of nine (89%) patientswith clearance of candidemia and increasing in 21 of 25 (84%) patients withpersistent candidemia (132).A recombinant form of D-arabinitol dehydrogenase from C. tropicalis

was used to improve test specificity even further (130-132) and, morerecently, a recombinant C. albicans D-arabinitol dehydrogenase has beenproduced in E. coli and purifed by dye-ligand affinity chromatography.Whereas the previous enzyme preparations metabolized host D-mannitol(although at a slower rate) as well as arabinitol, the purified C. albicansrecombinant enzyme only cross-reacts with xylitol (4.9%) among all polyolstested (133). The system using the recombinant C. albicans enzyme has beenautomated to measure the initial production rate of NADHspectrofluorometrically in a COBAS FARA II centrifugal autoanalyzer

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(Roche Diagnostic Systems); creatmme levels can be measuredsimultaneously. The assay is highly reproducible and very rapid (3.5 min perassay). For 11 patients with invasive candidiasis, the mean Darabinitol/creatinine ratio was 2.74 flM/mg/dl (range, 1.6-19.1) whereas forhealthy controls the mean ratio was 1.14 flM/mg/dl (133). The rapidity,higher throughput, and ease of use of the newer methods to detect Darabinitol in body fluids should allow for more clinical utility, particularlyfor the rapid diagnosis of severely ill patients in the ICU setting.

DIAGNOSIS OF INVASIVE ASPERGILLOSIS IN THEINTENSIVE CARE UNIT

Most infections with Aspergillus species are caused by Aspergillus!umigatus, A. jlavus and A. terreus although invasive infections caused by A.niger, A. ustus, A. versicolor and A. nidulans have occasionally beenreported. The emergence ofA. terreus, which is resistant to amphotericin B,as an agent of invasive aspergillosis has made identification of the infectingspecies important for the selection of appropriate antifungal therapy.A definitive laboratory diagnosis of invasive aspergillosis requires

isolation of the infecting organism in culture as well as histopathologicalevidence of deep tissue invasion by septate, non-pigmented hyphae whichbranch dichotomously. Only a probable diagnosis may be made on the basisof histopathologic evidence in the absence of culture because several othernon-pigmented moulds, such as Fusarium and Scedosporium species havesimilar morphologies in tissue. Newer monoclonal antibodies for thehistopathological identification ofAspergillus species are now commerciallyavailable (Dako Corp., Carpinteria, California). If extended clinicalevaluations determine that these monoclonal antibodies are specific, theymay prove to be useful for the identification ofAspergillus species in tissuesections. However, tissue biopsies would still be required which aredangerous to perform in thrombocytopenic patients.Although Aspergillus species are known to disseminate to deep tissues

via the bloodstream, blood cultures are usually negative even when lysiscentrifugation tubes are employed. Cultures of respiratory secretions areconsidered to be insensitive with organisms recovered in only 12-34% ofcases. To complicate matters, the ubiquitous nature ofAspergillus species inthe environment can make positive culture from non-sterile body sites a verynon-specific diagnostic indicator.Detection of circulating antibodies to Aspergillus species antigens has not

been particularly helpful in the diagnosis of invasive disease ingranulocytopenic patients. However, detection of antibodies may be a useful


adjunct to other methods of diagnosis in less severely immunocompromisedindividuals, such as critical-care patients. On the other hand, antigendetection tests, which do not rely on a functioning immune system, holdpromise as relatively non-invasive diagnostic tests in bothimmunocompromised and immunocompetent patients. One such assay,which has been reported to have a sensitivity of 67-100% and a specificity of81-99%, detects galactomannan, a cell wall component of A. fumigatus andA. flavus, in serum of infected patients. This test has been commercializedalthough it has not yet been approved for use in the United States. Lastly,PCR-based methods have been developed which promise to provide a rapidand specific diagnosis of invasive aspergillosis. The usefulness of each ofthese methods will be reviewed in the pages to follow.

Direct microscopy and culture

Direct microscopic visualization of the organism in body fluids, such assputum, or bronchoalveolar lavage (BAL) fluid, can be diagnosticallyhelpful although recovery from sputum is often more successful in patientswith allergic aspergillosis rather than invasive aspergillosis. Aspergillusspecies have been reported to exhibit a distinct fluorescence inPapanicolaou-stained cytology specimens which may allow a more sensitivemethod for the rapid direct identification of these organisms without theneed for culture (134). Other non-specific stains, such as the opticalbrightener, Blankophor-P-Flussig, or Calcofluor White, may also help tomake specific fungal forms more apparent in direct microscopy specimens;however, the Gram stain is not usually very helpful (135,136). The FontanaMasson stain has also been reported to non-specifically detect Aspergillusspecies in tissue sections (137).Although direct visualization of non-pigmented, septate fungal hyphae

with dichotomous branching in clinical specimens is highly suggestive ofinvasive aspergillosis, the organisms do not always display suchpathognomonic characteristics. The presence of fungal forms consistent withAspergillus species in cytology specimens was found to be neither specificnor sensitive for diagnosis of significant infection (138). Also, organismsfound in sputum or BAL fluid may only represent colonization orcontamination rather than invasive disease (139). Nonetheless, such findingsin an immunocompromised or debilitated patient should not go unheeded.Positive cultures are more convincing evidence of invasive disease ifmultiple colonies occur on the isolation plate or if the same fungus isrecovered on multiple occasions. Culture from a sterile site, such as blood ortissue, is evidence for truly invasive disease. However, tissue biopsies are

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potentially hazardous to the immunocompromised patient who is most likelyto also be thrombocytopenic.Blood cultures for Aspergillus species are usually negative, despite the

use of lysis centrifugation tubes and despite dissemination being mostcommon via the hematogenous route. Efforts to isolate Aspergillus speciesfrom other clinical specimens have yielded positive cultures in only 12-34%of cases (136). Even in patients with proven invasive pulmonaryaspergillosis, recoverable fungi were detected in only 30% and 50% ofcultured sputum and BAL fluid specimens, respectively (140-142). Recoveryof Aspergillus species from respiratory secretions is considered not only tobe relatively insensitive, but also to be non-specific due to the ubiquitousnature of the organisms (143,144). The repeated recovery of an Aspergillusspecies from the respiratory tract of a febrile immunocompromised patientwith pulmonary infiltrates, however, warrants further examination ascontinued colonization has been associated with invasive disease(142,145,146). In contrast, positive cultures from non-granulocytopenicpatients demonstrated a low predictive value for invasive disease (142).Similarly, the significance of nasal colonization is less clear although duringan outbreak of nosocomial aspergillosis, Aisner et al. found that positivenasal surveillance cultures of A. flavus in granulocytopenic patientscorrelated with invasive pulmonary aspergillosis (147). Further analyses arewarranted in non-outbreak situations. On the other hand, the absence ofpositive nasal cultures in a persistently febrile neutropenic patient with apulmonary infiltrate should not be used to exclude a diagnosis of invasiveaspergillosis. Ultimately, to avoid mis-diagnosis resulting fromcontamination or colonization, a tissue biopsy and conventionalimmunohistology may be the only methods for the specific identification ofa truly invasive infection (148,149).

Immunohistology and molecular histology

In the absence of culture from a sterile site, a definitive diagnosis ofaspergillosis is difficult to establish. In host tissue, aspergilli are visualizedby conventional staining techniques as septate, colorless hyphae of 3-12 f..l.mdiameter. The hyphae frequently exhibit dichotomous branching at 45°angles which are generally oriented in the same direction and have apropensity to invade blood vessels (150). A strong presumptive diagnosis ofaspergillosis is suggested when such features are observed in tissue becauseother fungi which often resemble aspergilli in tissue, such as Fusarium andScedosporium species, possess hyphae which are somewhat narrower andwhich branch at less acute angles. However, the similar clinical features andhistopathology of Fusarium and Scedosporium infections, along with the


morphological similarity of these organisms and their propensity to alsoinvade blood vessels, makes conventional histological differentiation ofthese fungi difficult when pan-fungal stains, such as periodic acid-Schiff orGrocott methenamine silver stain, are used (150). Differentiation ofaspergillosis from Scedosporium infections, as well as differentiation ofinfections caused by A. terreus from those caused by other Aspergillusspecies may be critical because Scedosporium and A. terreus infections maybe resistant to amphotericin B therapy (151). Therefore, specificimmunohistochemical stains, which could differentiate between genera oreven species, would be of great diagnostic value.Unfortunately, because many fungi share similar antigenic epitopes, most

antisera raised against specific fungi for use in immunohistology cross-reactwith more than one genus of fungus. Often these reagents, particularly ifthey are derived from polyclonal antibodies, must be adsorbed out withwhole organisms to remove the cross-reactive elements (152-154). Althoughthese reagents then become more specific, they often become less sensitiveand give only weak positive reactions against the organism of interest(74,150,154). Instead of using polyclonal antibodies, Arrese-Estrada et al.(155) developed a monoclonal antibody (EB-Al), directed against the fungalcell wall component, galactomannan, which could differentiate Aspergillusfrom Fusarium species by immunoperoxidase staining. However, eventhough monoclonal antibodies were employed, cross-reactivity was detectedamong morphologically divergent fungi.A new reagent for the immunohistological identification, but not

differentiation, of A. fumigatus, A. flavus, and A. niger is now availablecommercially (Dako Corp.). This reagent is a monoclonal antibody whichspecifically reacts with only these three species of Aspergillus. Originallydescribed by Jensen et al. (156), two monoclonal antibodies, WF-AF-l andWF-AF-2, raised against the cell wall fraction of A. fumigatus, were testedagainst tissues from mice infected with a variety of agents. WF-AF-l wasthe only monoclonal antibody which gave 3+ staining of only A. fumigatus,A. flavus, and A. niger and of no other organism tested. AlthoughPenicillium marneffei was not tested, the authors speculated that crossreactions would occur with this organism because the reactivity ofWF-AF-lwas most likely against the galactomannan component of the Aspergilluscell wall and the galactomannan of P. marneffei is antigenically similar, ifnot identical, to that of Aspergillus species. Nonetheless, the authorssuggested that in tissue P. marneffei would occur as a yeast form in contrastto Aspergillus species, which appear as hyphae. Therefore, in the absence ofrare, structurally elongated P. marneffei forms in tissues, this new reagent

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should be very beneficial if proven to be as sensitive and specific asreported.Recent advances in the use ofmolecular histology or in situ hybridization

(ISH) using specific DNA or RNA probes to identify fungi in paraffinembedded tissue sections or cytology specimens have been reported (157159). Zimmerman et al. (157) described the use of an Aspergillus-specificrRNA probe to detect fungal forms in cytology cytospin and thin-preparationspecimens using ISH. Four patients were initially diagnosed with pulmonaryaspergillosis by cytological examination and A. fumigatus infection was laterconfirmed in three of the four cases by culture. Each of the cytologyspecimens from all four patients were positive by ISH and most, but not all,of the fungal elements were stained with the probe. ISH took only one hourto complete when cytology specimens were used.

Antibody detection in the diagnosis of aspergillosis

Although ill and counterimmunoelectrophoresis (CIE) have proved valuablefor the diagnosis of aspergilloma and allergic bronchopulmonaryaspergillosis in immunocompetent individuals, the contribution of specificantibody detection tests to the diagnosis of invasive aspergillosis inimmunosuppressed patients, who either lack a sufficient antibody responseor who mount variable antibody responses, remains controversial (160-164).There appears, however, to be agreement among several studies thatseroconversion can be successfully used to monitor disease when serialserum samples are tested. In addition, an increase in antibody titer at the endof immunosuppression indicates a good prognosis whereas absent ordeclining antibodies suggest a poor outcome (165,166). For example, in astudy of lung transplant recipients with A. fumigatus infections, increasingspecific IgG antibody levels corresponded with lung function impairmentand with cytological and microbiological recovery of the organism; recoveryof lung function correlated with a decrease in antibody titer (167,168).Therefore, antibody detection in immunocompromised hosts may be used fordetermining a prognosis if not a diagnosis.

Antigen detection in the diagnosis of aspergillosis

The predictive value of antibody detection for the diagnosis of aspergillosishas been so variable that much research has been devoted instead to thedetection of Aspergillus species antigens in serum and urine. Of thecarbohydrate antigens, galactomannan (GM), a major cell wall component ofAspergillus species, has received the most attention. Initial studies used CIEto detect GM in the serum and urine of patients and rabbits experimentally


infected with A. fumigatus (169). This was followed by the development ofincreasingly more sensitive and more rapid RIA (170-172), LA (173,174)and ElA (175-178) formats. Two tests to detect circulating GM arecommercially available in some countries and utilize an anti-GMmonoclonal antibody, EB-A2, in either an LA or sandwich ElA format(174,178-180). The LA test was the first to be developed (PastorexAspergillus, Sanofi Diagnostics Pasteur) (174,175,181) but, despite its easeof use, lacks sufficient sensitivity.More recently, a sandwich ElA format to detect circulating GM, using

the same monoclonal antibody, EB-A2, was developed (Platelia Aspergillus,Sanofi Diagnostics Pasteur) (178,180). This assay appears to be moresensitive than the LA (the ElA can detect one ng ofGM per ml in contrast tothe LA which can only detect 15 ng per ml) and can detect GM in serum atan earlier stage of infection than the LA (178,182,183), before clinical signsand symptoms become apparent (184,185). A higher test sensitivity wasfound using serum than urine (60 of 419 or 14% versus 18 of 373 or 5%),even though concentration of the urine lO-fold before testing increased thenumber of positive samples to 31 of 373 or 8% (186). Disappearance of theantigen during antifungal therapy correlated with good outcome whereaspersistence of the antigen correlated with poor clinical outcome (186).Although the use of urine specimens resulted in lower sensitivity (186) andspecificity (175) than serum, detection of GM in BAL fluid from patientswith invasive aspergillosis correlated with serum positivity (187). In aretrospective study, Caillot et al. found the sandwich ElA to be positivewhen BAL was tested for 83% of 23 histologically proven and 14 highlyprobable cases of invasive aspergillosis in granulocytopenic patients (188).Maertens et al. (189) evaluated the diagnostic usefulness of the sandwich

ElA in a prospective study of 186 consecutive hematology patients atincreased risk of invasive aspergillosis. A total of 2, 172 serum samples from243 episodes were tested and of 71 patients with culture- and histologyconfirmed invasive aspergillosis, the sensitivity and specificity of serial GMmonitoring were 92.6 and 95.4%, respectively. False-positive reactionsoccurred at a rate of 8%, although the strict criteria used for confirmedinvasive aspergillosis may have overestimated this number. In addition, thecut-off value for positivity used by this group was lower than thatrecommended by the manufacturer (an OD index of 1.0 rather than 1.5 wasused) which may also have contributed to the high false-positive rate(189,190). Nonetheless, in more than half of the cases, antigenemia wasdetected before clinical suspicion of invasive aspergillosis (median antigenpositivity, 6 days before clinical suspicion).

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Thus far, most prospective studies of the utility of the sandwich EIA havebeen conducted using hematological patients. One recent study, however,examined the utility of the sandwich EIA in liver transplant recipients (191).In a retrospective case-control study, 14 cases of invasive aspergillosis werediagnosed in 240 liver transplant patients over a period of 5 years. Thesensitivity and specificity of the sandwich EIA in this patient populationwere 55.6 and 93.9%, respectively, indicating that this test may be moresuitable for hematological patients than for transplant recipients.A series of immunoreactive proteins have been associated with somatic

and cell wall components of Aspergillus species (192-196). These include,but are not limited, to 58 kDa (193), 88 kDa (192), and 18 kDa (197)proteins, an alkaline protease (195), a serine protease (196), a superoxidedismutase (198,199), and a catalase (200). Whereas patient antiserum hasbeen shown to react with these compounds in immunoblots, the number oftests developed to detect antigens, rather than reactive antibodies, in theurine or serum ofpatients with invasive aspergillosis has been more limited.The protein moiety receiving the most attention has been an 18 kDa

protein (197) which has sequence homology with a ribonucleotoxin orrestrictocin ofA.fumigatus (201-204). The 18 kDa protein is a specific RNAnuclease which cleaves a phosphodiester bond in a conserved region of thelarge ribosomal subunit of RNA releasing a 400 bp fragment from the 3' end(203). Urine from 10 bone marrow transplant patients contained severalprotein antigens of low molecular weight (11-44 kDa in size) when reactedwith rabbit polyclonal antiserum directed against a cell wall extract from A.fumigatus (197). These antigens were distinct from GM in that an anti-GMmonoclonal antibody (EBAl) reacted diffusely to bands greater than 45 kDaonly (197). Urine specimens from 23 patients with no evidence of invasiveaspergillosis did not react with either the polyclonal or monoclonalantibodies (197). Circulating proteins have also been reported to occur in theserum and urine of rats, where an 80 kDa antigen was detected (205).Unfortunately, the 80 kDa antigen was not found in the serum of threehuman cases of aspergillosis. Others (206) used a rat model of experimentalaspergillosis and examined urine from infected animals for Aspergillusantigens by immunoblotting. Antigenic bands were detected at 20, 27, 40,and 88 kDa. Burnie and Matthews (207) determined that the 88 kDa bandcould be detected using a monoclonal antibody directed against the HSP-90protein of C. albicans. It was hypothesized that there may be an Aspergillusantigen, analogous to the HSP-90 of C. albicans, circulating in invasiveaspergillosis. Chumpitazi et al. (208) described an inhibition EIA whichcould detect three predominant antigens of A. fumigatus (18, 33, and 56kDa). Circulating antigen was found in five of seven cases of proveninvasive aspergillosis and in two of the five cases, antigenemia was detected


before positive radiologic signs. No antigens were detected in sera frompatients with proven invasive aspergillosis caused by A. flavus or A. terreusor in control sera. The inhibition EIA was significantly more sensitive thanthe galactomannan LA assay in that only one patient with probable invasiveaspergillosis had a positive result by the LA test. The overall sensitivity andspecificity of the inhibition EIA were 71.4 and 94.4%, respectively. Otherprotein antigens as well as those described here have recently beenextensively reviewed elsewhere (209). In addition, although the goal of thework by Weig et al. (210) was to use the recombinant 18 kDa antigen(mitogillin) to detect antibodies to this immunodominant protein, they alsodemonstrated that rabbits could be immunized with the recombinantmolecule to produce relatively specific anti-mitogillin antibodies. It wouldbe of interest to determine if the anti-mitogillin antibodies produced by theseauthors could be used to detect circulating mitogillin in the serum or urine ofaspergillosis patients.

MOLECULAR BIOLOGICAL METHODS FOR THEDIAGNOSIS OF CANDIDIASIS AND ASPERGILLOSIS

The detection of fungal DNA directly from clinical specimens offers severaladvantages over conventional diagnostic tests. First, fungal DNA present inclinical materials can be amplified a million-fold or more using PCR-basedmethodology. In addition, DNA derived from dead as well as from livingfungal cells can be amplified in this system. Therefore, for both of thesereasons, a PCR-based assay should be more sensitive than culture. Inaddition, it should also be more rapid than either culture or antibodydetection assays. Use of specific oligonucleotide probes can provideidentification of an organism to the species level directly from clinicalmaterials and can theoretically detect mixed fungal infections. Finally, newerreal-time PCR assays such as the TaqMan system (Perkin Elmer AppliedBiosystems, Inc., Foster City, California) and the Light Cycler system(Roche Molecular Biochemicals, Inc., Indianapolis, Indiana) require no postamplification manipulations and can potentially be automated for all stepsfrom DNA extraction to final PCR amplicon detection and quantitation.There are perhaps as many different targets for PCR amplification as

there are researchers conducting such tests. Several groups have used singleor low copy gene targets for amplification which are very specific for aparticular species or genera (211-226). Examples of such targets includegenes for lanosterol 14a-demethylase (211,217-220), actin (217,218), HSP90 (215), aspartic proteinase (221), aspergillopepsin (222), alkaline protease

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(223), an 18 kDa immunoglobulin E binding protein or ribotoxin (224), andchitin synthetase (216,225), or multi-copy mitochondrial DNA (226).A more widespread approach has been to use universal or pan-fungal

DNA gene targets and high copy number genes to increase test sensitivityand broaden applicability (227-258). The highly conserved regions ofribosomal DNA have been the most popular targets and have included the5.8S (227), 18S (228,230,232,237-247), and 28S (231,248-251) rRNA genesas well as primers which amplify across the more highly variable internaltranscribed spacer (ITS) regions between these genes (233-236,252-258).The main advantage of using amplification targets from regions of DNA

which are conserved among all fungi, but which are not present in viruses,bacteria, or mammals, is that a PCR product can be obtained from all fungiusing a single set of PCR primers under conditions optimal for that single setof primers. Following amplification, species- or genus-specific probes thathybridize to only one or a few targets can then be designed from morevariable regions contained between primer binding sites for the identificationof specific organisms. Using pan-fungal primers and oligonucleotide probes,Einsele et al. (232) reported a detection limit of 1-10 fg of fungal DNA (1cfu per ml of blood) using this method and a sensitivity of 100% for patientswith documented invasive infections when two or more blood samples weretested. Positive PCR preceded radiological signs by a median of 4 days for12 of 17 patients with hepatosplenic candidiasis or pulmonary aspergillosis.This method could also be used to monitor response to antifungal therapy inpatients with invasive aspergillosis as the number of PCR-positive samplesdeclined in patients responding to therapy in contrast to those who did notrespond (232). Using this approach, but taking it one step further, Shin et al.(234) used universal PCR primers to amplify DNA from Candida speciesgrown in blood culture bottles. A natural amplification of target DNAoccurred as yeasts were allowed to grow in blood culture bottles so that avery rapid mechanical disruption method, which did not require expensiveenzymes or phenol-chloroform extraction, could be used. The limit ofdetection was 500 cfu per ml which, although high, was sufficient to detect100% of the positive cultures.The earliest method for the detection of PCR products was gel

electrophoresis, either with or without the use of restriction enzymedigestion, followed by ethidium bromide staining (211,213,215,219,222,229,240,258-260). Increased sensitivity was then achieved by adding Southernblotting of the gels onto nylon membranes and detection with radio-labeledprobes (212,215,216,224,227,230,238,243,245,261). Others have used lineprobe, reverse cross blot, slot blot, and direct fluorescent capillary automatedDNA sequencing assays (220,231,243,256) or single strand conformationalpolymorphism to detect PCR products (251,254).


The application of an enzyme immunoassay (EIA) fonnat, using eithercolorimetric or fluorometric dyes, is perhaps the easiest and least costlymethod available for amplicon detection (221,233-236,240,252,253,263,264). This fonnat is highly user-friendly and does not require any dangerousor costly radioactive probes and yet has equal sensitivity to Southern blottingmethods (264).Most recently, detection methods have been developed which are referred

to as real-time PCR because detection of the amplicon occurs as the PCRproduct is produced and quantitative results can be graphically displayedduring this process. Therefore, no post-amplification manipulations of theproduct are required. The TaqMan system (Perkin-Elmer AppliedBiosystems, Inc.) is a fluorogenic assay which uses a reporter and aquencher dye in proximity to each other on the detector probe. As DNAamplification occurs, the 5'-3' endonuclease activity of the Taq DNApolymerase separates the quencher dye from the reporter dye allowing signalto be detected. This system was used by Shin et al. (235) to identify Candidaspecies from 61 blood culture bottles. Universal fungal primers were used toamplify the internal transcribed spacer region 2 (ITS2) of all Candidaspecies and species-specific probes to this region were labeled with one ofthree fluorescent reporter dyes. Each dye emitted a characteristic wavelengthallowing up to three Candida species to be detected in a single reaction tube.Probes correctly detected and identified 58 (95.1%) of 61 DNAs recoveredfrom blood culture bottles, including those culture positive for C. albicans,C. parapsilosis, C. glabrata, C. krusei, and C. tropicalis. No false positiveresults were obtained from bottles with no growth or from patients withbacteremias. This assay could detect and identify Candida to the specieslevel in less than one day. Similar results were obtained by Guiver et al.(265) using the TaqMan system and probes to identify C. albicans, C. kefyr,C. parapsilosis, C. krusei, and C. glabrata.The TaqMan system has also been used to identify A. fumigatus in pure

cultures and in clinical specimens (266,267). Brandt et al. (266) used arandomly amplified polymorphic DNA (RAPD) method and PCR to identifysection- or species-specific amplicons among seven medically importantAspergillus species. A primer pair specific for A. fumigatus was designedwhich generated an 864-bp PCR product. This product could be detected bythe TaqMan system in 89 of 90 A. fumigatus isolates tested. Costa et al.(267) used a mitochondrial gene target and the TaqMan system to amplifyand detect A. fumigatus DNA spiked into whole blood and compared serum,plasma, and the white cell pellet as specimens for optimum DNA recovery.It was detennined that whereas serum and the white blood cell pellet werecomparable for the recovery of A. fumigatus DNA, the yield from plasma

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was 10 times lower. It was also determined that serum should be frozen assoon as possible after collection to prevent degradation of the DNA.The other real time PCR system is the LightCycler (Roche Molecular

Biochemicals, Inc.) which allows rapid amplification of DNA in glasscapillaries and simultaneous fluorescent detection of amplicons usingfluorescence energy transfer or FRET (246,247). One DNA probe is labeledat the 3' end with fluorescein and another probe, which binds adjacent to thefirst, is labeled at the 5' end with Light Cycler Red 640 fluorophore. Thefluorescein is excited by the light source of the Light Cycler instument andthe energy emitted by the fluorecein is transferred to the Light Cycler Red640 flurophore. The light emitted by the fluorophore is then measured and isproportional to the amount of DNA amplified. The sensitivity of the assay todetect both C. albicans and A. fumigatus was comparable to that previouslypublished by the same authors (5 colony forming units [cfu] per ml of wholeblood) and was comparable to that obtained using the PCR-EIA for detectionof the PCR amplicons. Addition of a commercial DNA extraction system(MagNA Pure, Roche Molecular Biochemicals, Inc.), applied after lysis andremoval of erythrocytes and disruption of C. albicans cells with glass beads,allowed a limit of sensitivity of 1 cfu per ml ofwhole blood (246).Selection of the appropriate clinical specimen for PCR analysis is critical

to the results obtained. No matter what specimen is chosen, extreme caremust be taken to avoid environmental contamination of the samples. This isof particular concern when detecting DNA from Aspergillus species as theseorganisms are ubiquitous in the environment and for Candida species whichare normal colonizers of the skin and mucosa. Therefore, not only is bloodconsiderably easier to obtain than BAL fluid, blood is from a sterile site. Apositive PCR result from sputum or BAL, although suggestive of infectionas detailed in previous sections of this chapter, may represent colonizationrather than true infection. Indeed, up to 25% of BAL samples from healthyadults are positive by PCR (268). Unlike BAL samples, repeated bloodsamples can be obtained to evaluate the usefulness of PCR to follow diseaseprogression and monitor drug therapy. In addition, PCR results using BALwere not congruent with the commercial antigen detection test results in onestudy (238) and the number of false-positive samples obtained was higherfor PCR than for the commercial antigen detection test (226,238).

DETECTION OF (1-3)-~-D-GLUCANFOR THEDIAGNOSIS OF CANDIDIASIS AND ASPERGILLOSIS

The cell walls of fungi, with the exception of the Zygomycetes, contain (13)-13-D-glucan (BDG) as a structural component. This polysaccharide is not


found in bacteria, viruses, or mammals and, therefore, its presence in thecirculation of patients at high risk of fungal infection has been used as anindicator of invasive disease. An assay to detect BDG has been developedwhich utilizes the activation of a clotting cascade found in amoebocytelysates of the Japanese horseshoe crab, Tachypleus tridentalis. This clottingcascade can be initiated along one of two pathways: one is activated bybacterial endotoxin and the other by fungal cell wall components. Differentactivating factors can be removed from the system to make the reactionspecific for either pathway. Removal of Factor G from the lysate permitsactivation only by endotoxin whereas removal of factors Band C permitactivation only by BDG.A test to directly measure plasma BDG was developed using isolated

Factor G, the horseshoe crab coagulation factor that is highly sensitive toactivation by BDG (269). The G test, as it has been called, is commerciallyavailable from the Seikagaku Corporation (Tokyo, Japan). The BDGdetection kit contains reagents consisting of lyophilized horseshoe crabcoagulation Factor G, proclotting enzyme, and the chromogenic substrate, tbutyloxycarbonyl-Leu-Gly-Arg-p-nitroanilide. This substrate is cleaved bythe last step in the proteolytic cascade and can be detected colorimetrically(269,270). Patient plasma, derived from heparinized blood, must first betreated with perchloric acid to precipitate interfering factors beforeapplication of the kit reagents (270).Obayashi et al. (270), in a multi-center study conducted in Japan, used

this method to measure the plasma concentration of BDG at the time ofroutine blood culture performed for 202 febrile episodes. Forty-one febrileepisodes were attributed to infections by species of Candida, Aspergillus,Cryptococcus and Trichosporon. An additional 59 episodes were attributedto infections of non-fungal etiology (i.e. Gram-negative or Gram-positivebacterial infections or febrile responses due to drug therapy) and 102 were ofunknown origin. Normal plasma concentrations of BDG never exceeded 10pg/ml and fungal febrile episodes could be differentiated from non-fungalepisodes using a cut-off value of 20 pgiml. Using this cut-off value, 37 of 41(90%) episodes associated with culture or autopsy-confirmed fungalinfection were positive. Fifty-nine episodes associated with non-fungalinfection all had BDG levels below 20 pg/ml. Of 102 episodes of fever ofunknown origin, 26 (25.5%) demonstrated elevated BDG levels. If the 102episodes of fever of unknown origin were taken to be non-fungal in etiology,the test had a positive predictive value of 59% and a negative predictivevalue of 97% (270). The highest BDG levels were observed in patients withproven deep mycoses or fungemia. On the other hand, it was speculated thatthe 102 patients with fever of unknown origin who had elevated BDG levels

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may, in fact, have had occult deep mycoses. Therefore 45 patients withneutropenia and fever unresponsive to antibacterial antibiotics were analyzedto determine responsiveness to antifungal therapy. Plasma BDG levels were~10 pg/ml in 22 of the 45 patients (49%) and were below 10 pg/ml in 23(51%). The efficacy of intravenous fluconazole or miconazole therapy wassignificantly greater in the high BDG group (81.8%) as compared with thelow BDG group (43.5%) as measured by resolution of fever after 2 weeks oftherapy. Obayashi et al. (270) proposed that these data indicate that BDGlevels may also be helpful in the discrimination of fungal from non-fungalfevers of unknown origin.Several recent studies have compared the diagnostic usefulness of BDG

detection tests to those detecting antigens or DNA from C. albicans (271273) or to those detecting antigens or DNA from A. fumigatus (273-275) orto the use of computed tomography (CT) (276). For example, Sakai et al.(271) used serum from 30 critically-ill ICU patients to compare the clinicalusefulness of a PCR assay amplifying the 18S ribosomal RNA gene of fungito that of BDG detection and to that of the Cand-Tec test for the diagnosis offungal infection. These patients had received prolonged care with parenteralnutrition and endotracheal intubation and were suspected of having a deepfungal infection. Among 24 samples in which the PCR assay, the BDG test,and the Cand-Tec test were performed in parallel, 18 (75%) were positive bythe PCR assay whereas only 13 (54%) were positive by the BDG test andfive (21%) by the Cand-Tec test. No fungal DNA was amplified from theserum of 20 healthy individuals. Because the PCR test was more sensitive,Sakai et al. (271) concluded that the PCR test was more useful than eitherthe BDG or Cand-Tec tests for the diagnosis of deep mycoses. However,these authors did not use confirmed cases of invasive candidiasis for theirstudy and used serum for testing BDG levels rather than the more commonlyused plasma. Although in unpublished observations it has been indicated thatserum may be equally substituted for plasma in the BDG test (269), it wouldbe of interest to determine if the use of serum may have reduced testsensitivity in this case.

In a recent large study (276), the BDG and Pastorex Aspergillus LA testswere compared to CT scanning for the rapid diagnosis of invasiveaspergillosis. Blood samples, taken weekly from 215 consecutive patientsundergoing cytotoxic chemotherapy, were tested by both the BDG and theLA test. Using specimens from 16 definite and 14 suspected cases ofinvasive aspergillosis, the sensitivites of the BDG and LA tests were 63%and 44%, respectively, and the specificities were 74% and 93%,respectively. All ofthe invasive aspergillosis patients had abnormal signs onchest CT scan and seven of 16 (46.5%) had either a halo or air-crescent sign.CT signs preceded a positive BDG and LA test by an average of 11.5 and 7.1


days, respectively. It was concluded that chest CT scan may be morebeneficial than either blood test for the rapid diagnosis of invasiveaspergillosis.Finally, another group compared the efficiency of the BDG and LA tests

with that of a nested PCR assay for the detection of invasive aspergillosis inan experimental rat model (275). These authors found that by day 2 postinfection, both the BDG and PCR-based assays gave positive results for 80%of samples whereas the LA gave positive results in only 60% of samples. Byday 3 post-infection, the PCR assay had surpassed both of the other tests(i.e., 87.5% positive by PCR and 75% and 71.4% positive by BDG and LA,respectively) although elevated levels of BDG did parallel the developmentand progression of invasive disease.

In general, for the diagnosis of invasive candidiasis or aspergillosis, thesestudies suggest that the most sensitive assay will be the PCR assay and thatboth PCR and CT will give a more rapid and accurate diagnosis of specificfungal infection than the BDG, Cand-Tec, Pastorex Candida, or PastorexAspergillus LA tests. However, all of the PCR tests are in-house assayswhich are not readily available for use by other laboratories whereas all ofthe other tests are available commercially in a number of countries, althoughnot in the United States. In addition, although the BDG tests were superior tothe LA tests, the newer, improved sandwich EIA test, with greater sensitivityfor detect circulating galactomannan described earlier in this chapter(175,178), is now commercially available for diagnostic use in somecountries and should soon be available in the United States. Therefore, futurecomparisons should include this improved test.Although the BDG test cannot identify which fungus is specifically

causing an infection, results can be obtained within 2 hours. Such rapiditymakes it very attractive as a screening test for invasive infection by commonas well as less common fungi, including those for which no other serologicaltest is available (277). Automation of this assay will make it more attractivefor evaluation in prospective studies and for use in the clinical laboratory(278). However, the test has not been shown to be useful for the detection ofpulmonary cryptococcosis in otherwise healthy individuals and this defecthas been speculated to occur as a result of a slower growth rate and thickcapsule formation in immunocompetent hosts (270). Alternatively, thesenegative results may be caused by the reduced amount of BDG found in thecell wall of Cr. neoformans (270). Other potential problems with accurateBDG detection occur in patients receiving hemodialysis with cellulosicmembranes, such as cuprammonium rayon, which contain polysaccharidesthat are shed into the bloodstream during dialysis (269). Also, patientsreceiving parenteral infusions of plasma components, such as g-globulin,

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which is filtered through cellulose membranes during manufacture, can givefalse positive results (269). Keeping such factors in mind, it will mostprobably require the application of several diagnostic tests in parallel inorder to obtain the most sensitive and specific diagnosis of invasive fungalinfections.

DIAGNOSIS OF LESS COMMON INVASIVE FUNGALINFECTIONS IN THE INTENSIVE CARE UNIT

Although Candida and Aspergillus species are by far the most commoncause of fungal infections encountered in the ICU patient, there are nowmore frequent reports of serious illnesses caused by Trichosporon asahii(formerly T beigelii) , Malassezia and Fusarium species, and by theZygomycetes. The patients most susceptible to these infections are severelydebilitated and many of the causal agents are resistant to antifungal therapyleading to a poor clinical outcome. Therefore, a rapid and accurate diagnosisis essential for institution of appropriate drug therapy. Unfortunately,immunoserology has little to offer for the diagnosis of most of theseinfections and few molecular biological methods have been reported to date.Culture can be helpful in some cases; for example, T asahii can be culturedfrom blood, urine or cutaneous lesions. Monoclonal antibodies have beenproduced for the detection of T asahii in tissues (279,280), but no reliableserological tests are available for the diagnosis of trichosporonosis. T asahiidoes, however, share a heat-stable antigenic determinant with the capsularantigen of C. neoformans and serum from trichosporonosis patients maycross-react in the Cryptococcus LA antigen test (74,281-283). A negativeCryptococcus antigen test does not, however, exclude disseminatedtrichosporonosis (283).

Malassezia species infections occur most often in low-birth-weightinfants, or in debilitated adults or children who are receiving total parenteralnutrition via central venous catheters. Nutritional solutions containing lipids,or catheters supplying these solutions, become contaminated and provide asource for the replication of the organism (284). Malassezia furfur and M.pachydermatis are lipophilic organisms which are difficult to recover fromperipheral blood although contaminated catheter tips may yield viableorganisms. Subculture requires inclusion of lipid in the growth medium oroverlayering of agar with lipid and incubation for 4 to 6 days at 32°C.Infections by Fusarium species may be caused by at least 12 different

species although the most common are F. solani, F. moniliforme, and F.oxysporum. These infections are accompanied by a high mortality rate andare difficult to treat with currently available antifungal agents (285). Many


isolates of Fusarium species are refractory to therapy with amphotericin B,fluconazole, and itraconazole (286-289). Clinical symptoms resemble thosefor aspergillosis and, in tissue, Fusarium species are often mistaken forAspergillus species. Both organisms have a predilection for vascularinvasion and cause thrombosis and tissue necrosis. Unlike Aspergillusspecies, however, Fusarium species can be more easily cultured from bloodand can be recovered from approximately 60% of cases.Zygomycotic infections can be divided into agents belonging to the

Mucorales, which are more likely to cause invasive or disseminatedinfections, and the Entomophthorales, which cause primarily subcutaneousinfections. Primary agents of zygomycosis of the Order Mucorales includespecies of Absidia, Apophysomyces, Cunninghamella, Mucor, Rhizopus,Rhizomucor, and Saksenaea. In tissue, these organisms appear as irregularlybranched, sparsely septate, broad (10-20 Ilm), ribbon-like hyphae.Rhinocerebral zygomycosis involving the palate, nasal mucosa and sinuses,and the orbit may occur and can invade into the brain resulting in a fatalinfection. Pulmonary, cutaneous, and gastrointestinal zygomycosis may alsooccur and any of these forms, as well as the rhinocerebral form, maydisseminate via vascular invasion to the lungs, liver, spleen, kidneys, andgastrointestinal tract.Although early diagnosis of this rapidly progressive disease is desirable,

more than 90% of disseminated cases of zygomycosis are diagnosed atautopsy (74). A combination of tissue morphology and detection ofzygomycotic antibodies by EIA allowed successful diagnosis of a fatal caseof rhinocerebral infection caused by Saksenaea vasiformis (290). Antibodiescould be detected early during infection, one month before isolation andthree months before identification of the organism. CSF titers against S.vasiformis were diagnostic for infection and increased during clinicaldeterioration (291). In this study, antigens were derived from Rhizopusarrhizus and S. vasiformis.Antibodies to R. arrhizus have been detected in the sera of patients with

cerebral infections caused by this organism (291,292). In addition,antibodies to Absidia corymbifera were found in the CSF and serum of apatient with culture-proven Absidia meningitis (293) and in the serum of apatient with a histologically proven Absidia brain abscess (291).The common peptido-L-fuco-D-mannan found on the cell surface of

species of Rhizomucor, Absidia, and Rhizopus results in cross-reactivityamong the major antigens of these organisms (74,294). Homogenizedantigens from A. corymbifera, Rhizomucor pusillus, and R. arrhizusdemonstrated a sensitivity of 70% and a specificity of 90% in an ill test forthese zygomycetes (74,295). Patients generate antibodies to the

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Zygomycetes during infection whereas normal healthy volunteers andpatients with other infections produce very low amounts of antibodies tothese agents. An EIA format that was 81% sensitive and 94% specific forZygomycetes was also developed where a 1:400 antigen titer was consideredto be a positive result (74,290). Additional evaluations of the ill and EIAtests for the diagnosis of zygomycosis are needed to determine their trueclinical utility.

CONCLUSION

The number and variety of organisms causing opportunistic infections israpidly increasing. Because the host's capacity to mount an immuneresponse is debilitated in patients susceptible to opportunistic infections and,as a result, the disease course is often fulminant and rapidly fatal, serologicaltests which rely on a functioning immune system (i.e. antibody detectiontests) are of limited value. Therefore, antigen detection tests, which can beused in the absence of a functioning immune system, have gained favor.Nonetheless, invasive opportunistic infections can occasionally occur in lessseverely immunocompromised patients resulting in a more prolonged,localized disease progression. In these cases, antibody detection cansometimes be useful. Therefore, antigen and antibody detection tests for thediagnosis of opportunistic fungal infections may each have utility dependingupon the patient population under examination. In addition, pan-fungalantigen detection tests, such as the BDG test, and universal PCR assays,particularly when standardized and automated, could complement existingtests for the diagnosis of invasive fungal infections encountered in the ICU.

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245. Becker MJ, De Marie S, Willemse D, Verbrugh HA, Bakker-Woudenberg, IAJM.Quantitative galactomannan detection is superior to PCR in diagnosing and monitoringinvasive pulmonary aspergillosis in an experimental rat model. J Clin Microbiol2000;38: 1434-38.

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255. Turenne CY, Sanche SE, Hoban DI, Karlowsky lA, Kabani AM. Rapid identification offungi by using the ITS2 genetic region and an automated fluorescent capillaryelectrophoresis system. I Clin Microbiol 1999;37: 1846-51.

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Chapter 6

Clinical Diagnosis of Fungal Infection in the IntensiveCare UnitEuropean Perspective

PAUL G. FLANAGANUniversity ofWales College ofMedicine, Cardiff, United Kingdom

The incidence of fungal infections in the intensive care unit (lCU) hasincreased significantly in the last 20 years, primarily as a result of theexpansion of invasive monitoring, transplant surgery and cancerchemotherapy (1-3). Invasive mycoses are particularly problematic in theICU as they are difficult to diagnose and there is a limited range ofantifungal agents available. Candida species are by far the most commoncause of fungal infections in the ICU, constituting about 90-95% of thereported cases (4-6). The remainder are caused by a variety of fungiincluding Aspergillus species and other yeasts such as Malassezia furfur andRhodotorula species (7-9).

CLINICAL DIAGNOSIS OF CANDIDIASIS IN THEINTENSIVE CARE UNIT

Data from the National Nosocomial Infections Surveillance (NNIS) systemdemonstrated a five-fold rise in the rate of Candida bloodstream infectionsbetween 1980 and 1990 (1). Candida albicans is still the most commonlyisolated species causing candidiasis among critically-ill patients (about 60%of all infections) (2,5-6). The proportion of ICU cases of candidiasis causedby non-albicans species of Candida, such as. C. glabrata, C. parapsilosis,and C. tropicalis, has also increased significantly in the last decade (2).Candidiasis is most likely to occur in immunosuppressed patients with anunderlying malignancy or hematological disorder and among post-surgicaland neonatal ICU patients (2,10-12). The clinical diagnosis of candidiasis in

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the ICU remains a challenge because of the varied clinical presentations andnon-specific signs in these patients (11,13-17). The diagnosis of candidiasisoften remains a clinical decision, based on the available supporting evidencein an individual patient. The clinician must maintain a high index ofsuspicion in a high-risk patient, as it is not possible clinically to distinguishcandidiasis from other causes of deep-seated sepsis.

Definitions

The term invasive candidiasis indicates that Candida species have gainedaccess to normally sterile sites. It includes a spectrum of diseases that can beclassified according to the relative degree to which candidemia and focalorgan involvement dominate the clinical picture (18). It has been classifiedinto: candidemia, acute disseminated candidiasis, chronic disseminatedcandidiasis and deep organ candidiasis (19). Candidemia is defined as thepresence of one or more positive blood cultures for Candida species (19). Itmay lead to deep organ candidiasis and vice versa. Acute disseminatedcandidiasis describes the formation of microabscesses in multiple noncontiguous organs, secondary to hematogenous spread (13,15,19,20). Thesource of the infection mayor may not be an indwelling central venouscatheter. Chronic disseminated candidiasis (formerly known ashepatosplenic candidiasis) is seen after resolution of prolonged severeneutropenia (20). Some patients with chronic disseminated candidiasis mayrequire intensive care.

CLINICAL DIAGNOSIS OF CANDIDEMIA

Candidemia has a significant effect on length of hospitalization andmortality (4,21). An indwelling intravascular catheter is the most commonsource of candidemia in the ICU (4-6,22,23), although a significantproportion of cases are thought to arise from translocation of yeasts acrossthe bowel wall (13,24). Patients frequently have several risk factors forinvasive candidiasis, e.g. intravascular catheters, prolonged mechanicalventilation (>7 days), documented fungal colonization from several noncontiguous non-blood body sites, prior exposure to multiple broad-spectrumantibiotics (22,25,26). The mean interval between ICU admission and thediagnosis of candidemia has been reported as 14-30 days (4,5,23). Adultswith candidemia usually present with persistent fever despite broadspectrum antibiotics, but with few other symptoms and signs (10,11,14).Endophthalmitis is present in up to 45% of cases (27-29). Othermanifestations of candidemia, such as suppurative thrombophlebitis (30) and

6. Clinical Diagnosis ofFunga/ Infection in the Intensive Care Unit 107

macronodular erythematous skin lesions are rare in the ICU (31,32).Occasionally candidemic patients present with septic shock, which has agrave prognosis (13). Conversely candidemia can produce minimalsymptoms and the isolation of Candida species from blood cultures may bethe only clinical evidence of invasive candidiasis (13,16). It was this subsetof patients who gave rise to the term 'benign transient candidemia', who itwas thought, did not require antifungal therapy (33-35). This has now beenshown to be a hazardous interpretation, given the high incidence ofmetastatic complications (23) and excess mortality in untreated candidemia(10,11,16). Waiting for a second positive blood culture to confirm thesignificance of the first, is also clinically untenable (36). The incidence ofcontamination of blood cultures with Candida species is unknown, but wasreported to be as high as 12% in one series (37). Berenguer et a/.demonstrated that there is a direct relationship between the tissue burden ofCandida species and the frequency of detection of fungemia in patients withautopsy-proven candidiasis (38). Identifying a colonized intravascularcatheter as the source of an episode of candidemia requires line removal andculture of the catheter tip. Without concomitant fungemia, the significanceof Candida species cultured from a line tip of a pyrexial patient is moredifficult to assess. Quantitative tip cultures may be performed by the rollplate method, using >15 colony forming units (cfu) per ml as the thresholdof growth indicative of catheter-related sepsis (39). Whether this threshold isapplicable to fungi is uncertain and probably irrelevant. Negative tip culturesdo not exclude catheter-related candidemia because undetected intraluminalcolonization may still be a source of infection (14). Conflicting results havebeen obtained from clinical trials evaluating the usefulness of comparativequantitative blood cultures taken through the catheter and peripherally, as ameans of diagnosing catheter-related candidemia (40,41). The techniques aretime-consuming and do not justify the laboratory effort.Leucocytosis has been reported in up to 50% ofcandidemic patients (42).

A raised serum C-reactive protein (CRP) concentration has been documentedin adults with invasive candidiasis including candidemia, although thisfinding is not specific to fungal infection (43-44). Serial measurements ofCRP levels are useful in monitoring response to therapy, rather than in thespecific diagnosis of candidiasis (45,46).Neonatal candidemia occurs most commonly in very-Iow-birth-weight

(VLBW) infants «1500 grams) and presents with abdominal distension,deteriorating respiratory function and temperature instability (47-50). Septicshock has also been reported (49). CRP measurement is an unreliablediagnostic tool in the early diagnosis of neonatal sepsis (51). Serial CRPlevels have been shown to be useful markers of the effectiveness of therapyin neonates, including some cases of confirmed candidiasis (52,53). One

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study of 121 cases of neonatal septicemia, concluded that a rise in CRPlevels beyond the third day of empirical antibiotic treatment should raisesuspicion of ineffective antibacterial treatment or a fungal infection (54).

CLINICAL DIAGNOSIS OF DISSEMINATED AND DEEPORGAN CANDIDIASIS IN ADULT INTENSIVE-CAREPATIENTS

Deep organ candidiasis may present with or without positive blood cultures(about 50% of cases) (13,15,16,55) and in single or multiple (acutedisseminated candidiasis) organs (19). The clinical presentation variesdepending on the site of infection, but frequently includes non-specific signssuch as persistent fever despite antibiotic therapy (16,42). Directexamination and culture of tissue/fluid from deep organs or sterile bodycavities, obtained by needle aspirate or biopsy, may demonstrateblastoconidia and/or pseudohyphae of Candida species, indicating invasivedisease (36). In practice, such a definitive ante-mortem diagnosis is obtainedin only a minority of ICU patients with autopsy-proven deep organcandidiasis (11).

Candida colonization in adult intensive-care patients

The most difficult task for the clinician in diagnosing invasive candidiasis isdistinguishing between simple colonization and infection. The diagnosis ofinvasive candidiasis usually relies on inferential rather than direct tissueevidence of disease. Although fungal colonization is frequent in ICU patients(up to 64% in patients ventilated for >10 days), its significance in thedevelopment of infection and its influence on mortality is unclear (10,26)Colonization has been identified as an independent risk factor forcandidemia (2,10,22). Several studies have shown that invasive candidiasisin adult ICU patients rarely occurs without any evidence of prior Candidacolonization (22,26,56). Solomokin et al. reported that 31 of 63 surgicalpatients had two or more non-contiguous sites colonized by Candida speciesprior to detection of fungemia (56). They suggested that Candidacolonization data could influence the decision to commence early antifungaltherapy in a septic patient, without direct tissue evidence of Candidainfection. A more recent study of 29 candidemic ICU patients, showed thatusing the criterion of Candida colonization at two or more distinct sitesyielded a positive predictive value for invasive candidiasis of only 44% (26).Colonization preceded infection by a mean of 25 days (range 6-70 days).The authors devised a Candida colonization index (CI) to improve the

6. Clinical Diagnosis ofFungal Infection in the Intensive Care Unit 109

predictive value of surveillance cultures in the ICU. It is defined as the ratioof the number of non-blood distinct body sites colonized by Candida speciesto the total number of body sites cultured. The corrected CI (CCI) takes intoaccount both the number of body sites and the semi-quantitative fungal loadat each site. The CCI independently predicted candidemia in this small studyand may identify a subset of patients who would benefit from earlyantifungal therapy (26). Candida colonization always preceded infectionwith genotypically identical strains. A study of 19 non-neutropenic patientssuggested that colonization with C. tropicalis at two or more non-blood siteshad a predictive value for fungemia of 100% (57), significantly higher thanthat for C. albicans colonization. Some authors have suggested thatprotracted urinary colonization is an important risk factor for invasivecandidiasis (13,57,58). Candiduria is common in catheterized ICU patientsand is consistent with both colonization and infection. A negative urineculture does not exclude invasive candidiasis (19,59). Candida speciescommonly colonize the respiratory tract and wounds of ICU patients, butrarely cause invasive disease at these sites.

Candida peritonitis

Candida peritonitis following abdominal surgery, is one of the most commonforms of candidiasis in the ICU (16). Candida species are part of normalhuman bowel flora. Thus it is not surprising that they are frequently isolatedfrom abdominal drain fluid specimens from patients with perforation of thegastrointestinal tract or post-surgical anastomotic dehiscence (13,16,42).These specimens often yield polymicrobial cultures and the clinicalsignificance of Candida isolation, in an individual patient is uncertain(60,61). Some studies have concluded that many of these isolates are ofdoubtful significance, in a clinically stable ICU patient (61). Calandra et al.(62) demonstrated that clinically relevant intra-abdominal candidiasis isprimarily associated with acute pancreatitis or refractory gastrointestinalperforations, particularly in the presence of a high initial or increasinginoculum of Candida on semi-quantitative culture of serial abdominal drainsamples. Candidiasis manifested as either peritonitis or intra-abdominalabscess and patients presented with fever, abdominal pain or distension orparalytic ileus. Equally, this study demonstrated that isolation of Candidaspecies from a supposedly sterile abdominal site does not always indicateimpending fungal sepsis (62). Candida infection may initially be confined tothe peritoneum, but has the potential to disseminate to other body sites, withserious consequences for the patient (63,64).Candida peritonitis in the ICU may also occur in the context of a patient

on continuous ambulatory peritoneal dialysis (CAPD) (16), although this

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form of renal support is used relatively infrequently in critically-ill adultpatients. The isolation of Candida species from polymicrobial peritonealfluid cultures suggests traumatic perforation of the bowel by the Tenchoffcatheter (65).

Candida infection in acute pancreatitis

The incidence of acute necrotizing pancreatitis (ANP) in Western countrieshas increased steadily over the last 20 years and occurs in around 20% ofpatients admitted to the ICU with acute pancreatitis (66,67). Secondaryinfection of devitalized tissue in the pancreas or peri-pancreatic area is thecause of 80% of deaths in acute pancreatitis (68). Candida species accountfor about 20% of microbiologically documented cases of pancreaticinfection, in either pure or mixed culture (66-69). C. albicans is the mostcommon isolate and is derived from the patients own bowel flora. A recentstudy of 37 patients showed that intra-abdominal candidiasis during ANP isassociated with a significantly higher mortality rate compared with intraabdominal bacterial infection alone (70). Patients with infected necrosispresent with refractory fever and few other signs (66,67). Computedtomographic (CT) scan with contrast enhancement is a sensitive method ofdetecting pancreatic necrosis (66). The diagnosis of pancreatic candidiasis ismade by isolation of Candida species from necrotic pancreatic tissueobtained either by CT-guided fine-needle aspiration, or at laparotomy, oralternatively from abdominal drain fluid of a patient with clinical sepsissuggestive ofANP (66,70).

Biliary tract candidiasis

Bilialy tract candidiasis may present as acute cholecystitis, cholangitis orgallstone pancreatitis (71). The presence of biliary drainage catheters is arisk factor for subsequent candidiasis (72). This infection is uncommon andthe clinical significance of yeasts isolated from the biliary tract is uncertain.Published reports have described patients with positive bile cultures ofCandida species who responded to cholecystectomy alone, withoutantifungal therapy (71). Candida colonization of the biliary tree is a wellrecognised finding in liver transplant recipients and can lead to obstructionwith subsequent ascending cholangitis (3).

Chronic disseminated candidiasis

Candida infection of deep-seated abdominal organs other than the pancreas,such as the liver or spleen, is much less common than peritonitis and is


primarily confined to patients recovering from prolonged neutropenia(15,20). Chronic disseminated candidiasis presents with refractory fever,abnonnal liver function tests and multiple lucencies in the liver and spleenon CT scan. It is definitively diagnosed by histology and culture of a biopsyor aspirate (36), although cases are often only diagnosed at autopsy (20).

Pulmonary candidiasis

Most cases of pulmonary candidiasis occur secondary to hematogenousdissemination in immunosuppressed patients, some of whom requireintensive care (73). Primary pulmonary candidiasis is a rare condition thathas been most commonly documented in oncology patients. It followsaspiration of colonized oropharyngeal or gastric contents (74). Publishedstudies in adult oncology patients report incidence rates of primarypulmonary candidiasis of around 0.2% using a variety of diagnostic criteria(74). The incidence of Candida pneumonia in the general ICU population isunknown. This is due to the difficulties in distinguishing respiratory tractcolonization from true lung infection (75-77). The definitive diagnosisdepends on histological demonstration of yeasts in lung tissue withassociated inflammation, although this is rarely made ante-mortem (73). Animmediate post-mortem histological study documented Candida pneumoniain only two of 25 non-neutropenic ventilated patients (76), who had clinicalsuspicion of pneumonia at the time of death. Candida species were isolatedfrom lung biopsies in 10 of 25 patients, which could indicate that extensiveCandida colonization is a tenninal event. The significance of Candidacultured at autopsy is uncertain. Candida species are commonly isolatedfrom ante-mortem respiratory tract cultures of ICU patients. This usuallyrepresent colonization secondary to antibiotic therapy (11). Quantitativeculture of respiratory tract specimens obtained by various sampling methods,including bronchoalveolar lavage and protected specimen brushing, does notdistinguish colonization from infection (77).Candida pneumonia (primary or secondary) presents with fever,

tachypnea and diffuse pulmonary infiltrates on chest radiograph,indistinguishable from other causes of nosocomial pneumonia (73).Disseminated miliary lesions on CT scanning have been reported inpulmonary candidiasis of hematogenous origin, although these signs are notpathognomonic (78). Primary pulmonary candidiasis may present as apneumonia, with or without an abscess, or very rarely as a mycetoma (79).

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Candida meningitis

Chapter 6

Candida meningitis occurs most commonly in neonates or young children,usually as a result ofdisseminated candidiasis (49,80). Candida meningitis inadults is often a post-neurosurgical complication, and many of these patientswill be on the ICU (81,82). Prolonged antibiotic exposure, multipleneurosurgical procedures, prior bacterial meningitis and persistentcerebrospinal fluid (CSF) leak are significant risk factors (81,83). Up to 30%of cases are caused by non-albicans species of Candida (81-83). The portalof entry may be from the patient's skin (intra- or post-operatively), byhematogenous dissemination, or by retrograde spread along the distal portionof a ventriculo-peritoneal shunt (if the distal tip has caused a perforation ofthe bowel) (81,83). Children and adults with Candida meningitis presentwith one or more of the following: lethargy, irritability, unresponsive fever,hydrocephalus and focal neurological signs (81-84). Nuchal rigidity andmeningismus are reported less frequently than in bacterial meningitis (83).The definitive diagnosis is made by examination ofthe CSF. Pleocytosis andan elevated protein concentrations are common, with either lymphocytic orpolymorphonuclear predominance (83). Gram stain ofCSF will reveal yeastsin less than 2% of cases (81). Isolation of Candida species from CSF,obtained by lumbar puncture confirms the diagnosis. A large proportion ofcases in adults are diagnosed by isolation of Candida species from CSFobtained through neurosurgical devices (82). Multiple isolations of Candidaspecies from these specimens in a patient with clinical sepsis confirms thediagnosis. However, even a single CSF isolation of Candida species,obtained from an indwelling device, in a patient with CSF indices andsymptoms consistent with meningitis is clinically significant and requirestherapy (81,82).

Intra-ocular candidiasis

Haematogenous dissemination of Candida to the eye may produce achorioretinitis, that can spread to the vitreous to cause endophthalmitis (28).The reported incidence of endophthalmitis in hospitalized patients withcandidemia varies widely (0-45%) (2,23,27-29). C. albicans is the mostcommon cause, although up to 40% of cases are caused by other species ofCandida (28). Some published reports have not distinguished betweenCandida endophthalmitis and chorioretinitis (27). The distinction isimportant, because endophthalmitis may require surgical treatment, inaddition to antifungal therapy. Serial ophthalmologic examinations areinfrequently performed on the ICU, even in those patients with suspected ordocumented candidiasis. Thus the true incidence in critical care is unknown.


Post-operative Candida endophthalmitis is rare and very few of thesepatients would require intensive care (85). If untreated, endophthalmitis canprogress to retinal necrosis and visual loss and thus early diagnosis andtreatment are essential (13,28). Cases present within days or weeks of theonset of candidemia (28). The absence of visual symptoms and theunavailability of an ocular history or visual acuity tests in mechanicallyventilated patients, hampers early diagnosis. Endophthalmitis is clinicallydiagnosed as vitreous abscess, manifesting as intra-vitreal fluff balls orchorioretinitis with extension of the surrounding inflammation into thevitreous, in a patient with documented candidemia (28). The lesions arefrequently bilateral (27,28). The definitive diagnosis is made by histologicdemonstration or isolation of Candida species from intra-vitreal biopsy,although this is rarely obtained from an ICU patient.

Urinary tract candidiasis

The majority of cases of urinary tract candidiasis are acquired by theascending route (86). A minority of adult patients with candiduria havedisseminated candidiasis with renal involvement, acquired by thehematogenous route (13). Urinary tract candidiasis presents with fever ofunknown origin, frequency, and suprapubic pain (87). The onset of rigorsand loin pain suggests pyelonephritis. C. albicans is the most commonetiologic agent, with most of the remaining cases being caused by C.tropicalis and C. glabrata. However, the true incidence of urinary tractcandidiasis in the ICU is unknown, due to the difficulty of distinguishingbetween asymptomatic candiduria and renal tract infection (88,89). MostICU patients have an indwelling urinary catheter in situ, whilst mechanicallyventilated. Candiduria is very common in catheterized patients, particularlyin elderly debilitated patients, those receiving broad-spectrum antibiotics andin diabetics (88). The presence of candiduria is consistent with any of severaldisease states, including invasive renal parenchymal disease (acquired byeither the ascending or hematogenous route), fungal balls in obstructedureters, cystitis or lower urinary tract colonization associated withcatheterization (11,19,86). The majority of patients with candiduria areasymptomatic. Candiduria tends to persist whilst the catheter is in situ,whether or not antifungal therapy is given (88-91). Solomkin has stated thatpersistently high concentrations of Candida species in the urine (>107 cfuper ml) in a septic patient who has not undergone urinary tractinstrumentation or catheterization, is suggestive of renal tract infection ofhematogenous origin (13). However, quantitative diagnostic thresholds inurine have not been validated for fungi. Neither is the presence of pyuria aconsistent indicator of infection (92). The clinical significance and natural

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history of candiduria is uncertain (86). As a result, ICU clinicians frequentlytreat patients on the basis of a single culture (93). The availability of welltolerated oral antifungal agents may have influenced clinicians in adopting amore interventional role. In a recent study of 316 hospitalized patients withasymptomatic or minimally symptomatic candiduria, 60% of whom werecatheterized, no complications of urinary candidiasis (e.g. pyelonephritis andcandidemia) were documented (86). In diabetics with poor bladder functionand renal transplant patients receiving high-dose steroids, who haveincomplete bladder emptying, there is a risk of ascending infection andpyelonephritis, with subsequent candidemia. As a result of these potentialcomplications, many clinicians would treat such patients with pre-emptiveantifungal therapy (3). Thus candiduria can in certain circumstances lead tocandidemia, although the reverse can also occur (11). Some studies havesuggested that candiduria is an early indicator of invasive candidiasis in leupatients and that candidemia without candiduria is uncommon (58). Theseauthors emphasized that candiduria should never be dismissed in a septicpatient. Other studies have found that candidemia is rarely the consequenceof candiduria and that hematogenous spread from the renal tract tends tooccur in the presence of upper urinary tract obstruction (19,94). Thesignificance of candiduria in an individual patient, as a marker of urinarytract candidiasis and/or disseminated candidiasis can only be assessed in thecontext of the overall clinical picture.

Candida mediastinitis

Candida is a rare cause of mediastinitis (5% of reported cases), but it carriesa high morbidity and mortality (95-97). The majority of cases followthoracic surgery and are caused by C. albicans (95). Deep-seated head andneck infections are another predisposing cause (96). In the precardiothoracic surgery era, iatrogenic or spontaneous esophageal perforationwas the leading cause ofmediastinitis (96). Pre- and post-operative exposureto broad-spectrum antibiotics is a common risk factor. The portal of entry ismost commonly direct intra-operative inoculation. The time to clinical onsetpost-surgery, varies from 6-100 days (median time, 10 days). The infectionpresents as fever, purulent wound drainage, chest wall erythema and sternalinstability (95). The clinical findings are indistinguishable from those ofbacterial mediastinitis. Chest radiographs may show a mediastinal mass,fluid or air. Complications occur in up to 75% of patients and includefungemia, pericarditis, empyema and sternal osteomyelitis (95-97).Definitive diagnosis requires isolation of Candida species from mediastinalfluid collected by mediastinoscopy (96), thoracotomy, or from indwelling


mediastinal drains, in a patient with clinical and/or radiological signs ofmediastinal sepsis (95).

Candida endocarditis

This is a rare condition in the ICU, but carries a high morbidity and mortality(13,16). Candida accounts for 30-44% of cases of fungal endocarditis(98,99). C. parapsilosis is a common cause of fungal endocarditis inintravenous drug abusers (100-102). Indwelling intravascular catheters,broad-spectrum antibiotics and prosthetic heart valve surgery (especiallywithin the previous 6 months) are risk factors (98). Native valve Candidaendocarditis is very uncommon. Cases in ICU patients may arise secondaryto candidemia or via direct implantation at the time of cardiac valve surgery.Clinically, the disease presents with fever and rigors unresponsive toantibiotic therapy (16,98). Embolization to major limb vessels or to the brainoccur in up to 75% of patients (101,103). Occasionally candidiasis in othersites, such as endophthalmitis, may be the only manifestation of Candidaendocarditis (104). On echocardiogram, fungal vegetations arecharacteristically large (>1 cm in diameter), left-sided (98) and occasionallynon-valvular (104). Blood cultures are positive in up to 80% of cases,although many cases are diagnosed at autopsy by histology and culture ofvegetations (98,103).

CLINICAL DIAGNOSIS OF NEONATAL CANDIDIASIS

Candida colonization in neonates

Neonatal Candida colonization rates range from 19-65% (12,47). Thecolonization rate is inversely proportional to the gestational age (47,105).Colonization develops within the first week of life in 5% of term newbornsand 24% of premature neonates (47,105-107). By two weeks of age, up to75% of neonates are colonized in at least one non-blood site. Prolongedantibiotic therapy is another recognized risk factor for neonatal Candidacolonization (47,105,108). The most commonly colonized sites are thestools, perirectum, endotracheal aspirates, urine and oropharynx (12,47,105107). C. albicans, C. tropicalis and C. parapsilosis are the most frequentisolates (12,47). Several studies in neonates have concluded that Candidacolonization is a significant risk factor for invasive candidiasis, particularlyin VLBW infants colonized in the trachea and gastrointestinal tract. Onestudy reported that five of II VLBW infants with endotracheal colonizationsubsequently developed invasive candidiasis, one to 18 days after first

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documenting a positive endotracheal aspirate culture (105). It is not knownwhether the respiratory tract serves as a portal of entry in these neonates orwhether endotracheal colonization is simply a marker of a high fungalburden. A correlation has been reported between density of fungal growth atcolonized sites and subsequent candidemia in VLBW infants (109). Huang etal. detected fungal colonization in 20% of a cohort of 116 VLBW infants.However they reported only one case of invasive candidiasis in this cohort(106). They concluded that neonatal candidiasis may occur in the absence ofcolonization, suggesting that factors other than colonization are important inthe pathogenesis of this disease. Neonatal candiduria may indicatecolonization or invasion and presents the same diagnostic problems as inadults (12). The clinical significance of Candida colonization in a neonate,can only be assessed in conjunction with the available clinical and laboratorydata.

Candidiasis in neonatal intensive care

Invasive candidiasis in neonates can present as candidemia, in the absence offocal infection (usually as intravascular catheter-associated infection), singleorgan candidiasis or as disseminated candidiasis, with or withoutdocumented candidemia (110-113). Disseminated candidiasis is verycommon in candidemic preterm infants (47,111). It usually presents atbetween 2 and 5 weeks of life (48,49,105), with non-specific signs, such asrespiratory deterioration, apnea, bradycardia, acidosis, temperatureinstability and abdominal distension (47,48,114) unresponsive to broadspectrum antibiotics, in an infant with risk factors, such as indwellingintravascular catheters. Hepatomegaly, splenomegaly and mucocutaneouslesions are variably present (47). Neonatal disseminated candidiasis has ahigher yield of positive blood cultures than in adults (up to 80% in somestudies) (48), although many cases are still only detected at autopsy (48,50).The incidence of candidemia in neonates has increased significantly in

the last 20 years (12,110,111). Candidemia has been reported in 1% ofinfants on neonatal intensive care units and in 2-4.5% of VLBW infants(110-113). The rate of infection is inversely related to birth weight andgestation age (105). Other risk factors include use of broad-spectrumantibiotics and indwelling central venous catheters, including those used forparenteral nutrition (105-107,110-113). A multicenter study of late-onsetsepsis in VLBW infants documented that 9% of septicemias were caused byfungi (107). Mortality was 28% in neonates with fungemia compared to 7%in those without fungemia. C. albicans is the causative organism in about80% of cases, C. tropicalis in around 10% and C. parapsilosis in about 5%(105-113).


Oropharyngeal candidiasis

Oropharyngeal candidiasis is the most common fungal infection in neonatesand is frequently associated with perianal Candida dermatitis (12,115,116).It usually presents in the second week of life (12). One study reported thatmucocutaneous candidiasis was a risk factor for developing invasivecandidiasis in VLBW infants (116).

Candida meningitis

Candida meningitis has been reported in up to 60% of neonates withdisseminated candidiasis (49,117). It has a high mortality rate and asignificant incidence of neurologic disability in survivors (around 12-30%)(113,118). Previous antimicrobial therapy, VLBW and pre-existing centralnervous system disease are acknowledged risk factors. It presents with nonspecific signs and CSF indices may be normal (80,117,119). Isolation ofCandida species from CSF (about 50% of cases) confirms the diagnosis incases with clinical sepsis and CSF indices compatible with meningitis (117).Some authors believe that a single positive CSF culture in the presence ofnormal CSF indices in a clinically stable neonate is insignificant (119).

Renal candidiasis

Renal involvement is a common feature of disseminated candidiasis inneonates (12). The spectrum of neonatal urinary tract candidiasis rangesfrom isolated candiduria to renal parenchymal lesions secondary to eithercandidemia, corrective urological surgery for congenital abnormalities, orascending infection (in the presence of cystitis) (111,120,121). Pelvi-uretericfungus balls have also been reported in up to 35% of neonates withcandiduria and may present with obstructive uropathy and hydronephrosis(120). Parenchymal renal candidiasis may be asymptomatic or present witholiguria, anuria, hematuria and hypertension (121,122). It is associated withcandidemia in 30-50% of reported cases, although it was often not possibleto discern whether renal candidiasis preceded, or was secondary to, afungemic episode (120,121). Non-albicans species of Candida areresponsible for around 40% of cases of renal candidiasis. Candiduria occursin 0.5-10% of neonates and, if specimens are obtained from a bag urine orvia an indwelling bladder catheter, presents the same diagnostic problems asin adults (106,121,122). Some of these patients have transient candiduriasecondary to antibiotics or perineal candidiasis, confusing the clinicalpicture. Renal ultrasound scans are used to distinguish renal candidiasis fromcandiduria without upper tract disease (121). However, because a single scan

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is not sufficiently sensitive to detect all cases of upper tract disease, someauthors advise weekly ultrasound scans in neonates treated for Candidaurinary tract infection (121). The isolation of Candida species from asuprapubic aspirate of urine is nearly always clinically significant, althougha recent questionnaire survey in the United States, revealed that someneonatologists would request a repeat aspirate, before commencingantifungal therapy (111). Some authors have suggested that diagnosticthresholds of microbial load in urine appropriate to bacterial infections canbe used to diagnose Candida urinary tract infections (120), although this hasnot been validated.

Pulmonary candidiasis

As in adults, Candida pneumonia IS rare In neonates, usually occurssecondary to hematogenous dissemination, and requires histologicexamination of lung tissue to confirm the diagnosis (47-50). Positiveendotracheal cultures for Candida species have been reported in about 25%of neonates intubated for more than 4 days (105,106). This representscolonization of the respiratory tract in most cases, and is particularlycommon in infants receiving antibiotics (106). The diagnostic utility ofbronchoscopic quantitative respiratory tract cultures has not been evaluatedin neonates, due to the narrow lumen of neonatal endotracheal tubesprecluding passage of a pediatric bronchoscope (123). Non-directedbronchial lavage techniques using narrow catheters have been evaluated forthe diagnosis of ventilator-associated pneumonia in small numbers ofneonates and produced results comparable with published data forbronchoscopic lavage in older children (124,125), although none of thepatients were diagnosed with Candida pneumonia.

Candida peritonitis

Neonatal Candida peritonitis has been reported in necrotizing enterocolitis(NEC) (50,126), as well as following gastrointestinal tract surgery orperitoneal dialysis and has a high mortality (around 50%). Candidiasis is anearly complication of intestinal surgery for NEC, occurring in 10% of cases(126). Positive peritoneal cultures for Candida species, in a neonate withclinical signs of sepsis, unresponsive to broad-spectrum antibiotics, stronglysuggest peritonitis, which may be associated with candidemia (12,16,50). Adistinct clinical entity known as spontaneous intestinal perforation (SIP) hasbeen described in premature infants (127). It typically presents in the firsttwo weeks of life and is characterized by hypotension, abdominal distension,leucocytosis, and absence of gas on abdominal radiograph. The most


commonly reported sign is blue abdominal discoloration, usually within thefirst 24 hours of illness. Early in the illness, the children appear relativelywell in contrast to neonates with NEC. Most patients with SIP requireparacentesis or laparotomy. Although it occurs much less frequently thanNEC, SIP is associated with a significantly higher incidence of candidemia(about 33%). The role of Candida species in the pathogenesis of SIP isunclear. Candida peritonitis has also been reported in neonates undergoingCAPD and is associated with a poor outcome (128).

CLINICAL DIAGNOSIS OF OTHER YEASTINFECTIONS IN THE INTENSIVE CARE UNIT

Malassezia furfur is part of normal human skin flora and is also associatedwith several skin diseases (129). Invasive M. furfur infection in adults onICU occurs most commonly in patients with hematological malignancies,usually presenting as intravascular catheter-related fungemias, clinicallyindistinguishable from candidemia (129,130). Malassezia furfur colonizesthe skin of 30-90% of hospitalized infants' (105,130,131), especially VLBWinfants and those exposed to broad-spectrum antibiotics. It causes a nonfollicular pustulosis in newborns (132) as well as catheter-related fungemia,particularly in neonates receiving parenteral lipid emulsions (115,133).Malassezia fungemia in neonates presents with non-specific signs, but feverand thrombocytopenia are common (115).Invasive Rhodotorula infections are rare and usually occur in

immunocompromised patients with indwelling intravascular catheters (134)They present with refractory fever. Septic shock has also been reported(135).

CLINICAL DIAGNOSIS OF ASPERGILLUS INFECTIONSIN THE INTENSIVE CARE UNIT

Aspergillus species were documented as causing 1.3% of nosocomialmycoses according to data from the NNIS system in the United States (I).Most of these infections were pneumonia, although a proportion of theserepresent bronchial colonization rather than infection (1,2). The incidence ofinvasive aspergillosis in non-neutropenic ICU patients is unknown due todifficulties in diagnosis. Patients may develop aspergillosis whilst on theICU (7), or be transferred for artificial ventilation because of this infection(136). High-risk groups such as transplant recipients and patients with graftversus-host disease may experience aspergillosis in the absence of

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neutropenia (20). The lung is the most common site of infection andpulmonary aspergillosis manifests as a rapidly progressive pneumonia withhigh fevers and bilateral infiltrates on chest radiographs (136). CT scan ofthe chest reveals nodules surrounded by a zone oflow attenuation (the 'halo'sign) (136-138). This finding is highly suggestive, although not completelyspecific for aspergillosis. Conversely, a normal high-resolution CT scan ofthe chest largely excludes the diagnosis of aspergillosis (20). Cultures fromsputum or bronchoalveolar lavage from patients with proven aspergillosisyield the fungus in only 25-50% of cases (137). Isolation of Aspergillusspecies from the respiratory tract of a febrile neutropenic ICU patient isstrongly predictive of invasive aspergillosis (138). However, in nonneutropenic patients, it is impossible to distinguish between infection andcolonization by culture of respiratory secretions, even when Aspergillus isisolated from bronchoalveolar fluid (137). The definitive diagnosis is madeby histologic examination of lung tissue, demonstrating tissue invasion (36).Less immunocompromised patients may develop a subacute form ofaspergillosis known as chronic necrotizing aspergillosis (20). It ischaracterized by chronic cavitating pneumonia with an indolent course.Aspergillus species may also cause skin infections at sites of intravenouscatheter insertion or prolonged skin contact with tapes or boards used tosecure intravenous catheters (139).Invasive aspergillosis is rare in neonates (140,141) and has been mainly

reported in VLBW infants. Immunosuppression, indwelling intravascularcatheters and liver dysfunction are other risk factors (140). The lung is themain portal of entry, but the skin and gastrointestinal tract are also routes ofinfection (141). Clinically, the infection presents with non-specific signs ofsepsis, unresponsive to antibiotics. Raised erythematous skin lesions andendophthalmitis have also been reported in neonates, as evidence forhematogenous dissemination ofAspergillus species (140,141).

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Chapter 7

Management of Candida Infections in the IntensiveCare UnitNorth American Perspective

JOHN E. EDWARDS, JR.Harbor/University ofCalifornia at Los Angeles Medical Center, Los Angeles, California, USA

The recovery of Candida species from patients in the intensive care unit(lCU) has become an extremely common occurrence. Candida species maybe the most common organisms recovered from the urine in the surgical ICUin most hospitals. Recovery from the sputum has also become very common,as has recovery of the organism from abdominal or thoracic drains inpatients who have had surgical procedures. Candida species are now thefourth most common organisms recovered from blood in hospitalizedpatients in the United States; most of the candidemic patients are in intensivecare.The factors associated with the emergence of Candida species to such a

high level of prevalence are relatively well known. However, the exactpathogenic mechanisms are poorly understood. The use of nearly all formsof prosthetic materials, such as indwelling catheters in both the vasculatureand in the bladder, the use of hyperalimentation fluids, and the use ofpowerful, broad-spectrum antibiotics are extremely important modalities thathave been associated with Candida infections. Additionally, steroids,cytotoxic drugs for cancer chemotherapy, and immunosuppressive agents toprevent transplanted organ rejection are also important risk factors. Bumpatients and low-birth-weight infants in neonatal ICUs are also susceptible toCandida infections. An important characteristic of Candida species is thatthey have a very high propensity to adhere to prosthetic materials, includingplastic and metal. Undoubtedly this adherence property is criticallyimportant in the pathogenesis ofmany forms of Candida infection that occurin the ICU setting.

In parallel with the increasing incidence of Candida infections, there is acritical need to develop the most effective therapeutic and prevention

130 Chapter 7

strategies. However, the number of controlled, comparative, and blindedclinical trials is very small; the database from which to derive guidelines fortherapeutic recommendations lags far behind the increasing need. Therefore,nearly all guidelines are based on a synthesis of the limited available dataand the clinical judgement of the guideline writers. With regard to guidelinesfor Candida infections, three distinct categories can be defined. One is asingle author or institution set of recommendations (l,2), a second is aconsensus conference of experts with publication of the deliberations (3),and a third is a document written by a committee of experts and approved bythe governing council of the scientific society that commissioned the report.The intention of this chapter is to integrate all three approaches withcommentary, and focus the recommendations on the ICU environment.

MANAGEMENT OF CANDIDEMIA

Until approximately two decades ago, Candida species were thought onlyrarely to cause infection and the organisms were considered 'weak'pathogens. However, it has become clear that these organisms are capable ofcausing lethal infections. When they enter the bloodstream they can causedevastating infections in the deep organs, especially the brain, heart, eye, andkidney (4). In 1979, the first azole drugs were introduced for themanagement of serious fungal infections and were considered far less toxicthan amphotericin B. In 1990, the triazole, fluconazole, was introduced andin 1994, the first blinded, comparative, multicenter, prospective study offluconazole versus amphotericin B was completed by the National Institutesof Health Mycoses Study Group (MSG) in the United States. This studyshowed that fluconazole was an acceptable alternative to amphotericin B forthe management of candidemia.With the introduction of the less toxic azoles, a very strong consensus

developed to treat all patients with candidemia with an antifungal drug (3).This consensus was based on two factors: first, an appreciation of theunacceptably high rate of failure in distinguishing which patients withCandida in the blood had only 'transient' candidemia and which patients haddeep organ infection, and secondly, an appreciation of the high mortalityrates associated with candidemia.

Candida species can be recovered from the blood via a peripheral venouspuncture, through an indwelling catheter, from an arterial puncture, or fromthe tip of a catheter that has been removed and cultured. Unfortunately,sufficient data do not exist to develop a differential in the significance ofrecovery from these various sites. This author suggests attributing the samesignificance to all these methods of recovery and advocates treating with an

7. Management ofCandida Infections in the Intensive Care Unit 131

antifungal agent on the assumption that the organism has had an opportunityto disseminate widely. Additionally, data suggest that, if it is feasible, allindwelling intravenous lines should be changed, and preferably inserted intonew sites, in candidemic patients (5,6). Whether intra-arterial lines needchanging is less clear. Until further data are developed regarding these lines,they should be changed also, if at all feasible. This author does notrecommend the routine culturing of the tip of removed indwellingintravenous lines in all patients, but would culture the tip in those individualsat high risk for disseminated candidiasis.In non-neutropenic candidemic patients who are clinically stable (i.e., do

not have an unexplained fever, are generally improving, and are nothypotensive), treatment with fluconazole has become popular (7-'9). In thosepatients who are not stable (i.e., have unexplained fever despite appropriateantibacterial antibiotics, are deteriorating generally, or are hypotensive),amphotericin B is the first choice therapy for most investigators. While thedata are less clear regarding equivalency between fluconazole andamphotericin B in neutropenic patients, there has evolved a lower thresholdfor using fluconazole in those neutropenic patients who are stable.In recent years the recovery of non-albicans species of Candida has

become increasingly more common (10). In many institutions, C. albicansaccounts for only approximately 50% of the Candida isolates. Of the nonalbicans species, two are particularly important because of their potentialresistance to fluconazole. C. glabrata has intermediate susceptibility and C.krusei, less commonly recovered, is considered intrinsically resistant tofluconazole (11). Therefore, determining the precise identity andsusceptibility of a Candida isolate is now critically important. In mostlaboratories, determining whether an isolate is C. albicans or a non-albicansspecies can be done on the day of isolation. Within one to two days theprecise species can be determined. For patients in whom there is a concernregarding a non-susceptible species of Candida, amphotericin B should beused until the isolate has been identified.In the United States there has been an increasing propensity to use

fluconazole at a dose of 800 mg per day in candidemic patients. Thisapproach has resulted from the very low toxicity of fluconazole found withdoses of 400 mg per day in the comparative trial with amphotericin B (12),and the residual fatality rate in both groups. The use of doses of 800 mg perday is above the approval level of the Food and Drug Administration. A newtrial of the treatment of candidemia is in progress. A dose of 80 mg per dayof fluconazole has been chosen as one of the comparators (13).The length of time a candidemic patient needs to be treated has not been

defined. Most clinicians are using the same approach as incorporated intoclinical trials. This is to treat for two weeks beyond the last positive blood

132 Chapter 7

culture. Whether amphotericin B in combination with fluconazole is asuperior strategy is currently under investigation within the MSG (13).Another popular strategy has been to treat unstable patients withamphotericin B and, when they become stable, to change to therapy withfluconazole.

MANAGEMENT OF RECOVERY OF CANDIDA SPECIESFROM THE SPUTUM IN INTENSIVE-CARE PATIENTS

The recovery of Candida species from the sputum of ICU patients hasbecome an extremely common phenomenon (14). Because Candida speciesare part of the oral flora in most individuals, recovering them in significantquantities from patients who have been subjected to broad-spectrum, longterm antibiotics is to be expected. Additionally, patients with oropharyngealcandidiasis may aspirate organisms into the tracheobronchial tree.For reasons that are not clear, Candida species only infrequently cause

pneumonia as secondary invaders following a bacterial pneumonia (15-19).Therefore, a substantial majority of patients who have Candida speciesrecovered from the sputum do not have a Candida pneumonia. To establishwhether Candida pneumonia is actually present requires biopsy proof ofinfection of pulmonary parenchyma with the organism. If a patient is to betreated for presumptive Candida pneumonia without biopsy proof, only thosewith a refractory infiltrate who have been treated extensively with theappropriate antibacterial antibiotics, and who repeatedly grow Candidaspecies from the sputum, should be selected. Not infrequently, patients whoare producing Candida species in the sputum also produce the organismsfrom other sources, such as the urine or abdominal drains. When thesepatients have been subjected to multiple risk factors for hematogenouslydisseminated candidiasis, they often receive either amphotericin B orfluconazole as empiric therapy.There is another form of Candida pneumonia that is rare and occurs in

the setting of severe neutropenia. Multiple 'miliary' foci of infection appearthroughout the lung as a result of hematogenous dissemination. This form ofCandida pneumonia usually occurs as a preterminal event and is recognizedby the characteristic radiographic appearance.


MANAGEMENT OF CANDIDA SPECIES RECOVEREDFROM THE URINE OF INTENSIVE-CARE PATIENTS

Candida species may be the most common organisms recovered from theurine of patients in surgical ICUs in most major medical centers of theUnited States at this time (20). The two factors that are probably responsibleare the use of powerful, broad-spectrum antibiotics, and the use ofindwelling bladder catheters.There is a general consensus that patients who have candiduria in the

presence of an indwelling bladder catheter, and who do not have eithersymptoms of a urinary tract infection or pyuria, should have the catheterchanged as the only therapeutic approach (20). Patients in this category willonly form a minority of those in an ICU, since frequently these patients havepyuria and/or are growing Candida species from other sites and are at riskfor widespread disseminated candidiasis. There has been a growing concernthat Candida in the bladder may be a source for hematogenouslydisseminated candidiasis, especially in neutropenic patients (21-26).Therefore, in neutropenic patients who are at high risk for hematogenouscandidiasis, who develop candiduria associated with an indwelling bladdercatheter, and who do not clear the candiduria with change of the catheter, themost conservative approach is to undertake a trial of antifungal therapy. Thistrial would be aimed at both eliminating the bladder as a possible source forhematogenous dissemination and to empirically cover for the presence ofoccult hematogenous dissemination.Fluconazole, given orally (3,20), is currently considered the treatment of

choice for urinary tract candidiasis. It is much easier to administer thanperforming a bladder wash-out procedure with amphotericin B (27).However, the species of Candida and its antifungal drug susceptibilitiesmust be taken into consideration when choosing the appropriate therapy. Inpatients undergoing an operative procedure on the urinary tract, coveragewith an antifungal is now advised to reduce the risk of disseminatedhematogenous candidiasis.

MANAGEMENT OF CANDIDA SPECIES RECOVEREDFROM ABDOMINAL DRAINS IN POSTOPERATIVEINTENSIVE-CARE PATIENTS

Recovery of Candida species from abdominal drains in postoperative ICUpatients has also become a common occurrence. Interpreting the significanceis difficult and similar to interpreting the recovery of Candida species fromsputum (28,29). Only biopsy of either the peritoneum or an intra-abdominal

134 Chapter 7

organ can definitively establish the presence of infection as opposed tocolonization of the drains. The decision to treat a patient with an antifungalagent, if Candida species are recovered from the abdominal drains, must bemade within the overall clinical context. For instance, if Candida isrepeatedly recovered from the drains and the patient is febrile, even thoughappropriate antibacterial antibiotics have been administered, and is at highrisk for hematogenously disseminated candidiasis, therapy should be given.Appropriate imaging procedures, to determine whether an intra-abdominalabscess is present, may be a helpful diagnostic approach as well.Alternatively, if the patient is clinically stable and is only occasionallygrowing Candida species from the drains, is asymptomatic with respect to apossible peritoneal infection or an intra-abdominal abscess, and is notgrowing Candida species from other sites, therapy may not be needed. Ingeneral, the threshold for treating patients who repeatedly grow Candidaspecies from drains has been lowering.The choice of antifungal agent is either oral fluconazole or amphotericin

B. The choice is made according to criteria already described for otherclinical situations. Intra-abdominal amphotericin B has been used. However,most patients experience considerable abdominal pain from local instillationof amphotericin B. In cases where Candida peritonitis has developed duringthe course of peritoneal dialysis, it is preferable to remove or change thedialysis catheter. However, there are reports of successful therapy withoutchanging the catheter. It is also necessary to tailor treatment to the speciesand susceptibilities of the organisms recovered.

PROPHYLACTIC AND EMPIRIC THERAPY FORCANDIDA INFECTIONS IN THE INTENSIVE CAREUNIT

There are no firm guidelines for either prophylactic or empiric strategies forantifungal drug use in ICU patients. In general, prophylaxis is not advised asa routine procedure for patients in the ICU. However, a prophylaxis strategyshould be determined within the context of the occurrence of fungalinfections in a given institution. One of the major concerns regarding theliberal use ofprophylaxis is the development of large populations ofCandidaorganisms that are resistant to currently available antifungal agents.However, there are certain patient populations for whom prophylaxis isrecommended, who are at high risk for Candida infection. They includepatients receiving treatment for acute myelogenous leukemia, patientsreceiving allogeneic or high-risk autologous bone marrow transplants, andpatients receiving high-risk liver transplants. Trauma patients who have


disruption of the bowel integrity with peritoneal soiling, and in whomCandida species are recovered at the time of surgery, are also frequentlygiven prophylaxis. A recent study of prophylaxis in the ICU showed adefinite benefit with the use of fluconazole (30). This study was conductedin a setting where the incidence of disseminated candidiasis was very highand patients were very ill. It shows the value of prophylaxis in theappropriate setting, and opens the door for further studies.The choice of prophylactic agent has included fluconazole for patients

thought not to be at high risk for Aspergillus infection. For those at high riskof aspergillosis, low dose amphotericin B has been used (31). Intravenousitraconazole has recently become available. The effectiveness of its useneeds to be thoroughly evaluated, especially with regard to prevention ofAspergillus infection. A recent meta-analysis of 2181 patients has shown theusefulness of oral itraconazole in preventing proven fungal infection inneutropenic patients (32). Other therapeutic agents that cover a broaderspectrum of Candida species, as well as Aspergillus species, are underdevelopment. They include the echinocandins and advanced generationazoles (33, 34).For empiric treatment of neutropenic patients with fever that has been

unresponsive to antibacterial antibiotics, an agent that covers a broadspectrum of Candida species, as well as Aspergillus species, isrecommended. A recent large study comparing liposomal amphotericin B(AmBisome) (3mg/kg daily median dose) to the conventional deoxycholateformulation of amphotericin B (0.6 mg/kg per day median dose) has shownequivalency in the primary analysis. A secondary analysis has shownsuperior tolerance and safety and a decreased rate of documentedbreakthrough fungal infections, especially in bone marrow transplantpatients (35). Whether liposomal amphotericin B will replace conventionalamphotericin B for this indication is controversial and remains to bedetermined. The role of intravenous itraconazole, the echinocandins andadvanced generation azoles will undoubtedly be determined within the nexttwo to three years. No studies regarding the comparative use of antifungalsfor the empiric treatment of non-neutropenic patients have been published todate.

MANAGEMENT OF OTHER TYPES OF CANDIDAINFECTIONS

The management of other types ofCandida infections is beyond the scope ofthis discussion, since they are not directly related to considerations thatinvolve the ICU. Examples are Candida osteomyelitis, Candida pericarditis,

136 Chapter 7

and chronic hepatosplenic candidiasis. The reader is referred to other sourcesfor these entities (3,4,20,33,34).

CONCLUSION

The management of Candida infections in the ICU is complex and requiresan integration of the clinical factors of a given patient. The most importantissue is when to use empiric therapy in these patients. In this discussion, anattempt has been made to rely heavily on recent therapeutic guidelines and totailor them specifically to the clinical situations most likely to occur in theICU. The prevalence and incidence of Candida infections will likelycontinue to increase. Of encouragement is the development of newerantifungal agents, belonging to new pharmacological classes, that may notonly have a broader spectrum of activity but may also diminish or counteractthe development of drug resistance among Candida species.

REFERENCES

1. Edwards JE, Filler SG. Current strategies for treating invasive candidiasis: emphasis oninfections in nonneutropenic patients. Clin Infect Dis 1992;14(Suppll):SI06-SI13.

2. SwerdlofI lN, Filler SG, Edwards JE. Severe Candidal infections in neutropenic patients.Clin Infect Dis 1993;17(Suppl 2):S457-S467.

3. Edwards JE, Bodey GP, Bowden RA, et al. International conference for the developmentof a consensus on the management and prevention of severe Candida Infections. ClinInfect Dis 1997;25:43-59.

4. Mandell GL, Bennett JE, Dolin R. In: Mandell, Douglas, and Bennett's Principles andPractice ofInfectious Diseases. 5th edn. Philadelphia: Churchill Livingstone, 2000: 1728.

5. Rex JH, Bennett JE, Sugar AM, et al. Intravascular catheter exchange and duration ofcandidemia. NIAID Mycoses Study Group and the Candidemia Study Group. Clin InfectDis 1995;21:994-6.

6. Rex JH. Editorial response: catheters and candidemia. Clin Infect Dis 1996;22:467-70.7. Anaissie EJ, Rex JH, Uzun 0, Vartivarian S. Predictors of adverse outcome in cancer

patients with candidemia. Am J Med 1998; I04:238-45.8. Nguyen MH, Peacock JE, Tanner DC, et al. Therapeutic approaches in patients with

candidemia. Evaluation in a multicenter, prospective, observational study. Arch InternMed 1995;155:2429-35.

9. Phillips P, Shafran S, Garber G, et al. Multicenter randomized trial of fluconazole versusamphotericin B for treatment of candidemia in non-neutropenic patients. CanadianCandidemia Study Group. Eur J Clin Microbiol Infect Dis 1997;16:337-45.

10. Pfaller MA, Jones RN, Messer SA, Edmond MB, Wenzel RP. National surveillance ofnosocomial blood stream infection due to species of Candida other than Candidaalbicans: frequency of occurrence and antifungal susceptibility in the SCOPE Program.SCOPE Participant Group. Surveillance and Control of Pathogens of Epidemiologic.Diagn Microbiol Infect Dis 1998;30: 121-9.


II. Rex JH, Rinaldi MG, Pfaller MA. Resistance of Candida species to fluconazole.Antimicrob Agents Chemother 1995;39: 1-8.

12. Rex JH, Bennett JE, Sugar AM, et al. A randomized trial comparing fluconazole withamphotericin B for the treatment of candidemia in patients without neutropenia. N Engl JMed 1994;331: 1325-30.

13. Rex JH, Pappas PG, Karchmer AW, et al. A randomized and blinded multicenter trial ofhigh-dose fluconazole (F) and placebo (P) vs. F and amphotericin B (A) as treatment ofcandidemia in non-neutropenic patients. Abstracts of the 41 st Interscience Conference onAntimicrobial Agents and Chemotherapy. Washington DC, American Society forMicrobiology, 200 I; abstract J681 a, p.378.

14. Pfaller MA. Nosocomial candidiasis: emerging species, reservoirs, and modes oftransmission. Clin Infect Dis 1996;22:S89-S94.

15. Haron E, Vartivarian S, Anaissie E, Dekmezian R, Bodey GP. Primary Candidapneumonia. Experience at a large cancer center and review of the literature. Medicine(Baltimore) 1993;72: 137-42.

16. Masur H, Rosen PP, Armstrong D. Pulmonary disease caused by Candida species. Am JMed 1977;63:914-25.

17. El-Ebiary M, Torres A, Fabregas N, et al. Significance of the isolation of Candidaspecies from respiratory samples in critically ill, non-neutropenic patients. An immediatepostmortem histologic study. Am J Respir Crit Care Med 1997; 156:583-90.

18. Rello J, Esandi ME, Diaz E, et al. The role of Candida sp. isolated from bronchoscopicsamples in nonneutropenic patients. Chest 1998;114:146-9.

19. Connolly JE, McAdams HP, Erasmus JJ, Rosado-de-Christenson ML. Opportunisticfungal pneumonia. J Thoracic Imaging 1999; 14:51-62.

20. Rex JH, Walsh TJ, Sobel JD, et al. Practice guidelines for the treatment of candidiasis.Infectious Diseases Society ofAmerica. Clin Infect Dis 2000;30:662-78.


22. Kauffman CA, Vazquez JA, Sobel JD, et al. Prospective multicenter surveillance studyof funguria in hospitalized patients. The National Institute for Allergy and InfectiousDiseases (NIAID) Mycoses Study Group. Clin Infect Dis 2000;30: 14-8.

23. Taylor GD, Buchanan-Chell M, Kirkland T, McKenzie M, Wiens R. Trends and sourcesof nosocomial fungaemia. Mycoses 1994;37:187-190.

24. Nassoura Z, Ivatury RR, Simon RJ, Jabbour N, Stahl WM. Candiduria as an early markerof disseminated infection in critically ill surgical patients: the role of fluconazoletherapy. J Trauma 1993;35:290-4.

25. Gubbins PO, Piscitelli SC, Danziger LH. Candida urinary tract infections: acomprehensive review of their diagnosis and management. Pharmacotherapy1993;13:110-27.

26. Ang BS, Telenti A, King B, Steckelberg JM, Wilson WR. Candidemia from a urinarytract source: microbiological aspects and clinical significance. Clin Infect Dis1993; 17:662-6.

27. Hsu CC, Ukleja B. Clearance of Candida colonizing the urinary bladder by a two-dayamphotericin B irrigation. Infection 1990;18:280-2.

28. Calandra T, Bille J, Schneider R, Mosimann F, Francioli P. Clinical significance ofCandida isolated from the peritoneum in surgical patients. Lancet 1989;ii: 1437-40.

29. Spiechowicz E, Santarpia RP, Pollock JJ, Renner RP. In vitro study on the inhibitingeffect of different agents on the growth of Candida albicans on acrylic resin surfaces.Quintessence Int 1990;21 :35-40.

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30. Pelz RK, Hendrix CW, Swoboda SM, et al. Double-blind placebo-controlled trial offluconazole to prevent candidal infection in critically ill surgical patients. Ann Surg2001 ;233:542-8.

31. Perfect JR, Klotman ME, Gilbert CC, et al. Intravenous amphotericin B in neutropenicautologous bone marrow transplant recipients. J Infect Dis 1992;165:891-97.

32. Glasmacher A, Hahn C, Molitor E, Marklein G, Schmidt-Wolf I. Itraconazole forantifungal prophylaxis in neutropenic patients: a meta-analysis of 2181 patients.Abstracts of the 41 st Interscience Conference on Antimicrobial Agents andChemotherapy. Washington DC, American Society for Microbiology, 2001; abstractJ681, p.378.

33. Ally R, Schurmann D, Kreisel W, et al. A randomized, double-blind, double-dummy,multicenter trial of voriconazole and fluconazole in the treatment of esophagealcandidiasis in immunocompromised patients. Clin Infect Dis 2001 ;33: 1447-54.

34. Villanueva A, Arathoon EG, Gotuzzo E, et al. A randomized double-blind study ofcaspofungin versus amphotericin for the treatment of candidal esophagitis. Clin InfectDis 2001 ;33: 1529-33.

35. Walsh TJ, Finberg RW, Arndt C, et al. Liposomal amphotericin B for empirical therapyin patients with persistent fever and neutropenia. National Institute of Allergy andInfectious Diseases Mycoses Study Group. N Engl J Med 1999;340:764-71.

Chapter 8

Management of Candida Infections in the IntensiveCare UnitEuropean Perspective

NEIL SONIChelsea and Westminster Hospital, London, United Kingdom

There is little doubt that fungal infections are becoming more common incritically-ill patients. The reasons for this are many and various. Sickerpatients and the widespread use of potent broad-spectrum antibiotics have arole, but part of the picture must be an increasing awareness amongstclinicians and a lower threshold for diagnosis.

In many respects the model currently used for the diagnosis andtreatment of fungal infection in the critically-ill patient comes directly fromthe treatment of the immunocompromised patient. However, there are somemajor fundamental differences between these populations (Table 1). In theimmunocompromised patient there is an inherent vulnerability to fungalinfection which is easily recognized and is correctly perceived as a majorthreat. The underlying disease process in these patients is relatively easilydefined as are the attributable morbidity and mortality associated with thatcondition. Even in such patients who do find their way into the intensivecare unit (leU), often as a direct consequence of infection, the attributablemortality from that infection can be estimated based on the prognosis for theunderlying condition. It would be naIve to describe this scenario as relativelysimple, but it is not cluttered with multiple confounding factors. The risk ofdeveloping fungal infection is known and is potentially quantifiable, theimpact of that infection is also known and the problems of treatment areidentified. The risks from treatment in terms of aggravating organ systemfailure are relatively small.

In contrast, the critically-ill population are heterogenous by nature andtheir underlying problem often carries a high potential mortality. In themajority of critically-ill patients who are vulnerable to fungal infection thereasons for that vulnerability are multiple and the levels of risk are

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impossible to accurately define. Overt immune suppression to the level ofthe patient on chemotherapy is relatively uncommon whilst relative immunesuppression is often assumed to be present. Other factors, such as damagedintegument, overgrowth of fungus, and indwelling catheters, all playa part.These patients often have extreme vulnerability to organ failure and renal orliver failure may be present even before their fungal infection. Both thefungal infection and its treatment can potentially make the situation worse.In these patients, attempts have been made to define attributable mortalityand it is said to be high. It is high. Patients who are sick enough to developfungal infection are usually sick enough to die and in some respects thedevelopment of a systemic fungal infection could be seen as a measure oftheir acute physiological derangement. Fungal infection is a clinical signwith a clinical message. It is therefore inevitable that a rigorous approach totreatment of fungal infection must be adopted as a proportion of thesepatients will be salvageable, but not if the fungal disease is allowed to run itscourse. In this respect these patients are similar to the immunocompromisedpopulation in broad terms.

Table I. General differences between immunocompromised and critically-ill populations

MechanismUnderlying problemsImmune system problemRelevance of underlyingproblemRisk assessment of likelihoodof fungal infectionPhysiological derangementOrgan systems

Attributable mortalityTreatment toxicity

ImmunocompromisedSingle/simpleDefinedDirect

Simple

MinimalReasonable condition

Direct relationshipUnlikely

Critically-illMultipleNon-specificIndirect

Difficult

ExtensiveOften damaged; alwaysvulnerableIndirect and difficult to assessProbable

It is clear that the immunocompromised population and the critically-illpopulation are very different. It is my view that the model for diagnosis andtreatment in the immunocompromised population needs to be modified to besuitable for the critically-ill population.Before describing my approach to treatment there are two central

considerations that need to be addressed. The first is the nature of the fungalinfection being treated and the second, which is related to the first, is thecharacteristics of the available antifungal agents. In this chapter we areconsidering Candida sepsis, but under this generic heading infection may becaused by a number of Candida species which differ widely in theirsusceptibility to the available drugs. For this reason, there can be no one


approach to Candida sepsis that will satisfy all situations just as there is noone universal therapeutic approach to gram negative sepsis. As will becomeclear during this chapter, there have been major changes in the managementof fungal infections as a result of the introduction of new agents and thistrend is likely to accelerate as more agents are developed.

THE DISTRIBUTION OF CANDIDA SPECIES IN THEINTENSIVE CARE UNIT

Each ICU is an individual ecosystem. It is important to be aware of thespecies present in individual units rather than assuming that any particularunit will conform to the national average. National or internationalsurveillance data are useful indicators of general patterns of change and maybe helpful in following trends in drug susceptibility. In the SENTRY study,conducted in ICUs in 20 European centers, C. albicans was the mostcommon organism (53%), followed by C. parapsilosis (21%), C. glabrata(12%), C. tropicalis (6%), C. famata (2%), C. krusei (1%), and C.inconspicua (1%) (1). It is interesting to note that there appears to have beenlittle change in the pattern of species distribution between 1992 and 1998,although among the non-albicans species of Candida, C. glabrata nowappears to be more common than C. parapsilosis (2). In terms ofsusceptibility, 100% of bloodstream isolates of C. krusei and 8.7% of C.glabrata isolates, collected in 1997 in the United States, Canada and SouthAmerica as part of the SENTRY program, were found to be resistant tofluconazole (3). In the same study, 66% of C. krusei isolates and 36 % of C.glabrata isolates were resistant to itraconazole.National surveillance data give a broad picture and indicate changing

patterns of resistance, but are not necessarily relevant to the individual ICU.Local knowledge of which species are most prevalent and an awareness ofwhether resistance problems exist are of considerable clinical relevance (4).In the ICU in which I work, almost all of our Candida isolates tend to be C.albicans and only occasionally are other species isolated. To date, all C.albicans isolates recovered from our ICU patients have been susceptible tofluconazole, even though resistant strains have been encountered elsewherein the institution (among persons with HIV infection) (5-7). In my opinion,high-dose fluconazole may be suitable for some cases of non-albicansCandida infection. Because it is increasingly common to use a higher doserange of this agent in Candida sepsis, this may simplify the decision makingprocess. Nevertheless some isolates of C. glabrata are resistant tofluconazole and it is important to determine the susceptibility of isolates of

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this organism before proceeding. C. krusei infections should not be treatedwith fluconazole and C. tropicalis is not predictably susceptible.

CHARACTERISTICS OF THE AVAILABLEANTIFUNGALAGENTS

Amphotericin B remains the gold standard for treatment of many systemicfungal infections. The traditional preparation of this drug is formulated as amicellar dispersion with sodium deoxycholate acting as a surfactant. Itaggregates in normal saline, but can be administered in 5% dextrose.Following intravenous administration, it is widely distributed with highconcentrations being achieved in the kidneys, spleen and liver. It isextensively protein bound (>90%) and concentrates poorly in body spaces. Itis found at very low concentrations in the cerebrospinal fluid. AmphotericinB has an initial serum half-life of 24-48 h and an elimination half-life ofapproximately 2 weeks. It is metabolized to a limited extent by the liver andsome is excreted in both the bile and in the urine. However, even a year afteradministration, it is still possible to detect the drug in the liver.The maximum daily dosage of the conventional formulation of

amphotericin B is in the order of 1.0 mg/kg per day. The toxicity of the druglimits the maximum achievable concentration of amphotericin B and mayaccount for some treatment failures where the MIC of the infecting Candidaisolate has been high. Infusion of the drug may be associated with chills andflushing from vasodilatation, often associated with fever. This can beavoided by very slow infusion. Nausea and vomiting are common. In thecritically-ill patient, the main problem is nephrotoxicity although thereported incidence of renal damage is extremely variable (8,9). Methods ofavoiding nephrotoxicity include volume loading, particularly sodium loadingprior to administration of the drug. Hypokalemia is also seen.Three new lipid-based formulations of amphotericin B have been

approved for use in humans: liposomal amphotericin B (LAB, AmBisome),amphotericin B colloidal dispersion (ABCD, Amphocil or Amphotec), andamphotericin B lipid complex (ABLC, Abelcet). These new formulationshave significant advantages over the conventional deoxycholate preparationin that they are much less nephrotoxic and appear to be at least as active asthe parent compound (10-14). Now that these lipid-based preparations ofamphotericin B are available, there is, in my opinion, no place for theoriginal formulation in the treatment of critically-ill patients who arevulnerable to organ system failure and may well be exposed to otherpotential insults to renal function.


In the case of LAB, the drug is encapsulated in phospholipid-containingliposomes. Less than 5% of the drug is released from the liposomes duringthe first 72 h after administration. The basic mechanism of action is similarto of the parent compound, but it has been suggested that there may also be asynergistic effect between LAB and macrophages (15). There is apredisposition for the liposomes to be trapped in the reticuloendothelialsystem so that dosages of 3-5 mglkg per day achieve concentrations in theliver and spleen 10 times those seen with conventional amphotericin B (16).LAB probably persists in the reticuloendothelial system for a long time. It isnot cleared by hemofiltration. The optimum daily dosage of this formulationis unclear, but 3 mg/kg reducing to 1 mg/kg after 3 days appears reasonableat the present time.

In the case of ABCD, the drug is complexed with cholestryl sulphate toform small lipid discs. Levels in renal tissue are much lower than are seenwith the conventional formulation, but concentrations in the liver are muchhigher. In most cases, ABCD has been used at dosages of 3-4 mg/kg per day,but doses up to 7.5 mglkg day have been employed. It is less toxic thanconventional amphotericin B and this has been confirmed in animal modelswhere dosages up to 8 times those of amphotericin B deoxycholate havebeen shown to be safe. No nephrotoxicity was seen in a clinical trial in 75bone marrow transplantation recipients (17). Elsewhere, in a series of studiesinvolving 572 patients the main side effects were chills and fever. Theoverall incidence of nephrotoxicity was 16%, lower than with conventionalamphotericin B. There was no difference between baseline and end oftreatment creatinine values (18-21).

In the case of ABLC the drug is complexed with two phospholipids toform ribbon-like structures. Compared with LAB, ABLC contains a higherproportion of the parent compound. ABLC is rapidly removed from thecirculation and is mainly deposited in the reticuloendothelial system. Thereis relatively little spontaneous release of free amphotericin B. In clinicaltrials, the response rates have been variable, but comparable with theconventional formulation. Nephrotoxicity is reduced. In patients with normalcreatinine levels, only 10% showed a rise in creatinine on treatment, and insome of them the creatinine levels then fell during treatment (10).The issues are simple. Lipid formulations of amphotericin Bare

expensive, but effective. The three preparations have not been comparedwith each other in clinical trials, but only with conventional amphotericin Bwhere all three have a better safety profile. In general, the data on efficacyare limited, but encouraging. The data in the critically-ill are effectively nonexistent and must be extrapolated from other situations. At present, the newformulations represent a significantly less toxic and genuine alternative toconventional amphotericin B, especially in vulnerable patient populations.

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At present, the principal alternative to amphotericin B is the triazoledrug, fluconazole, which can be given either orally or intravenously (22).This agent has a large volume of distribution, corresponding to total bodywater, and a relatively low protein binding (about 12%). It thereforepenetrates tissues, including the central nervous system, the eye and sputum,extremely well (23,24). Fluconazole has a serum half-life of up to 30 h. It iseliminated by glomerular filtration (90%) and the half-life may be prolongedin patients with impaired renal function (25). It has some side-effects,including nausea and vomiting, headache, fatigue and abdominal pain.Transient elevations in liver enzymes, both aminotransferases and alkalinephosphatase, occur in a small percentage of patients (26,27). This isuncommon and is usually associated with the higher dosage regimens.Interactions may occur with warfarin, cyclosporin and phenytoin resulting inaltered plasma levels.It has been suggested, although there is no substantial evidence to support

this, that exposure to azoles may predispose to the emergence of resistance(28). Therefore, routine use of low dose prophylaxis with fluconazole mightbe envisaged as a potential cause of the emergence of resistance to the agent.On the other hand, high dose therapy is becoming increasingly popular withdoses of 800mg per day. Such dosages have been associated with goodresponses and relatively few side-effects. It has been suggested that doses ofup to 1600 mg per day are well tolerated by most patients, but this is basedon a limited number of cases (29-32).Other azoles are now in use. Itraconazole has an oral bioavailability of

about 55%. It is metabolized by the liver and therefore dosage may need tobe adjusted in liver disease. The investigational agents, voriconazole andposaconazole also show promise. The possibility of using oral agents ratherthan intravenous agents has never been considered relevant in the criticallyill, but with the increasing use of the gastrointestinal tract for feeding duringsevere illness, it is likely that this route will become more popular. What isneeded are data to indicate effective absorption of drugs under thesecircumstances. At the present time, the oral route is probably not advisablefor initiation of therapy, but it may have a role and advantages during therecovery phase. In particular, it may offer an economic advantage.

Amphotericin B and fluconazole compared

It is relevant at this point to consider the relative merits of fluconazole andLAB, the latter being chosen to represent the various lipid-basedformulations of amphotericin B that are now available to treat the criticallyill patient. In terms of toxicity, both abnormal liver function and impairedrenal function are common in the critically-ill with or without antifungal


treatment. The problem is that these effects may be drug related. Fluconazoleis occasionally associated with elevations in liver enzyme levels, while LABhas the potential to cause renal toxicity, albeit to limited extent. Both drugshave much better toxicity profiles than conventional amphotericin B.The modes of action of fluconazole and LAB are different. The former is

a fungistatic compound while the latter may be fungicidal. This shouldconfer an advantage on LAB and there are still those who considers thenewer azoles to be less potent than amphotericin B. However, data tosupport this contention are lacking and, indeed, recent data suggest this isnot true. The pharmacokinetics of the two agents are very different:fluconazole is widely distributed while LAB tends to accumulate in thereticuloendothelial system. It has been suggested that this is why the lipidbased formulations may be less effective for mucocutaneous manifestationsof Candida sepsis. On the other hand, the higher concentrations of LAB inthe reticuloendothelial system may confer benefit in systemic fungalinfection, although this is conjectural.There are more documented reports of acquired resistance to fluconazole

than to amphotericin B and the azole compound does have a much morelimited spectrum of activity. In terms of cost, fluconazole is certainlycheaper than LAB, although it would be an error to consider any antifungaldrug as 'cheap and cheerful' .

Treatment of Candida albicans infection

Because C. albicans is the most common Candida species encountered inmost rcus, it is relevant to examine the options for treating this organism.This is a complex issue. Traditionally, amphotericin B has been the mainstayof treatment. The drug is fungicidal and its advocates suggest that there arestill inadequate data in the critically-ill to support the use of either the lipidbased formulations or an azole. The data relating to comparisons betweenlipid-based and conventional formulations of amphotericin B have alreadybeen reviewed. They are, in my opinion, adequate to support the contentionthat conventional amphotericin B should be avoided in this vulnerablepopulation. The data comparing fluconazole and conventional amphotericinB are limited, and those between fluconazole and lipid-based amphotericin Bare non-existent. Those data that do exist indicate that there is littledifference in outcome between conventional amphotericin B and fluconazole(33,34). One study indicates that treatment of fungal peritonitis may be lesseffective with fluconazole, but in that study relatively low doses offluconazole were used (35). Logic would suggest that as tissue penetration isvery good, fluconazole should be the agent of choice for penetrance of bodycavities (36). Not all agree, however (37).

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On the basis of the limited clinical infonnation that is currently available,either fluconazole or lipid-based amphotericin B can be used to treat a C.albicans bloodstream infection. Of course, the economic arguments favorfluconazole as the first line agent. If, however, the etiologic agent is aspecies other than C. albicans, the susceptibility profile of the isolate willdetennine the choice of agent. In the absence of MIC test results, cautionwould suggest erring towards a lipid-based amphotericin B.

MANAGEMENT OF CANDIDA INFECTION IN THEINTENSIVE CARE UNIT

The previous sections have highlighted the various arguments in favor andagainst the different drugs that are now available for the treatment ofCandida infections in the ICU. Application in clinical practice is usually lesswell circumscribed than in clinical theory. It is the purpose of this section todiscuss the treatment of fungal infection in the critically-ill patient. Asprevention is better than cure, the role of antifungal drug prophylaxis andother preventive measures will be considered first.

Prevention of fungal infection

This should encompass both therapeutic and other means of prevention offungal infection. In the immunocompromised patient, the immune system isineffective rendering the individual susceptible to fungal infection. In thecritically-ill patient, a whole host of problems, ofwhich immunocompromisemay be just one, may predispose the individual to fungal infection. Otherpredisposing factors may include upper gastrointestinal surgery oranastamotic breakdown. Frequently the underlying disease state or thedegree of debility of the patient are not factors that can be avoided orreversed. However, there are other elements of management which can bemodified and so reduce the likelihood of fungal infection. Behaviouralexamples include rigorous attention to the use of indwelling devices, such asintravenous cannulas, cautious and appropriate use of antibiotics, andprevention of overgrowth of gut fungi by trying to keep the bowelfunctional. These are all aspects of 'good house-keeping in the critically-ill,designed to reduce predisposition to fungal infection.In the ICU environment, cross-infection is an ever present, but avoidable,

hazard. There are several reports of clusters of infection in ICUs associatedwith contaminated transducers or intravenous fluids. There have beenepisodes of cross-infection, usually with C. albicans, although there are alsoreports of C. tropicalis and C. parapsilosis infections (38,39). Should this


involve an unusual fungus, the possibility of cross infection is very obvious.Molecular strain typing methods can be used to track transmission ofinfection as has been shown very clearly in the case of carriage of yeasts onthe hands of hospital staff.As with the prevention of infection in other areas, it is the complete

management package that is important and prevention is a very importantelement, especially in the critically-ill. Beyond common sense and goodhousekeeping are therapeutic intervention or prophylaxis. The role ofpharmacological prophylaxis is contentious in almost every area ofmedicine. Once again it is probably wise to usc the existing models ofneutropenic patients to examine the available evidence before trying to eitherextrapolate that information or to interpret the limited data available in thecritically-ill. In the neutropenic patient the concept behind prophylaxis hasbeen to reduce colonization of the gut. Reducing the gut reservoir has beenattempted with an ever increasing range of oral non-absorbable agents.These include polyenes, such as nystatin and amphotericin B, and azoles,such as clotrimazole, ketoconazole and itraconazole (40). Most of theavailable data suggest that almost all of these agents do reduce gutcolonization (41-46). The difficulty comes in interpreting whether this leadsto a reduction in Candida infection rates. Part of the problem is that Candidasepsis is relatively rare whilst colonization is common. Nevertheless, thereare a few studies in neutropenic patients, in liver transplant recipients, and inperitoneal dialysis patients that indicate a reduction in infection followingprophylaxis with nystatin, itraconazole, ketoconazole or fluconazole (47-51).From this limited information it may be inferred that there may be benefit incertain groups of patients. Even this conclusion is confounded by studieswhich describe significant breakthrough Candida infections in patients onprophylaxis (52). There are also other considerations. In these populationsprophylaxis is often aimed at fungi other than Candida species, e.g.Aspergillus species, and there appears to be little evidence to suggest thatanti-Aspergillus prophylaxis is effective (53).The other important, but largely theoretical, issue to consider is the

selection pressure exerted by any particular prophylactic agent to encouragethe emergence of resistant strains. This has been suggested by severalauthors (54-57). Safran and Dawson (54) demonstrated increased C.glabrata and C. parapsilosis when fluconazole was used prophylactically ina surgical lCU and suggested these infections were more difficult to treat.Most of these reports have been associated with fluconazole which mayreflect the popularity of this agent, rather than being a specific side-effect ofits use. The use of nystatin has been associated with the emergence of C.rugosa which is resistant to several polyenes, including amphotericin B (57).It is interesting that there are other studies which show no such trends (58).

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Ofgreater concern is the emergence of resistance to fluconazole. This hasbeen seen in persons with HIV infection where the major risk factors hasbeen seen to be regular and repeated exposure to azoles (5,28,55). Amongthe potential mechanisms that have been investigated are drug interactions.These patients may be on a large range of drugs some of which, such assulphadiazine and albendazole, may induce overexpression of the geneswhich encode efflux proteins (59).All these considerations are relevant in the critically-ill patient. Drug

pressures which alter the local flora place individuals at increased risk. Theemergence of resistant strains also complicates management and may maketreatment more difficult. If there were a way to measure them accuratelyboth mechanisms could in effect alter the attributable mortality fromCandida infection. Therefore caution must be exercised before advocatingprophylaxis. Conversely prevention is better than cure.The information available in the critically-ill is predictably sparse. In one

report, trauma patients in a surgical ICU treated with prophylacticfluconazole developed a significant number of episodes of sepsis due to C.glabrata and C. parapsilosis with an accompanying high mortality rate of44% (54). The authors suggest the emergence of these species wassecondary to fluconazole use. On a more positive note, prophylaxis withfluconazole in high-risk surgical patients has been reported to bring about areduction in both colonization and sepsis (60). This is a very important studybecause it suggests that prophylaxis should be used in specific groups ofcritically-ill patients where the risk of Candida sepsis is very high. However,it is hard to recommend this as a definitive approach on the basis of a singlepaper, but it certainly bears further examination.Other information comes from bums patients where nystatin has been

used prophylactically. Sheridan et al. (61) found no benefit in children,while Desai and Herndon (62) observed a reduction in both colonization andsepSIS.What conclusions can be drawn about prophylaxis? It may well be that in

specific high-risk situations in the critically-ill there is a theoretical benefit inusing prophylaxis as suggested by Eggiman et al. (60). At the veryminimum, further investigation is required. As with so many areas in criticalcare medicine, definitive evidence is still lacking (63).

It would be remiss to leave this subject without a briefmention of the gutand biotherapeutic agents. Early feeding and encouragement of gut mobilityand function are now standard in the management of the critically-ill. Theconcept of also using a natural agent to alter the ecosystem and provide anenvironment that encourages 'good bugs' and discourages nasty ones, suchas Candida species, is appealing. In animal studies various bacteria, such aslactobacilli and bifidobacteria which are present in yoghurt, have been


shown to influence the likelihood of Candida sepsis (64). Increasinghydrogen peroxide-producing lactobacilli can reduce vaginal candidiasis andjust eating yoghurt has been helpful in at least one study examining theincidence of vaginal candidiasis (65-68). This is an area that may bearfurther examination in the critically-iII, but at the present time is nothingmore than fanciful. Another area of research that has yet to have clinicalapplication is the oral administration of bovine anti-Candida antibodieswhich appears to reduce colonization (69).At present, it is my practice to give patients, who are likely to remain in

the ICU for a prolonged period, nystatin intra-orally and down thenasogastric tube. The rationale is not clearly evidence-based, but there aretwo potential benefits. The first is prevention of oral candidiasis which isunpleasant and uncomfortable for the patient and the second is thetheoretical benefit of a reduction in colonization of the upper gastrointestinaltract. The predominant organism in my unit, both in terms of colonizationand of infection is, and has been, C. albicans over the 15 years that thissimple regimen has been employed. There is an active policy for earlyfeeding and a tendency to use live yoghurt with the enteral feed. While thereis no evidence that these measures are of benefit, they do appear benign andare at least theoretically helpful in reducing colonization. To date, there havebeen no yoghurt-related infections.The policy in the unit in which I work is to use minimal antibiotics. We

prefer to use narrow-spectrum agents for short periods of time, based onactual culture results whenever possible. There is a deliberate policy ofavoiding broad-spectrum antibiotics and prolonged courses of treatmentwherever possible.

Treatment of fungal infection

Before discussing the treatment of Candida infection in the critically-iIIpatient, it is important to be clear that this an area that is evolving rapidly. Itis also important to be clear that as more information becomes available,some aspects of management are gradually acquiring an evidence base.However, significant elements of the approach to treatment are still uncertainand far from evidence-based. Parts of this discussion necessarily represent apersonal view.There are a number of important factors that must be taken into account

in deciding how to treat Candida infections in the critically-ill. These includethe prevalent organisms in the leu concerned and the risk status of thepatient requiring treatment (including factors such as time spent in the leuand the extent of fungal colonization). Each ICU has its own flora. In WestLondon, for example, there are several ICUs each with very different patient

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populations and among these units there is considerable variation in theprevalence of the different Candida species. Local knowledge is veryimportant in adapting the therapeutic approach to match local circumstances.In the ICU in which I work there is an active surveillance program so thatthere is information available about the organisms common in the unit andthe species colonizing individuals. Not all units seek to identify theirmicroflora so rigorously. However, it seems logical that early effectivediagnosis and treatment is dependent not only on a low threshold ofsuspicion that a Candida infection may be present, but also on an up-to-dateworking knowledge of the degree of colonization of 'at risk' patients.Rational drug treatment then depends on a knowledge of the type ofcolonization present. It is also important to know whether a particularorganism is typical for the unit, as an additional benefit of surveillance is theability to detect cross-infection. An example of this was the emergence of C.krusei colonizing three patients in my unit within a few days, when it had notbeen seen for months. Clearly, a surveillance program that identifies whichCandida species are most prevalent will influence the manner in whichtreatment is implemented. There is, of course, an obvious precedent inbacterial surveillance where organisms are identified to species level.

An obvious benefit of surveillance is its role in diagnosis. The definitivediagnosis of candidiasis is difficult and has often been made at a late stage.This situation has been improved by the observation that colonization oftenprecedes invasion and infection. If this is usually the case, then the detectionof colonization should be an integral part of early diagnosis. That thisassumption is correct has been confirmed by the fact that colonization andinfection are often caused by the same strain (70). Both heavy growth andmultiple sites of colonization are risk factors for the development ofinfection (61,71,72). There is now increasing and convincing evidence thatin high-risk septic patients with colonization, early treatment results in areduction in Candida sepsis.

MANAGEMENT OF CANDIDA SEPSIS

Because the most difficult part of the management of Candida sepsis is theinitial decision to treat, an approach that facilitates earlier recognition of thisdisease will make management easier and may improve outcome. In theICU, the 'triad' of Candida sepsis consists of a high-risk patient, thepresence of colonization at multiple sites, and the presence of a septicpicture. This pattern is associated with a very high probability of candidasepSIS.


It should be emphasized that this stratified and defined approach todiagnosis and treatment should not be confused with the 'what if diagnosticapproach. In this situation one or two elements of the triad are missing, but asuggestion has been made that the patient could have candidiasis and thatdiagnosis cannot be excluded. Here the focus is on exclusion rather thaninclusion. In other words, there is an irresistible urge to treat the patient onthe basis that the diagnosis cannot be excluded. This random intervention isoften termed empiric or pre-emptive treatment. Should the infection resolve,the decision to treat is interpreted as correct. Should it fail to resolve, thiswas not because the treatment was ineffective, but because the infection wasdue to another organism. The threshold for this treatment falls for futurecases because it is so effective. This used to be a common approach toantibiotic use in critical care where in the absence of an organism every 'bestguess' was seriously entertained. In most centers, however, this practice hasnow been abandoned.The rational management of patients with Candida sepsis demands that

patients at risk be identified and potential sites of colonization be screened. Itseems clear that an active surveillance program for high-risk patients is aprerequisite for early diagnosis and treatment. Furthermore, whencolonization is detected, the organisms involved should be identified andtheir susceptibility patterns determined in advance of the development ofsepsis. It may be prudent to alter the general management of these patientsby introducing measures to prevent or reduce Candida colonization. Theseinclude encouraging bowel motility and enteral feeding. Any patient who isseptic de novo should have their lines changed and this applies in bothbacterial and fungal sepsis.Conventionally, patients with positive blood cultures are a starting point

but as the current emphasis in management is on trying to make an earlierdiagnosis, waiting for a positive blood culture may not be appropriate. Highrisk patients with negative blood cultures will therefore be considered first.

High-risk patients with negative blood cultures

If the patient is clinically stable and non-septic, there should be continuedsurveillance for evidence of colonization. If the patient is clinically septic,then the number and nature of the colonized sites should be evaluated. Ifdeep sterile sites are positive, or if more than two sites (one of which is asterile site) are positive, then the patient has the 'triad of risk'. The triad iscolonization and sepsis in a high-risk patient. It is most inadvisable to awaita positive blood culture if the triad is present. Lines must be removed andaggressive treatment with antifungals should be commenced. The argumentsto support this approach have been discussed earlier.

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High-risk patients with bacterial sepsis, fungal colonizationand negative fungal blood cultures

A common scenario is that of a high-risk patient with clinical sepsis who hasmultiple sites colonized with Candida species, but also has a bacterialinfection. The bacterial infection may be the primary problem. Classically, inthe absence of positive fungal blood cultures, one way of assessing thecontributory role of Candida was failure to respond to specific antibacterialtreatment, but in a critically-ill patient the triad of Candida sepsis should bethe diagnostic threshold for initiating antifungals. Once again lines must beremoved or changed.

Patients with positive fungal blood cultures

In all patients with positive blood cultures the central lines should beremoved as a potential source of infection. In the study by Rex et al. (33)this accounted for a significant proportion of the positive cases. The speciesof Candida should be identified, and the patient should be evaluated. In aclinically septic patient with positive blood cultures there will be acombination of physical signs and laboratory indicators, such as elevatedwhite cell counts and CRP levels. There will be little doubt that the patient isseptic and the probability will be that this is fungal in origin. In the criticallyill it is very unusual to have Candida sepsis with no colonized sites. It ishighly unlikely that this scenario will arise without prior warning and inparticular without colonization. However, it is important to note that afeature of fungal infection is that other infections may be concurrent and thisshould be considered even if there is a primary infective diagnosis (73).If the organism is known then the treatment will be determined by the

species and the susceptibility pattern. In the absence of specific susceptibilitytest results, treatment can be commenced on the basis of the likelysusceptibility pattern, knowing the usual flora of the unit. Treatment maysubsequently be modified if the actual susceptibility pattern differs from thatanticipated. This approach of identifying the species and its likelysusceptibility pattern has a precedent in the management of bacterial sepsisand there is no reason not to use similar method with fungal infection.The potentially more difficult problem is that of the patient with positive

blood cultures who is clinically well. This has to be considered in the contextofwhether the patient is still at high risk or is in the recovery phase, whetherthey are colonized, and in the light of other factors, such as clinical signs andlaboratory markers. Once again the concept of the triad may be helpful: inthis instance one important part of the triad, sepsis, is missing. Managementis controversial, but removal of lines is essential. The approach to treatment


then poses a dilemma. Should antifungals be commenced in an otherwise fitindividual or not? This is contentious because the advocates for treatmentsuggest there is a possibility of late endophthalmitis or endocarditis.Documented instances of these complications usually follow confirmedcandidemia (74,75). The real issue is whether the microbiological resultindicates fungemia or contamination. Given that, on occasion, both positiveblood and catheter tip cultures can occur in the absence of clinical evidence,there is certainly an argument for a conservative approach. This approachwould defer treatment and await further culture results and evidence ofclinical infection. If, over the next 24 hours, there is no change in clinicalstate and further blood cultures are negative, there should, in my opinion, beno additional antifungal treatment. If the line is found to be colonized, thiswould reinforce this clinical approach. Each case requires individualconsideration.

Length of treatment

This is a difficult issue because there is little evidence to support anyparticular approach and much is based on anecdote and tradition. There areat least three elements to deciding when to stop treatment. The first isclinical resolution which in a critically-ill patient may be confounded byother nosocomial problems. The second is resolution of laboratorymeasurements such as inflammatory markers and negative cultures. Thethird relates to the site of the infection and local issues relating to treatmentand the likelihood of subclinical persistence of Candida which may thenrecrudesce when treatment is stopped (see below).In general terms, treatment should be discontinued when there is both

clinical resolution and the markers of infection have decreased and thisshould be supported by negative blood cultures and negative deep sitecultures. Superficial sites, such as the oropharynx and lower genital tract inwomen, may be more difficult to clear. It seems reasonable to use the sameapproach to clearance as with diagnosis and to look for a reduction incolonization of superficial sites. It would also seem reasonable to continuetreatment for a few days after resolution while cultures are confirmed asremaining negative (possibly 3-7 days).In many cases, there may be an obvious primary site of infection from

which the Candida sepsis originated. The site may be important in terms ofits ease of diagnosis, of treatment and clearance, and the likelihood ofrecrudescence. The specific sites at which Candida sepsis might be seatedwill be discussed below.

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MANAGEMENT OF CATHETER-RELATEDCANDIDEMIA

Chapter 8

Intravenous cannulas are common portals of entry and in debilitated patientsand in ICUs may be the most common single source of Candida sepsis.(76,77). In almost every study of candidemia in the critically-ill, line sepsishas been a major contributing factor (21,33,78,79). There is littleinformation about fungal blood cultures in clinically well patients, or theincidental discovery of a colonized line where sepsis is not present, both ofwhich occur in clinical practice. Classically, line infection is treated byremoval of the offending line and this has been shown, under somecircumstances, to reduce the duration of fungemia (78). On occasion,surgical removal of a thrombophlebitic vein may be necessary if there are nosigns of resolution on treatment (80,81). Once again, the major uncertaintiescenter on when to stop treatment in order to prevent dissemination fromoccurring. This problem is exemplified by one study of 57 venous catheterassociated candidemias (82). In that study, 26 patients became afebrilewithin 72 hours of catheter removal and therefore were not given antifungaltreatment. Endophthalmitis appeared later in four of these patients There isalso concern about late endocarditis (83).It is clearly difficult to determine the level of risk associated with isolated

catheter colonization as compared with systemic infection and there iscurrently inadequate information. What is clear is that changing the line inthe presence of infection is important and that any incidental finding ofcatheter colonization should be followed up.

MANAGEMENT OF CANDIDA ENDOCARDITIS

Fungal endocarditis is uncommon, but it is also very difficult to diagnose. Itmay be a primary presentation or a secondary nosocomial phenomenon.Only 50% ofproven cases of fungal endocarditis are associated with positiveblood cultures. Candida endocarditis is found in patients with abnormal orartificial valves, aortic and mitral, and also on the tricuspid valve in drugabusers. Autopsy findings suggest that in disseminated candidiasismyocardial involvement is common.Treatment depends on the presentation and the species. Surgery may be

indicated and is important in some cases if cure is to be achieved. LAB andABCD have been used successfully as has fluconazole (75,84,85). Candidaparapsilosis endocarditis has been treated with amphotericin Bandflucytosine (86). In children, a combination of amphotericin Bandfluconazole treatment has been successful (87). The real concern about


treatment is when has a cure been achieved. The efficacy of antifungalagents in an avascular vegetation is always questionable, blood cultures maybe unreliable and clinical signs may also be a poor guide. Sterile vegetationsmay linger so that even echocardiographic information may be unhelpful.The result is uncertainty and there are many reports of protracted treatmentand no clear guidelines as to how long a period of treatment is sufficient (8486).

MANAGEMENT OF URINARY TRACT CANDIDIASIS

Colonization of the urinary tract is very common in the critically-ill,especially if the patient has an indwelling urinary catheter or nephrostomies.Contamination of specimens is also common. There are no clear diagnosticcriteria (e.g. pyuria) for distinguishing colonization from infection, butcandiduria may be an early sign of Candida sepsis. Actual renal infection isusually a result of hematogenous spread and in these cases there is a veryhigh incidence of candiduria.

In localized infection or colonization of the bladder eradication ofCandida does not necessarily result in clinical benefit (88). The use ofamphotericin B washouts will certainly reduce colonization but techniqueand benefit are contentious (89,90). It has been suggested that if candiduriais present preoperatively, then fluconazole prophylaxis may reduce thelikelihood of systemic infection following surgery.Other renal tract complications from fungal infections include

emphysematous cystitis, especially in diabetics. An uncommon occurrence isformation ofa "fungus ball" leading to obstructive uropathy (91).

MANAGEMENT OF CANDIDA INFECTION OF THELIVER AND SPLEEN

This often remains undiagnosed and is usually detected by the presence ofsmall abscesses at autopsy. The reticuloendothelial system traps yeasts andso the liver and spleen can become the seat of infection. If there istranslocation across the gut wall then Candida is transferred to these sites viathe portal system. Both the liver and spleen should be amenable to therapybecause the lipid-based formulations of amphotericin B tend to accumulatein the reticuloendothelial system. Efficacy will be reflected by clinical andlaboratory markers as well as by radiological findings on CT scans orultrasound. Radiolucent lesions in the liver and spleen may be seen on CT.

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These may be multiple, non-enhancing, hypodense foci, 1-2 cm in diameter(92).

MANAGEMENT OF CANDIDA PERITONITIS

Candida in the peritoneum is a significant finding. The mechanism by whichit arrives there may be systemic spread or it may be consequent to intestinalspillage. As with any significant intra-peritoneal infection, adequatetreatment may require surgical intervention and washout of contaminatedfluid, especially if there is any suggestion that the cause is a leak. Althoughtranslocation almost certainly does occur, occult leakage should always beconsidered as a potential source of Candida species in the peritoneum. In astudy of 63 patients with candidemia, in 51 cases this had developedfollowing intra-peritoneal infection. There are two relatively consistentfeatures of peritoneal Candida infection. The first is that it is often part of amixed infection and the second is that it follows perforation of a viscus.Candida peritonitis should always be considered following a ruptured viscusif there is persistent fever. Surgical drainage is required in this situation, inthe same way that abscesses caused by more conventional organisms requireaggressive surgical treatment (93). Untreated, Candida peritonitis has amortality of 83%. In one study, no untreated patients with fungemia for morethan one day survived; autopsies revealed visceral microabscesses (94).

MANAGEMENT OF CANDIDA INFECTION OF THECENTRAL NERVOUS SYSTEM

This is very uncommon as a nosocomial occurrence in the critically-ill, butmay be seen in referred patients. There are several ways in which the centralnervous system can be involved, such as meningitis, cerebritis with micro- ormacro-abscesses, mycotic aneurysms, fungus balls and parenchymalbleeding.Meningitis can follow neurosurgery. Most patients who develop this

complication had recently received antibiotics and 50% had suffered fromantecedent bacterial meningitis. The cerebrospinal fluid shows a neutrophilicpleocytosis, indistinguishable from that of bacterial meningitis, and there areusually very low numbers of organisms present. The protein concentration israised and the glucose concentration reduced in about 30% of cases. Theoverall mortality of Candida meningitis is about 11%. Administration ofamphotericin B combined with flucytosine has been reported to be aneffective therapeutic approach (95). The azoles are also effective for central


nervous system infection, although most of the available data relate to othermycotic diseases (96-100).Brain abscess can occur and is difficult to diagnose, but should be

suspected in susceptible patients with no other source of infection andneurological signs. Multiple small abscesses may cause no localizing orlateralizing signs while large abscesses may produce focal signs. Candidaalbicans brain abscess has been associated with catheter-related fungemia(101).

MANAGEMENT OF CANDIDA ENDOPHTHALMITIS

This is a well-recognized problem following systemic infection in criticallyill patients. It is usually unilateral. Conscious patients complain of visualdisturbance with blurring pain and floaters, but in the critically-ill theinfection must be diagnosed by ophthalmoscopy When present, Candidaendophthalmitis is easily identified by the characteristic white exudates. Itshould always be sought in patients with a past history of drug abuse.The difficulty is the genuine likelihood of the problem after systemic

infection. In an autopsy study of 133 patients who died having had, but notnecessarily because of, severe fungal infection, 11 of the 24 patients whohad documented candidemia had ocular lesions (102). Other studies havereported a 28-37% incidence, although Donahue et al. (74) found few casesof Candida chorioretinitis and none of endophthalmitis in treated patients.While the prevalence of the problem is uncertain, this complication canoccur and so surveillance for eye problems should be part of routinemanagement.Treatment with fluconazole has been reported, and in non-neutropenic

patients 94% of cases resolved completely over about 6 weeks of treatment.In some cases vitrectomy was also performed (32). Treatment failure hasbeen reported with ABLC (103).

MANAGEMENT OF CANDIDA OSTEOMYELITIS

This is rare but has been documented in the critically-ill. It may besecondary to hematogenous spread or it may occur following injections intothe joint or surgery of the joint. It is more frequent in drug abusers where itmay occasionally affect unusual sites, such as vertebral and sternoclavicularinfection. Pain, persistent fever and radiologically characteristic osteolyticlesions are found. In the joints there are effusions from which Candida canbe isolated.

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In joints, arthritis is usually a complication of disseminated candidiasisbut can occur as a primary joint infection without spread from adjacentosteomyelitis. Treatment consisting of aspiration and parenteralamphotericin B has been documented to eradicate the joint infection withoutthe need for surgery. Bursectomy has, however, been required to eradicatebursal infection (104).The sternum can become infected following sternotomy. In these

situations the diagnosis, suggested by culture, should be confirmed bydemonstration of Candida pseudohyphae in debrided tissue. Confirmation ofCandida sternal osteomyelitis indicates the need for operative debridementand specific systemic antifungal therapy (105).

CONCLUSION

Fungal infection is a problem in the critically-ill patient and candidiasis isthe most common problem. This is a rapidly evolving subject withinteresting changes in diagnostic approaches and in the threshold fortherapeutic intervention. It is also an area where the range of available drugsis changing and therapeutic choices are diversifying. Unfortunately, fungalinfection is a rare problem in relative terms and because of this hardevidence to support different approaches to diagnosis and treatment remainslimited. There are no 'gold standards' , only conventional wisdom.Extrapolation from the immunocompromised patient is a poor surrogatebecause of the differences between the populations. This is particularlyrelevant because, as new approaches are tried, it is essential that evidence iscompiled to confirm or refute, the benefits of change. While this ishappening, the most important advance in the subject from a critical careperspective is a new higher level of awareness.

REFERENCES

I. Pfaller MA, Jones RN, Doern GV, et al. International surveillance of blood streaminfections due to Candida species in the European SENTRY Program: speciesdistribution and antifungal susceptibility including the investigational triazole andechinocandin agents. SENTRY Participant Group (Europe). Diagn Microbiol Infect Dis1999;35: 19-25.

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39. Romano F, Ribera G, Giuliano M. A study of a hospital cluster of systemic candidosisusing DNA typing methods. Epidemiol Infect 1994;112:393-8.


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46. Lumbreras C, Cuervas Mons V, et al. Randomized trial of fluconazole versus nystatinfor the prophylaxis of Candida infection following liver transplantation. I Infect Dis1996; 174:583-8.

47. van Burik IH, Leisenring W, Myerson D, et al. The effect of prophylactic fluconazole onthe clinical spectrum of fungal diseases in bone marrow transplant recipients with specialattention to hepatic candidiasis. An autopsy study of 355 patients. Medicine (Baltimore)1998;77:246-54.

48. Winston Dl, Pakrasi A, Busuttil RW. Prophylactic fluconazole in liver transplantrecipients. A randomized, double-blind, placebo-controlled trial. Ann Intern Med1999; 131:729-37.

49. Menichetti F, Del Favero A, Martino P, et al. Itraconazole oral solution as prophylaxisfor fungal infections in neutropenic patients with hematologic malignancies: arandomized, placebo-controlled, double-blind, multicenter trial. GIMEMA InfectionProgram. Gruppo Italiano Malattie Ematologiche dell' Adulto. Clin Infect Dis1999;28:250-5.

50. Siotman G, Burchard K. Ketoconazole prevents candida sepsis in critically ill surgicalpatients. Arch Surg 1987;122:147.

51. Lo WK., Chan CY, Cheng SW, Poon IF, Chan DT, Cheng IK. A prospective randomizedcontrol study of oral nystatin prophylaxis for Candida peritonitis complicatingcontinuous ambulatory peritoneal dialysis. Am 1 Kidney Dis 1996;28:549-52.

52. Meunier-Carpentier F, Kiehn TE, Armstrong D. Fungemia in the immunocompromisedhost. Changing patterns, antigenemia, high mortality. Am 1Med 1981 ;71 :363-70.

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54. Safran DB, Dawson E. The effect of empiric and prophylactic treatment with fluconazoleon yeast isolates in a surgical trauma intensive care unit. Arch-Surg 1997; 132: 1184-8.

55. Baily GG, Perry FM, Denning DW, Mandai BK. Fluconazole-resistant candidosis in anHIV cohort. AIDS 1994;8:787-92.

56. Gleason TG, May AK, Caparelli D, Farr BM, Sawyer RG. Emerging evidence ofselection of fluconazole-tolerant fungi in surgical intensive care units. Arch -Surg1997;132:1197-201.

57. Dube MP, Heseltine PN, Rinaldi MG, Evans S, Zawacki B. Fungemia and colonizationwith nystatin-resistant Candida rugosa in a bum unit. Clin Infect Dis 1994; 18:77-82.

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58. Kunova A, Trupl J, Spanik S, et al. Candida glabrata, Candida krusei, non-albicansCandida spp., and other fungal organisms in a sixty-bed national cancer center in 19891993: no association with the use of fluconazole. Chemotherapy 1995;41 :39-44.

59. Henry KW, Cruz MC, Katiyar SK, Edlind TO. Antagonism of azole activity againstCandida albicans following induction of multidrug resistance genes by selectedantimicrobial agents. Antimicrob Agents Chemother 1999;43: 1968-74.

60. Eggimann P, Francioli P, Bille J, et al. Fluconazole prophylaxis prevents intra-abdominalcandidiasis in high-risk surgical patients. Crit Care Med 1999;27: 1066-72.

61. Sheridan RL, Weber JM, Budkevich LG, Tompkins RG. Candidemia in the pediatricpatient with bums. J Bum Care RehabiI1995;16:440-3.

62. Desai MH, Herndon ON. Eradication of Candida burn wound septicemia in massivelyburned patients. J Trauma 1988;28: 140-5.

63. Lortholary 0, Dupont B. Antifungal prophylaxis during neutropenia andimmunodeficiency. Clin Microbiol Rev 1997;10:477-504.

64. Wagner RD, Pierson C, Warner T, et al. Biotherapeutic effects of probiotic bacteria oncandidiasis in immunodeficient mice. Infect Immun 1997;65:4165-72.

65. Elmer GW, Surawicz eM, McFarland LV. Biotherapeutic agents. A neglected modalityfor the treatment and prevention of selected intestinal and vaginal infections. JAMA1996;275:870-6.

66. Hillier SL, Krohn MA, Klebanoff SJ, Eschenbach DA. The relationship of hydrogenperoxide-producing lactobacilli to bacterial vaginosis and genital microflora in pregnantwomen. Obstet GynecoI1992;79:369-73.

67. Hilton E, Isenberg HD, Alperstein P, France K, Borenstein MT. Ingestion of yogurtcontaining Lactobacillus acidophi/us as prophylaxis for candidal vaginitis. Ann InternMed 1992;116:353-7.

68. Shalev E, Battino S, Weiner E, Colodner R, Keness Y. Ingestion of yogurt containingLactobacillus acidophi/us compared with pasteurized yogurt as prophylaxis for recurrentcandidal vaginitis and bacterial vaginosis. Arch Fam Med 1996;5:593-6.

69. Tollemar J, Gross N, Dolgiras N, Jarstrand C, Ringden 0, Hammarstrom L. Fungalprophylaxis by reduction of fungal colonization by oral administration of bovine antiCandida antibodies in bone marrow transplant recipients. Bone Marrow Transplant1999;23:283-90.

70. Pittet 0, Monod M, Filthuth I, Frenk E, Suter P, Auckenthaler R. Contour-clampedhomogenous electric field gel electrophoresis as a powerful epidemiological tool in yeastinfections. Am J Med 1991 ;91 :256s-263s.

71. Pittet 0, Monod M, Suter PM, Frenk E, Auckenthaler R. Candida colonization andsubsequent infections in critically ill surgical patients. Ann Surg 1994;220:751-8.

72. Neumann PR, Rakower SR. The risk of positive cultures for Candida in the critically illpatient. Crit Care Med 1978;6:73-6.

73. Verghese A, Prabhu K, Diamond RD, Sugar A. Synchronous bacterial and fungalsepticemia. A marker for the critically ill surgical patient. Am Surg 1988;54:276-83.

74. Donahue SP, Greven CM, Zuravleff 11, et al. Intraocular candidiasis in patients withcandidemia. Clinical implications derived from a prospective multicenter study.Ophthalmology 1994;101:1302-9.

75. Hogevik H, Alestig K. Fungal endocarditis--a report on seven cases and a brief review.Infection 1996;24: 17-21.

76. Komshian SV, Uwaydah AK, Sobel 10, Crane LR. Fungemia caused by Candida speciesand Torulopsis glabrata in the hospitalized patient: frequency, characteristics, andevaluation of factors influencing outcome. Rev Infect Dis 1989; II :379-90.


77. Lowder IN, Lazarus HM, Herzig RH. Bacteremias and fungemias in oncologic patientswith central venous catheters: changing spectrum of infection. Arch Intern Med1982; 142: 1456-9.

78. Rex JH, Bennett JE, Sugar AM, et al. Intravascular catheter exchange and duration ofcandidemia. NIAID Mycoses Study Group and the Candidemia Study Group. Clin InfectDis 1995;21 :994-6.

79. Sitges Serra A, Girvent M. Catheter-related bloodstream infections. World J Surg1999;23:589-95.

80. Benoit D, Decruyenaere J, Vandewoude K, et al. Management of candidalthrombophlebitis of the central veins: case report and review. Clin Infect Dis1998;26:393-7.

81. Hollingsed MJ, Morales JM, Roughneen PT, Burch KD. Surgical management ofcatheter tip thrombus: surgical therapy for right atrial thrombus and fungal endocarditis(Candida tropicalis) complicating paediatric sickle-cell disease. Perfusion 1997;12:197201.

82. Rose HD. Venous catheter-associated candidemia. Am J Med Sci 1978;275:265-9.83. Rubinstein E, Noriega ER, Simberkoff MS, Holzman R, Rahal JJ. Fungal endocarditis:

analysis of24 cases and review of the literature. Medicine (Baltimore) 1975;54:33 I-4.84. Nishida T, Mayumi H, Kawachi Y, et al. The efficacy of fluconazole in treating

prosthetic valve endocarditis caused by Candida glabrata: report of a case. Surg Today1994;24:651-4

85. Wells CJ, Leech GJ, Lever AM, Wansbrough Jones MH. Treatment of native valveCandida endocarditis with fluconazole. J Infect 1995;31 :233-5.

86. Darwazah A, Berg G, Faris B. Candida parapsilosis: an unusual organism causingprosthetic heart valve infective endocarditis. J Infect 1999;38: 130-1.

87. Aspesberro F, Beghetti M, Oberhansli I, Friedli B. Fungal endocarditis in critically illchildren. Eur J Pediatr 1999;158:275-80.


89. Fong IW. The value of a single amphotericin B bladder washout in candiduria. JAntimicrob Chemother 1995;36: 1067-71.

90. Sanford JP. The enigma of candiduria: evolution of bladder irrigation with amphotericinB for management - from anecdote to dogma and a lesson from Machiavelli. Clin InfectDis 1993;16:145-7.

91. Comiter CV, McDonald M, Minton J, Yalla SV. Fungal bezoar and bladder rupturesecondary to Candida tropicalis. Urology 1996;47:439-41.

92. Schmidt H, Fischedick AR, Peters PE, von Lengerke HJ. Candida abscesses in the liverand spleen. The sonographic and computed tomographic morphology. Dtsch MedWochenschr 1986;111:816-20.

93. Howell GP, Holt SD, Tiwari lB. Candida septicaemia and abscess formation followingmultiple injuries with blunt rupture of the stomach. J R Army Med Corps 1988;134:74-5.

94. Solornkin JS, Flohr AM, Simmons RL. Indications for therapy for fungemia inpostoperative patients. Arch Surg 1982; 117: 1272-5.

95. Nguyen MH, Yu VL. Meningitis caused by Candida species: an emerging problem inneurosurgical patients. Clin Infect Dis 1995;21 :323-7.

96. Bernard E, Carles M, Toussaint Gari M, Fournier JP, Dellamonica P. Value offluconazole in the treatment of systemic yeast infection. Patho1 BioI Paris 1989;37:690-3.

97. Foulds G, Brennan DR, Wajszczuk C, et al. Fluconazole penetration into cerebrospinalfluid in humans. J Clin Pharmacol 1988;28:363-6.

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98. Jones PD, Marriott D, Speed BR. Efficacy of fluconazole in cryptococcal meningitis.Diagn Microbiol Infect Dis 1989; 12:235s-238s.

99. Saag MS, Dismukes WE. Azole antifungal agents: emphasis on new triazoles.Antimicrob Agents Chemother 1988;32: 1-8.

100. Tucker RM, Williams PL, Arathoon EG, et al. Pharmacokinetics of fluconazole incerebrospinal fluid and serum in human coccidioidal meningitis. Antimicrob AgentsChemother 1988;32:369-73.

101. Burgert SJ, Classen DC, Burke JP, Blatter DD. Candidal brain abscess associated withvascular invasion: a devastating complication of vascular catheter-related candidemia.Clin Infect Dis 1995;21:202-5.

102. McDonnell PJ, McDonnell JM, Brown RH, Green WR. Ocular involvement in patientswith fungal infections. Ophthalmology 1985;92:706-9.

103. Virata SR, Kylstra JA, Brown JC, Wohl DA, Cohen MS. Worsening of endogenousCandida albicans endophthalmitis during therapy with intravenous lipid complexamphotericin B. Clin Infect Dis 1999;28: 1177-8.

104. Murray HW, Fialk MA, Roberts RB. Candida arthritis. A manifestation of disseminatedcandidiasis. Am J Med 1976;60:587-95.

105. Thomas FE, Martin CE, Fisher RD, Alford RH. Candida albicans infection of sternumand costal cartilages: combined operative treatment and drug therapy and 5fluorocytosine. Ann Thorac Surg 1977;23:163-6.

Chapter 9

Non-Candida Fungal Infections in the Intensive CareUnitNorth American Perspective

MARCOS I. RESTREPO and JOHN R. GRAYBILLUniversity ofTexas Health Science Center, San Antonio, Texas, USA

Infections caused by Candida species are the most common mycoticdiseases encountered in the intensive care unit (lCU), accounting for almost80% of the fungal infections among patients requiring critical care.However, an increasing number of other opportunistic fungal pathogens areencountered in these patients, including Aspergillus species, Cryptococcusneoformans, Fusarium species, Pneumocystis carinii, Scedosporium species,and the Zygomycetes. In addition, in many parts of the Americas, endemicfungal pathogens, such as Histoplasma capsulatum, Coccidioides immitis,and Blastomyces dermatitidis, that cause community-acquired infections,may be encountered among patients in intensive care.

FUSARIUM INFECTION

Fusarium species are prominent among the less frequent causes of seriousfungal infection in the ICU. The three most common species that causeinvasive human disease are F. solani, F. oxysporum and F. moniliforme, butat least 12 other species have also been implicated (1).

Mycology

Fusarium species are colorless (hyaline) moulds that adopt a septate hyphalform in tissue. They are common soil organisms and a number are importantplant pathogens. They have a worldwide distribution.

166

Epidemiology

Chapter 9

The most important factor influencing the outcome of Fusarium infection isthe predisposing condition of the host. Disseminated Fusarium infection ismost commonly encountered in neutropenic cancer patients (acute leukemia70-80% cases) and bone marrow transplant (BMT) recipients (2-6). Lessfrequently Fusarium infection is seen in other groups of immunosuppressedpatients including persons with AIDS, and severe burns patients (7). Themode of transmission is not well understood. There are several suggestedroutes of transmission, including inhalation, ingestion, implantationfollowing trauma, and acquisition via contaminated indwelling intravasculardevices (8,9).

Pathogenesis

Histopathologic examination of tissue lesions caused by Fusarium speciesreveals abscesses or nodular infarcts, similar to those seen in invasiveaspergillosis. Infarction is a consequence of hyphal vascular invasion andthrombotic occlusion. Hyphae are usually abundant in these lesions. Inaddition to tissue invasion, Fusarium species are important causes ofmycotoxicoses in animals and humans. These diseases are caused by theingestion of toxic fungal metabolites released when foods are stored underconditions that permit growth of infesting moulds.

Clinical course

The clinical manifestations of Fusarium infection vary depending the routeof infection and the nature of the host immune deficit. Fusarium species maycause a variety of focal infections including onychomycosis, keratitis,peritonitis (following chronic ambulatory peritoneal dialysis), andintravenous catheter-associated fungemia. Other sites that may be involvedin localized Fusarium infection include the nasal sinuses, skin, bones, joints,lungs, and brain.Disseminated Fusarium infection has similarities to disseminated

aspergillosis. It may be nosocomial in origin or community acquired;infections in hospitalized patients are often a result of colonization prior tohospital admission. For example, onychomycosis may be a benign primarysite from which the organism disseminates after cytotoxic chemotherapy foracute leukemia, a major risk factor for this infection (1). There have beenrelatively few reported cases of disseminated Fusarium infection beginningin patients in the ICU. Patients developing this disease have frequently beenon empiric, prophylactic or therapeutic antifungal medications thus

9. Non-Candida Fungal Infections in the Intensive Care Unit 167

reflecting the high resistance of Fusarium species to current antifungalagents. A frequent clinical presentation is a profoundly granulocytopeniccancer patient with a persistent fever, unresponsive to broad-spectrumantibiotics, and myalgias. Generalized skin lesions reflect hematogenousdissemination. Pneumonia, and sinusitis are also frequent. Skin lesionsinclude erythematous subcutaneous papules, painful erythematous maculesand papules, and target lesions (1,2,8,10). The course is often rapid and themortality may exceed 70%.

Diagnosis

The diagnosis requires the isolation of the fungus from clinical specimens,such as blood or material obtained from cutaneous lesions. Fusarium is theonly pathogenic mould which can be regularly recovered from thebloodstream. Fusarium species grow rapidly on Sabouraud's glucose agarbut usually do not sporulate on this medium. Their growth is often inhibitedby cycloheximide. Their affinity for small blood vessels may result in denseangioinvasion and associated thrombosis and distal infarction of tissue. Skinlesions may appear similar to ecthyma gangrenosum.. Fusarium speciesproduce specific antigens and may be identified by exoantigen test, but thereare no specific serodiagnostic tests available for these moulds.

Management

The most important factors influencing the outcome of Fusarium infectionare the underlying immunologic status of the patient and the extent of theinfection (1,11). Fusarium species are relatively to highly resistant toamphotericin Band triazole antifungal agents. In immune-compromisedpatients there are two main options for management: antifungal therapy andaugmentation of host defenses. Neither is easy or reliably effective.Antifungal therapy with amphotericin B remains the first option in

patients with Fusarium infection. Until recently, amphotericin B has been thebest agent, at least in terms of in-vitro antifungal activity (although MICvalues are often 1 Ilg/ml or higher) (1,11). The most effective dose is thehighest tolerable dose, usually 1.0-1.5 mglkg per day of amphotericin Bdesoxycholate. Because of rapid onset of renal failure, lipid-basedpresentations of amphotericin B have recently been used to deliver higherdoses (up to 15 mg/kg per dose); available preparations include liposomalamphotericin B (LAB, AmBisome) and amphotericin B lipid complex(ABLC, Abelcet) (2). In addition to reducing renal failure, in a large openstudy ofABLC, nine of 11 patients responded to this medication.

168 Chapter 9

Caspofungin and amphotericin B have shown synergistic activity in vitroagainst Fusarium species (12). The new triaz01es, voriconazole andposaconazole, have both shown useful in-vitro activity against Fusariumspecies. Posaconazole is also active in animal models (Rex, personalcommunication), and we have seen a dramatic response to treatment ofFusarium keratitis and iritis (Graybill, unpublished observations).Unpublished clinical reports support the use of both azoles, with responsesin more than 50% ofpatients.Immune reconstitution may be the most critical factor in the treatment of

Fusarium infection. Immunosuppressants and cytotoxic drugs should bereduced or eliminated. Abbreviating the duration of neutropenia may bedone with granulocyte colony-stimulating factors (granulocyte colonystimulating factor or granulocyte-macrophage colony-stimulating factor) (8).Reports thus far are anecdotal, and clinical benefit is unclear. There havealso been some unfortunate patients in whom recovery of neutrophils wasassociated with enlargement, necrosis, and hemorrhage of pulmonarylesions. Removal of indwelling intravascular catheters is also associated withclinical improvement if these are· the foci for fungemia (13). Overallmortality is variable from 50-80% of cases (2,4,6). Survival is uncommon ifneutropenia does not resolve.

Prevention

BMT patients are at high risk for Fusarium infection, but standard preventiveregimens are not established. Avoiding non-sterile water sources may be animportant factor in these patients (14).

SCEDOSPORIUM INFECTION

Two members of the genus Scedosporium have been implicated as causesof human disease. Scedosporium apiospermum (the current name for theasexual stage of the ascomycete mould, Pseudallescheria boydii) can infectboth immune-competent and immune-deficient patients (15,16). In otherwisehealthy individuals, percutaneous inoculation can produce the slowlyenlarging focal lesions of mycetoma. In neutropenic patients or thosereceiving corticosteroids, more rapidly advancing disease is manifested bypneumonia, sinusitis, endophthalmitis, orbital, or disseminated cutaneouslesions (17-19). In onco-hematologic patients receiving chemotherapy, afebrile course from onset to death may develop within days of neutropeniaand conclude within a few weeks.


The most critical clinical aspect of Scedosporium infection isidentification of the fungus, because in tissues the hyphae appear similar tothose of Aspergillus. However, most Aspergillus species (the exceptionbeing A. terreus) are susceptible to amphotericin B, while S. apiospermum ischaracteristically resistant (20). Unfortunately, despite being susceptible totriazoles in vitro, S. apiospermum is often clinically resistant to these agentsas well (21,22). Intravenously administered itraconazole has been used withsome success. However, scattered reports (mostly unpublished) stronglyfavor posaconazole or voriconazole (23). At the present time, based on littleinformation beyond in-vitro susceptibilities and a few case reports, we wouldrecommend voriconazole.

Scedosporium prolificans

This mould (which used to be named S. inflatum) has recently beenrecognized as a pathogen of immunocompromised hosts, particularly thosewith hematologic malignancies, such as acute leukemia (24-26). Little isknown about the natural reservoir or route of infection. However, thefrequent involvement of intravenous catheter sites and the frequency ofpneumonia suggest percutaneous or respiratory routes of infectionpredominate (27). The disease may commence shortly after the induction ofneutropenia. Dissemination to multiple organs, including the skin, brain,liver and spleen may occur (28). Scedosporium prolificans is resistant to allknown antifungal agents, and the only hope of response is resolution of theunderlying immune deficiency (29). In one reported series, nine of 10patients succumbed (27).

ZYGOMYCOSIS

Moulds of the Class Zygomycetes are second only to species ofAspergillusin causing disease in patients in intensive care. However, they areconsiderably less common than Aspergillus species, accounting for less than10% ofmould infections of immune-suppressed patients.

Mycology

The Zygomycetes have undergone multiple reclassifications since theirrecognition as human pathogens in the late 1800s. These moulds are dividedinto two Orders, termed the Mucorales and the Entomophthorales. Of these,the Mucorales account for almost all of the zygomycotic infections thatoccur in intensive care patients (30). Many different organisms have been

170 Chapter 9

implicated, but the genus Rhizopus is by far the most common cause ofhuman disease, most cases being caused by R. arrhizus. Other lessfrequently encountered human pathogens include Absidia corymbifera andMucor circinelloides (31). Despite the taxonomic distinctions, mostZygomycetes share many characteristics. They are generally rapid growerson nonselective media, and can fill a culture plate with mycelium in less than24 hours. However, they are rather fragile, perhaps because they are notseptate. Tissue specimens are often culture negative, despite the presence offungal elements on histopathology (30).

Pathogenesis

The Zygomycetes thrive in an acid environment, and high glucoseconcentrations also may stimulate growth. Thus, diabetics with ketoacidosisand patients receiving iron chelators are vulnerable (32,33). Leukocytes arekey to nonphagocytic killing of the mycelia, and metabolically impairedleukocytes, such as in diabetic ketoacidosis, steroid recipients, or bumpatients, as well as neutropenia itself, contribute to opening windows forexploitation by these fungi (34). Other predisposing factors include themetabolic acidosis and iron chelating agents used in patients onhemodialysis (35,36). The immune-competent patient rarely developsinfection with these organisms (37).

Clinical course

The clinical manifestations of zygomycosis vary depending on both the routeof infection and the nature of the host immune deficit. Cutaneous orsubcutaneous infection by trauma or inoculation of bum or wound sitesappears as a superficial black or gray overgrowth ofwounds, associated withprogressive necrosis of tissues. Nasal or sinus infection is most commonlyseen in diabetic ketoacidosis, and accounts for one third to one half ofpatients with zygomycosis (38). The Zygomycetes are angioinvasive, andtheir weaving mycelial thrombi frequently produce necrosis and distalischemic tissue infarction. In this they are reminiscent of acute invasiveaspergillosis. Invasion from the sinuses may perforate through the palate orextend into the orbit, and spread along blood vessels or nerves to the brain(37-40). In patients with leukemia and severe neutropenia, the Zygomycetescommonly produce a rapidly progressive necrotizing pneumonia, again withvascular involvement and infarction like aspergillosis, and again with ahighly lethal outcome (34,41).Although zygomycosis is commonly acquired outside of the hospital, in

neutropenic patients the infection may be acquired nosocomially. However


the infection is acquired, progression is commonly rapid, and most patientsshortly end up in the ICU.

Diagnosis

The clinical setting is the key to diagnosis of zygomycosis. The patient withketoacidosis, hemodialysis, or neutropenia who develops aggressivesinusitis, an orbital mass, loss of sense of smell, facial numbness, or facialnerve paralysis should be suspected, as should the person with wedge-shapedpulmonary infiltrates typical of the syndrome of pulmonary infarction(34,41). Black discolored bum and wound sites are also of concern. This isespecially so in the neutropenic thrombocytopenic patient. The diagnosis ofzygomycosis should not be difficult if one appreciates that the rapid spreadand high mortality of these infections requires prompt aggressive tissuebiopsy whatever the underlying disease of the patient. Even though theseorganisms are vasculotropic, they are virtually never cultured from the bloodand secretions, such as sputum, are not highly reliable.Unlike aspergillosis, there are no serologic tests for zygomycosis.

Diagnosis depends on histopathology and culture confirmation. Aggressivesurgical or bronchoscopic biopsy should be undertaken. Zygomycete hyphaediffer from those of Aspergillus in that they are broader, not usually septate,branch at irregular angles, and may be readily seen in hematoxylin/eosinstained preparations. Silver staining is usually not required. At least sometissue specimens should be sent for culture; homogenization and macerationshould be avoided to facilitate isolation. Identification of the speciesinvolved may become more important in the future as treatment options areexpanding. Kontoyannis et al. (42) have recently modified the diagnosticcriteria for zygomycosis to resemble those for invasive aspergillosis. Bycombining clinical and laboratory findings, it is possible to make aconfirmed (clinical findings plus positive tissue histopathology/culture) orprobable diagnosis (clinical findings plus positive sputum/bronchoalveolarlavage culture) determination.

Management

Once a diagnosis of zygomycosis has been made, treatment must beextremely prompt and extremely aggressive. There are three components ofsuccessful management. The first is surgical resection. Superficial infectionand sino-orbital infection should be debrided vigorously back to freelybleeding tissue, and clean margins confirmed (34,43,44). Delay of just a fewhours may permit the hyphae to track along nerves or blood vessels into thecavernous sinus, or into the brain. Focal pulmonary lesions should be

172 Chapter 9

resected if possible, but this may be very difficult. Debridement may need tobe repeated multiple times until a patient is stabilized.The second component is correcting the underlying predisposing factor.

Immunosuppressants and cytotoxic drugs should be reduced or eliminatedrapidly. Steroids should be rapidly tapered. Correction of ketoacidosis andhyperglycemia is critical. Deferroxamine or other iron chelators should bestopped. Correction of neutropenia with granulocyte colony-stimulatingfactor would seem to be desirable, but it remains unclear whether thisimproves outcome. Some have argued that hyperbaric oxygen improvesperfusion of infected ischemic areas and allows phagocytes to function moreeffectively (45). The clinical benefit is unclear. It is not possible tooveremphasize the importance of correcting predisposing factors.The third component of successful management is antifungal therapy.

Treatment of zygomycosis has been limited by: (a) the frequent necrosis ofinfected tissues, which impairs antifungal drug penetration; (b) the poorpenetration of amphotericin B into the brain in general; and (c) the relativerefractoriness of these organisms to available antifungal agents.Amphotericin B remains the mainstay of therapy. Because mortalitycommonly exceeds 50%, the most effective dose of amphotericin B mayloosely be defined as the largest dose that can be given (34). Somephysicians have given doses as high as 15 mg/kg per day of LAB and wehave used similar doses of ABLC (46-48). There is dramatically reducednephrotoxicity with lipid formulations of amphotericin B, and these drugscan be administered for many months with few adverse sequelae. Casereports indicate the clinical efficacy of lipid forms of amphotericin B, butthere is no clear evidence of their superiority to amphotericin Bdesoxycholate. In addition to intravenous administration, some have usedamphotericin B-soaked packing in wounds (50 mg per liter of water; salineshould not be used). The outcome of zygomycosis is commonly resolved forgood or bad within a week of initiating therapy. Total doses of amphotericinB have ranged from 1.5-2.5 grams, but the key part of treatment is gettingthe process under initial control.

In general, the azoles have been disparaged as treatment for zygomycosis(49). However, some isolates of Absidia species are susceptible toitraconazole in vitro, and there have been rare cures with itraconazoletherapy. Other studies have found most Zygomycetes highly resistant tovoriconazole (50). A new triazole, posaconazole, has shown broad potencyagainst most Zygomycetes tested, including Rhizopus and Absidia species,which together account for most human infections (51). In ongoing studies,we have found that posaconazole is highly effective in neutropenic miceinfected with Mucor. Mice failed treatment with itraconazole, despite theorganism being susceptible in vitro (Graybill, unpublished observations).


Finally, there is a small successful clinical experience with posaconazole forzygomycosis (Graybill, unpublished observations). The dose ofposaconazole is 200 mg of oral solution given four times daily with a fattyfood.

TRICHOSPORONOSIS

Trichosporon asahii (formerly T. beigelii) is the cause of white piedra, asuperficial hair shaft infection. However, in severely immune-depressedpatients T. asahii can occasionally cause fungemia, pneumonia, and widelydisseminated infection (52). If the three morphologic forms of the fungus(blastoconidia, arthroconidia, and hyphae) are present in tissue the diagnosisof trichosporonosis may be made. The organism is easily recovered fromblood, urine, and tissue. Once isolated, it can be identified by standardbiochemical tests (53). Like Candida species, T. asahii can colonize thegastrointestinal tract and can invade through the mucosa (54,55). Infectionwith T. asahii may cause a false positive test result for cryptococcal antigen(56).Profound neutropenia strongly predisposes toward infection, which may

develop earlier than aspergillosis (57,58). Fever commonly marks the onsetof disease. Skin involvement occurs in up to two thirds of patients; thelesions evolve from maculopapules to necrotizing ulcers or hemorrhagicbullae (59-61). Pneumonia is characterized by nodular or diffuse infiltrates.Other organs may also be involved (62).A combination of amphotericin B (1.0-1.5 mg/kg per day) plus

flucytosine (50-100 mg/kg per day) has been used with some success, butthere have been reports of amphotericin B treatment failure. In-vitro testingshows the organism is susceptible to amphotericin B, with MIC values of<0.5 ~g/ml (60). Fluconazole and the broad-spectrum triazoles have beeneffective both in vitro and in rabbits and mice (63,64). It is not clear whetherfluconazole or the broad-spectrum triazoles are superior. Both fluconazoleand itraconazole have been used successfully clinically. Fluconazole has hadan initial advantage because it is available intravenously, and is extremelywell tolerated.

ENDEMIC MYCOSES

These are also termed the dimorphic mycoses, because the organisms have afree-living mould form in the environment, produce conidia which infect byinhalation, and then convert to yeast-like forms in the lungs. Infection

174 Chapter 9

disseminates hematogenously, but usually resolves with no sequelae, underthe control of cell-mediated immunity. There are five endemic mycoses.Histoplasmosis, coccidioidomycosis, blastomycosis, and paracoccidioidomycosis are all endemic to the Americas, while Penicillium marnefJeiinfection is found in Southeast Asia (65-68).None of these infections is nosocomial in origin, but they regularly

appear in ICU patients. The usual setting is in the patient with suppressedcell-mediated immunity. The predominant presentation is diffuse pulmonarydisease, commonly like miliary tuberculosis, although very aggressive focalpulmonary disease may also occur. Mucosal and cutaneous lesions andmeningitis may also be present. The patient with lymphoma, chronic steroidtherapy, or AIDS is most vulnerable. The disease may be primary, occurringa few weeks following infection, or it may be due to resurgence of aninfection acquired many years earlier. Travel histories often help to explainthe appearance of these organisms far from their natural range. Thediagnosis is made by histopathology of biopsies of lung or other involvedtissue, or bronchoalveolar lavage. Cultures may require three or more weeksto tum positive; time which the patient rarely. has. Histoplasmosis may alsobe diagnosed by Wright-Giemsa stain of blood smears (especially in patientswith HIV infection) or by a highly sensitive and specific ELISA test forantigen (69).The patient presenting with a fulminating endemic mycosis is frequently

hypoxic, and may require intubation (70,71). The most rapidly actingantifungal available is amphotericin B, and this should be commenced atdoses up to 1 mg/kg per day. If other nephrotoxic agents are being givenconcurrently, ABLC or LAB, at a dose of 5 mglkg per day, can besubstituted (72). When the patient has significantly improved, usually withina few weeks, treatment can be changed to long-term maintenance withitraconazole or fluconazole (73-75). Length of treatment depends on theunderlying conditions, but is usually 6 months for otherwise uncomplicatedpatients.

CRYPTOCOCCOSIS

Cryptococcus neoformans is an encapsulated pathogenic yeast with aworldwide distribution. Although C. neoformans can cause severepneumonia, the manifestation that usually prompts admission to the ICU isneurologic dysfunction from meningitis. Diagnosis is made by positive IndiaInk smear of the cerebrospinal fluid (CSF), or measurement of cryptococcalantigen titer, or growth of C neoformans from CSF. The CSF is commonlyhypoglycorrachic in patients with an underlying neoplasm and those


receiving corticosteroid therapy, but usually is normal (other than highfungal burden) in persons with AIDS. Neurologic dysfunction includesmeningismus, impaired mentation, and cranial neuropathies, which arecommonly manifestations of high CSF pressure, usually caused bycommunicating hydrocephalus. In one study of about 400 AIDS patientswith cryptococcal meningitis, the mean pretreatment opening pressure was25 cm water, and one fourth of the patients had opening pressures above 35cm water (76). In AIDS patients, steroids are not recommended for high CSFpressure, but mannitol may be given. After excluding obstructivehydrocephalus, the pressure is reduced by direct lumbar puncture with alarge bore needle, and withdrawal of sufficient fluid to drop the pressure to<20 cm water. This may need to be repeated on a daily basis for more than aweek, but it can be stopped when a follow-up opening pressure is normal.Occasionally, lumbar drains or ventriculo-peritoneal shunts may be used.Antifungal treatment is accomplished with amphotericin B, at a dose 0.6mg/kg for 2 weeks (outcome is probably improved by adding flucytosine at adose of25 mg/kg every 6 hours), followed by long-term fluconazole therapy(77).

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17. Bernstein EF, Schuster MG, Stieritz DO, Heuman PC, Uitto J. Disseminated cutaneousPseudallescheria boydU. Br 1 Dermatol 1995;132:456-60.

18. Ksiazek SM, Morris DA, Mandelbaum S, Rosenbaum PS. Fungal panophthalmitissecondary to Scedosporium apiospermum (Pseudallescheria boydii) keratitis. Am 1Ophthalmol 1994;118:531-3.

19. McKelvie PA, Wong EY, Chow LP, Hall AJ. Scedosporium endophthalmitis: two fatalcases of Scedosporium infection presenting with endophthalmitis. Clin Exp Opththalmol2001 ;29:330-4.

20. Walsh TJ, Peter 1, McGough DA, et al. Activities of amphotericin B and antifungalazoles alone and in combination against Pseudallescheria boydii. Antimicrob AgentsChemother 1995;39: 1361-4.

21. Galgiani IN, Stevens DA, Graybill lR, et at. Pseudallescheria boydii infections treatedwith ketoconazole. Chest 1986;86:219-24.

22. Goldberg SL, Geha 01, Marshall WF, Inwards 01, Hoagland He. Successful treatmentof simultaneous pulmonary Pseudallescheria boydii and Aspergillus terreus infectionwith oral itraconazole. Clin Infect Dis 1993;16:803-5.

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24. Scedosporium proliflcans Study Group. Deep infections caused by Scedosporiumproliflcans. A report on 16 cases in Spain and a review of the literature. Medicine(Baltimore) 1997;76:256-65.

25. Wilson CM, O'Rourke El, McGinnis MR, Salkin IF. Scedosporium inflatum: clinicalspectrum of a newly recognized pathogen. 1 Infect Dis 1990; 161: 102-7.

26. Lopez L, Gasztelurritia L,Cuenca-Estrella M, et al. Infection and colonization byScedosporium proliflcans. Enfermedades Infecciosas y Microbiologia Clinica200 I; 19:308-13.

27. Tapia M, Richard C, Baro 1, et al. Scedosporium inflatum infection inimmunocompromised haematological patients. Sr 1 Haematol 1994;87:212-4.

28. Wood GM, McCormack lG, Muir DB, et al. Clinical features of human infection withScedosporium inflatum. Clin Infect Dis 1992;14:1027-33.

29. Espinel-Ingroff A. Comparison of the in vitro activities of the new triazole SCH56592and the echinocandins MK-0991 (L743,872) and LY303366 against opportunisticfilamentous and dimorphic fungi and yeasts. 1 Clin Microbiol 1998;36:2950-6.

30. Ribes lA, Vanover-Sams CL, Baker OJ. Zygomycetes in human disease. Clin MicrobiolRev 2000;13:236-301.


31. Scholer HJ, Muller E, Schipper AA. Mucorales. In: Fungi Pathogenic for Humans andAnimals. Howard DH, ed. New York: Marcel Dekker; 1983:9-59.

32. Waldorf AR, Ruderman N, Diamond RD. Specific susceptibility to mucormycosis inmurine diabetes and bronchoalveolar macrophage defense against Rhizopus. J ClinInvest 1984;74: 150-60.

33. Reinhardt D, Kaplan W, Ajello L. Experimental zygomycosis in alloxan-diabetic rabbits.Infect Immun 1970;2:404-13.

34. Tedder M, Spratt JA, Anstadt MP, et al. Pulmonary mucormycosis. Ann Thorac Surg.1994;57: 1044-50.

35. Boelaert JR, van Cutsem J, de Locht M, Schneider YJ, Crichton RR. Deferoxamineaugments growth and pathogenicity of Rhizopus, while hydroxyopyridine chelators haveno effect. Kidney Int 1994;45:667-71.

36. van Cutsem J, Boelaert JR. Effects of deferoxamine, ferrioxamine, and iron inexperimental mucormycosis (zygomycosis). Kidney Int 1989;36: 1061-8.

37. Meyers BR, Wormser GP, Hurst SF, Blitzer A. Rhinocerebral mucormycosis: premortem diagnosis and therapy. Arch Intern Med 1979; 139:557-60.

38. Pillsbury HC, Fischer ND. Rhinocerebral mucormycosis. Arch Otolaryngol2000; 103:600-4.

39. Blitzer A, Lawson W, Meyers BR, Biller HF. Patient survival factors in paranasal sinusmucormycosis. Laryngoscope 1980;90:635-48.

40. Sohail MA, AI Khabori M, Hyder J, Verma A. Acute fulminant fungal sinusitis: clinicalpresentation, radiological findings and treatment. Acta Tropica 2001 ;80: 177-85.

41. Straatsma BR, Zimmerman LE, Gass JDM. Phycomycosis: a clinical pathologic study offifty-one cases. Lab Invest 1962; 11 :963-85.

42. Kontoyiannis DP, Wessel VC, Bodey GP, Rolston KVI. Zygomycosis in the 1990s in atertiary-care cancer center. Clin Infect Dis 2000;30: 85 1-6.

43. Rinaldi MG. Zygomycosis. Infect Dis Clin North Am 1989;3: 19-42.44. Anaissie EJ, Bodey GP, Rinaldi MG. Emerging fungal pathogens. Eur J Clin Microbiol

Infect Dis 1989;8:323-30.45. Ferguson BJ, Mitchell TG, Moon R, Camporesi EM, Farmer 1. Adjuvant hyperbaric

oxygen treatment of rhinocerebral mucormycosis. Rev Infect Dis 1988;10:551-9.46. Walsh TJ, Hiemenz JW, Seibel NL, et al. Amphotericin B lipid complex for invasive

fungal infections: analysis of safety and efficacy in 556 cases. Clin Infect Dis1998;26: 1383-96.

47. Gonzalez CE, Couriel DR, Walsh T1. Disseminated zygomycosis in a neutropenicpatient: successful treatment with amphotericin B lipid complex and granulocyte colonystimulating factor. Clin Infect Dis 1997;24: 192-6.

48. Herbrecht R, Letscher-Bru V, Bowden RA, et al. Treatment of 21 cases of invasivemucormycosis with amphotericin B colloidal dispersion. Eur J Clin Microbiol Infect Dis2001;20:460-6.

49. Terrell CL. Antifungal agents II. The azoles. Mayo Clin Proc 1999;74:78-100.50. Dannaoui E, Meis JFG, Mouton JW, Verweij PE. Evaluation of combinations of

antifungal agents against zygomycetes. In: Abstracts of the 40th Interscience Conferenceon Antimicrobial Agents and Chemotherapy, 2000;abstract 934,p.368.

51. Dannaoui E, Meletiadis J, Meis J, Mouton JW, Verweij PE. In vitro activity ofconventional and new antifungals against zygomycetes. In: Abstracts of the 40th

Interscience Conference on Antimicrobial Agents and Chemotherapy, 2000;abstract 939,p.370.

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52. Fisher DJ, Christy C, Spafford P, et ai. Neonatal Trichosporon beigelii infection: reportofa cluster of cases in a neonatal intensive care unit. Pediatr Infect Dis J 1993;12:14955.

53. Gueho E, Faergemann J, Lyman C, Anaissie EJ. Malassezia and Trichosporon: twoemerging pathogenic basidiomycetous yeast-like fungi. J Med Vet Mycol 1994;32,suppl. 1:367-78.

54. Walsh TJ, Pizzo PA. Nosocomial fungal infections. Ann Rev Microbiol 1988;42:517-45.55. Walsh TJ. Trichosporonosis. Infect Dis Clin North Am 1989;3:43-51.56. Melcher GP, Rinaldi MG, Lee JW, Pizzo P, Walsh T. Demonstration of a cell wall

antigen cross-reacting with cryptococcal polysaccharide in experimental disseminatedtrichosporonosis. J Clin Microbiol 1991 ;29: 192-6.

57. Lyman CA, Garrett KF, Pizzo PA, Walsh TJ. Response of human polymorphonuclearleukocytes and monocytes to Trichosporon beigelii: Host defense against an emergingopportunistic pathogen. J Infect Dis 1994;170: 1557-65.

58. Muranaka H, Suga M, Nakagawa K, et ai. Effects of granulocyte and granulocytemacrophage colony-stimulating factors in a neutropenic murine model oftrichosporonosis. Infect Immun 1997;65:3422-9.

59. Hoy J, Hsu KC, Rolston K, Hopfer RL, Bodey GP. Trichosporon beigelii infection: areview. Rev Infect Dis 1986;8:959-67.

60. Walsh TJ, Melcher GP, Rinaldi MG, et al. Trichosporon beigelii, an emerging pathogenresistant to amphotericin B. J Clin Microbiol 1990;28: 1616-22.

61. Anaissie EJ, Bodey GP, Kantarjian H, Ro J, Vartivarian SE. New spectrum of fungalinfections in patients with cancer. Rev Infect Dis 1989; II :369-78.

62. Walsh TJ, Newman KR, Moody M, Wharton RC, Wade Jc. Trichosporonosis in patientswith neoplastic disease. Medicine (Baltimore) 1986;65:268-79.

63. Anaissie EJ, Hachem R, Karyotakis NC, et ai. Comparative efficacies of amphotericin B,triazoles, and combination of both as experimental therapy for murine trichosporonosis.Antimicrob Agents Chemother 1994;38:2541-4.

64. Anaissie EJ, Gokaslan A, Hachem R, et at. Azole therapy for trichosporonosis: clinicalevaluation of eight patients, experimental therapy for murine infection, and review. ClinInfect Dis 1992;15:781-7.

65. Bradsher RW. Blastomycosis. Clin Infect Dis 1992;14, Suppl. I :S82-S90.66. Wheat LJ, Connolly-Springfield PA, Baker RL, et ai. Disseminated histoplasmosis in the

acquired immune deficiency syndrome: clinical findings, diagnosis and treatment, andreview of the literature. Medicine (Baltimore) 1990;69:361-74.

67. Fish DG, Ampel NM, Galgiani IN, et ai. Coccidioidomycosis during humanimmunodeficiency virus infection. A review of 77 patients. Medicine (Baltimore)1990;69:384-91.

68. Brummer E, Castaneda E, Restrepo A. Paracoccidioidomycosis: an update. ClinMicrobiol Rev 1993;6:89-117.

69. Williams B, Fojtasek M, Connolly-Stringfield P, Wheat J. Diagnosis of histoplasmosisby antigen detection during an outbreak in Indianapolis, Ind. Arch Pathol Lab Med1994;118:1205-8.

70. Arsura EL, Bellinghausen PL, Kilgore WB, et aI., Septic shock in coccidioidomycosis.Crit Care Med 1998;26:62-5.

71. Booker KJ. Blastomycosis-induced respiratory failure: the successful application ofcontinuous positive airway pressure. Heart Lung 1996;25:384-7.

72. Wong-Beringer A, Jacobs R, Guglielmo BJ. Lipid formulations of amphotericin B:clinical efficacy and toxicities. Clin Infect Dis 1998;27:603-18.


73. Wheat J, Hafner R, Korzun AH, et al. Itraconazole treatment of disseminatedhistoplasmosis in patients with the acquired immunodeficiency syndrome. Am J Med1995;98:336-42.

74. Catanzaro A, Galgiani IN, Levine BE, et al. Fluconazole in the treatment of chronicpulmonary and nonmeningeal disseminated coccidioidomycosis. Am J Med1995;98:249-56.

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77. Van der Horst C, Saag M, Cloud G, et al. Treatment of cryptococcal meningitisassociated with the acquired immunodeficiency syndrome. N Engl J Med 1997;337:1521.

Chapter 10

Non-Candida Fungal Infections in the Intensive CareUnitEuropean Perspective

HILARY HUMPHREYSRoyal College o/Surgeons in Ireland and Beaumont Hospital, Dublin, Ireland

Infections caused by Candida species are the commonest mycological causesof infection in the intensive care unit (lCU). However non-Candida fungalinfections are increasingly seen as either a presenting cause for ICUadmission or following nosocomial acquisition in a critically-ill patient.Most are relatively episodic. Pneumocystis carinii pneumonia (PCP) is oftenassociated with AIDS, and aspergillosis is usually confined toimmunocompromised patients although outbreaks can occur within the ICU.Cryptococcosis is an infrequent infection in Western Europe and otherendemic fungal infections, such as histoplasmosis and coccidioidomycosis,occur rarely following overseas travel.

PNEUMOCYSTIS CARINII INFECTION

Mycology

It is over eighty years since the discovery of this organism, which wasclassified as a protozoan for many years. This was partly because of itsappearance, which resembles protozoan cysts, and also because it respondsto drugs that are active against protozoa. In the late 1980s the geneticsequence of P. carinii was determined and because this was more fungalthan protozoan, P carinii was reclassified as a fungus (1).Fungus-like features include the cyst form of P. carinii, the fungal-type

asci, the presence of lamellar cristae in the mitochondria and the absence ofhighly visible organelles. However, it is an unusual fungus in that it refuses

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to grow continuously in vitro and is resistant to classical antifungal agents,due to the absence of ergosterol in the cell membrane. Furthermore, unlikemost fungi, the trophic form has a fragile cell wall. rRNA sequenceinformation places the genus in its own branch between the Ascomycota andthe Basidiomycota (l). Although this fungus is found in many different hostsor animals, strains are host-specific so that humans are unlikely to beinfected by, for example, rat P. carinii (2).

Epidemiology

Apart from persons with HIV infection and other severelyimmunosuppressed patients, infection with P. carinii is unusual. However, itremains an AIDS-defining illness in HIV-positive patients. In the 1980s andearly 1990s, patients with PCP were often not admitted to the ICU because itwas believed that the invariably poor outcome could not justify the level ofcare. However, with improvements in the management of HIV infectionincluding highly active anti-retroviral therapy (HAART) and improvementsin critical care, more patients are being admitted to the ICU for initialmanagement of PCP followed by discharge to other wards and then to thecommunity.

In addition to conventional pathogens, such as the pneumococcus, PCP isone of the commonest causes of respiratory illness in HIV-positive patients.In one study, it was the cause of pulmonary infiltrates in 67% of HIVpositive patients (3). Among HIV-positive patients admitted to the ICU, PCPis the commonest admitting diagnosis accounting for approximately 36% ofcases (4). Many of these patients require ventilation. The mortality variesdepending upon the severity of presentation and the CD4 cell count, but theoverall three-month mortality is about 33% (5,6). Admission to ICU and theoutcome of patients admitted there will vary according to the patientpopulation and the expertise available locally. Hospitals inexperienced in themanagement of patients with PCP are more likely to admit patients with PCPto the ICU, but survival is lower in such hospitals (7,8).

Clinical course

The clinical presentation of PCP is similar to that of many other causes oflower respiratory tract infection, including bacterial pneumonia. Cough,often non-productive, breathlessness and fever are characteristic features.The chest radiograph in early infection may be normal and the classicalappearances of bilateral perihilar interstitial infiltrates that progress todiffuse confluent alveolar shadowing, are not always present (2). In a patientwho is HIV-positive, this presentation should immediately suggest a


diagnosis of PCP in the absence of laboratory confinnation. The CD4 cellcount within 2 weeks of admission, and the APACHE II or similar clinicalevaluation score, help predict outcome (9,10). In one study, those patientswith CD4 counts >100 per mm3 had a 25% mortality compared to 100%mortality in those with a count of <10 per mm3 (9).

Diagnosis

The diagnosis of PCP should be seen against a background of theinvestigation of the immunocompromised or HIV-positive patient withrespiratory infection (10). Other causes of infection should be considered,including legionellosis, cytomegalovirus infection, tuberculosis, etc.Although bronchoscopy to obtain a specimen either by brush or lavage isoften recommended, sputum induction using hypertonic saline has replacedbronchoscopy as the initial diagnostic procedure (11). Furthennore, manypatients if particularly ill at presentation may not tolerate bronchoscopy.Conventional laboratory approaches following the receipt of an appropriaterespiratory sample include toluidine or methenamine silver stains, whichstain cysts. However, immunofluorescent stains using monoclonalantibodies, have a higher sensitivity and have in many centers replacedconventional stains. Although polymerase chain reaction (PCR)-basedmethods are only available in some research or referral centers, it is possiblethat these procedures may become the diagnostic tool of choice in the nearfuture, due to their increased sensitivity and their potential for use inpartially treated patients. Furthennore, this technology facilitates typing ofstrains and the investigation of outbreaks. Compared withimmunofluorescence, the sensitivity and specificity of PCR for lavagespecimens is 100% and 98% respectively (12). With the use of inducedsputum specimens, a PCR-based diagnostic test has been advocated as auseful screening procedure to alleviate the need for bronchoscopy.

Treatment

Trimethoprim-sulfamethoxazole (T-S) is the agent of choice for thetreatment of PCP and should be started intravenously (13). Unfortunately,there is a significant array of side-effects associated with this in HIVpositive patients including rash (up to 20%), fever, elevated liver functiontests, neutropenia and thrombocytopenia. More worryingly, the StevensJohnson syndrome, which represents one of the more severe manifestationsof rash, may also occur and this is associated with considerable morbidityand even mortality. Assaying blood levels of T-S may help to optimizedosage and minimize side-effects, but this service is not available in all

184 Chapter 10

centers. Mutations in the P. carinii DHPS gene have been described andthese reflect changes in the amino acid sequences at the sulpha-binding site(14). These mutations have been associated with a three-fold higher risk ofdeath and, therefore, monitoring for T-S drug resistance may shortly becomeroutine.Pentamidine, which has a slower onset of action compared with T-S, and

dapsone, which is also associated with significant side effects (such asneutropenia), and atovaquone, are among the alternative medications. Whilepentamidine is considered 70% effective (13), there is less experience withthe other agents compared with T-S. Newer agents, such as the macrolides,e.g. azithromycin, and the echinocandins may have a role, particularly incombination with T-So Corticosteroids are of benefit in hypoxic patientsduring the first seven days, but should be reduced over time. Otheradjunctive therapies such as monocyte-macrophage stimulating factors andsurfactant remain experimental.

Prevention

Recommendations for primary and secondary prophylaxis of PCP areundergoing radical change due to the success of HAART. T-S is therecommended prophylactic agent for patients with a CD4 count of <200 permm3 and an adverse reaction, unless very severe, should not result indiscontinuation (15,16). It is now believed that PCP prophylaxis can bediscontinued in patients responding to HAART when the CD4 count exceeds200 and this count is also likely to be associated with a low viral load (16).Patients who have had a history of PCP should be administered secondaryprophylaxis, similar to the regimen above, to prevent recurrence. Again thismay be discontinued when the CD4 count rises to above 200. Common sensesuggests that susceptible patients, e.g. HN-positive patients with low CD4counts and a high viral load, should not share a hospital room with a patientinfected with P. carinii (16). However, patients with PCP do not requireroutine source isolation.

ASPERGILLOSIS

Mycology

The first description of aspergillosis occurred nearly two hundred years ago,but its importance only became fully recognised with the advent of anticancer chemotherapy and the increasing population of immunosuppressedpatients at risk. There are approximately 150 species of Aspergillus, but A.


fumigatus, A. flavus, A. niger and A. terreus are the most common speciesisolated from clinical specimens (17). These fungi grow on most culturemedia and identification is usually made on the basis of colonial andmicroscopic appearances.Suggested pathogenic factors include acceleration of growth by

physiologic and pharmacologic concentrations of hydrocortisone, thebinding of laminin and fibrinogen, and impaired macrophage function (17).

Epidemiology

The incidence of invasive aspergillosis has risen over the past two decadesdue to aggressive cancer chemotherapy, the expansion of organ transplantprograms and the advent of the AIDS pandemic. It is the second mostcommon invasive fungal infection in cancer patients, accounting forapproximately 30% of infections; many of these occur in patients withneutropenia (18).Risk factors for Aspergillus infection include: prolonged severe

neutropenia; recent administration of broad-spectrum antibiotics; long-termuse of corticosteroids; transplantation; cytotoxic agents; immunosuppressivetherapy, such as anti-lymphocyte globulin; prolonged use of indwellingcatheters and parenteral nutrition.Aspergillus spores are ubiquitous and the primary ecological niche is

believed to be decomposing plant material. Many infections are communityacquired and therefore difficult to prevent. Most infections are sporadic, butclusters of cases occur in association with hospital building work, where airspore counts are high (17,19). Occasional outbreaks or clusters of cases havebeen described in ICUs, but most of these patients have had somepredisposition, such as chronic chest disease or underlying illnessesrequiring corticosteroids (20,21). In one report, three of six infected patientswere on corticosteroids and fibrous insulation material above a false ceilingwas believed to be the source (21). Aspergillus species may also berecovered from food items, such as pepper, water and fomites (18).

Clinical course

Aspergillus infection may be confined to the respiratory tract, where itcauses a necrotizing bronchopneumonia, or it may result in disseminatedinfection. Patients may initially have no respiratory symptoms, buthemoptysis and a pleural rub are characteristic of Aspergillus pneumonia.Cough, fever and dyspnea are features of tracheobronchitis, which is morecommon in persons with AIDS, compared with other at-risk patients.

186

Diagnosis

Chapter 10

A diagnosis of pulmonary or invasive aspergillosis is confirmed followingclinical suspicion, diagnostic imaging and microbiological investigations.Histopathologic evidence ofAspergillus invasion of tissues remains the 'goldstandard for diagnosis as this is unequivocal confirmation of infection, butobtaining suitable tissue for analysis is not always feasible.

In patients with risk factors, especially in those with a fever unresponsiveto antibacterial agents, aspergillosis should be suspected until provenotherwise. It should also be remembered that aspergillosis occasionallyoccurs outside the high-risk group of patients with prolonged and severeneutropenia. Patients with chronic obstructive pulmonary disease, especiallythose on systemic or inhaled corticosteroids and liver transplant recipientsare also at risk (22,23). Although bacterial infection was the commonestcause of pneumonia in a series of 90 consecutive liver transplant patients,invasive aspergillosis occurred in almost 50% of individuals presenting withpneumonia between 0 and 30 days post-transplantation (23).A plain chest radiograph may show abnormalities suggestive of

pulmonary aspergillosis, but these are usually non-specific and should befollowed up with computerized tomographic (CT) or magnetic resonanceimaging. An area of consolidation with a low attenuation signal, described asa halo sign, is a characteristic feature on CT scans (17). A needle biopsy orsurgical resection, depending upon the location of the lesion and thecondition of the patient, may confirm this.Culture of sputum in the at-risk patient is disappointing and may be

negative in the presence of advanced disease. It may also be positive inpatients without clinical or radiological evidence of aspergillosis,representing colonization or even specimen contamination (24). In a study of80 at-risk patients, the number of positive cultures was significantly greaterin patients with histologically-confirmed aspergillosis than in patients withno evidence of infection (25). However, when culture results frombronchoscopic specimens were considered, the number of positive culturesin patients with confirmed aspergillosis was similar to that in patients whowere not infected. Consequently, a positive culture result is suggestive in anat-risk patient with clinical evidence of infection, but many infected patientswill remain culture negative. The isolation of an Aspergillus species from apatient at risk should be considered significant until proven otherwise. Theyield from blood cultures is disappointing, but increasing the volume ofblood sampled, the frequency of sampling, and using specific fungal mediamay improve yield (24).A number of other approaches have been adopted to enhance the

diagnosis of Aspergillus infection, such as detecting the presence of


galactomannan or testing for Aspergillus antibodies. Screening for thepresence of fungal products, such as galactomannan, two to three times perweek, is quite successful in diagnosis (26,27). However, such tests are notroutine or widely available. False positive results with antigen tests can,however, occur due to the presence of galctomannan in many food items,such as pasta (27). The sensitivity and specificity of antibody tests is low,but antibody titers may rise as the patient improves and the degree ofimmunosuppression wanes. Nonetheless, antigen and antibody tests, whereavailable are useful when used in combination with radiologic and otherdiagnostic approaches.PCR-based procedures offer some hope for a reliable and rapid diagnosis

of Aspergillus infection, particularly if incorporated into a multiplex PCRapproach that also allows detection of other fungi. There is still much workto be done in detennining the most useful primers, establishing thesensitivity of PCR for a range of specimens, avoiding cross-reactions anddeciding how best to combine PCR with conventional approaches. From atotal of 315 blood and bronchoalveolar lavage samples in one recent study,there was 100% correlation between positive histology, culture, or highresolution CT imaging, and PCR (28). The test was 89% specific using atwo-step PCR assay that amplified a region of the 18S rRNA gene.

Treatment

Intravenous amphotericin B remains the drug of choice for the empmctreatment of suspected Aspergillus infection (29). The suggested dose is 1.01.5 mglkg per day. Side-effects include altered renal function, chills andfever, and electrolyte disturbances which are usually reversible, but may bepotentiated by cyclosporin and aminoglycosides. In patients with aconfinned diagnosis of aspergillosis, and where amphotericin B is not welltolerated, lipid-associated fonnulations such as liposomal amphotericin B(LAB, AmBisome) are recommended (30). Despite the fact that there are norandomized controlled trials comparing conventional with lipid-associatedamphotericin B, these new fonnulations are increasingly being used. In astudy comparing conventional amphotericin B with LAB as empiricantifungal therapy in 343 patients, there were fewer breakthrough fungalinfections amongst those treated with LAB and there was a lower incidenceof side-effects. However, the outcome in tenns of resolution of infection andmortality were similar (31). A recent European Organisation for Researchand Treatment of Cancer trial has suggested that a lower dose of LAB of 1mglkg is as effective as a 4 mglkg dose in the treatment of invasiveaspergillosis (32). This has significant cost implications for most centers asLAB is considerably more expensive than conventional preparations.

188 Chapter 10

Alternatives to amphotericin B include itraconazole, but not fluconazole,which has no activity against moulds (29).

Prevention

Strategies aimed at reducing aspergillosis include minimizing environmentalexposure through air filtration, sealing off areas of the hospital undergoingconstruction or refurbishment, and simple hygiene measures such as dailydamp-dusting of horizontal surfaces to reduce dust and Aspergillus sporebuild-up (19). Ideally, patients with a neutrophil count of < 0.5 x 109/Lshould be nursed in protective isolation. Where possible the duration ofneutropenia and the use of broad-spectrum antibiotics should be kept to aminimum when clinically feasible. If air sampling is performed to detectAspergillus, the objective should be clearly stated in advance, as both thesampling and the interpretation of the results require careful consideration(33).Recent reviews and meta-analyses have failed to show convincing benefit

for the routine use of antifungal agents for prophylaxis although bothitraconazole and aerosolized amphotericin B have been advocated. However,patients with a previous history of invasive aspergillosis who are likely toundergo a subsequent episode of neutropenia, should receive prophylacticintravenous amphotericin B. The use of cytokines such as granulocytecolony-stimulating factor may reduce the duration of neutropenia and hencelower the risk (19).

REFERENCES

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2. Miller R. mv-associated respiratory diseases. Lancet 1996;348:307-12.3. Torres A, E1-Ebiary M, Marrades R, el al. Aetiology and prognostic factors of patients

with AIDS presenting life-threatening acute respiratory failure. Eur Resp J 1995;8: 19228.

4. Gill JK, Greene L, Miller R, et ai. ICU admission in patients infected with the humanimmunodeficiency virus: a multicentre survey. Anaesthesia 1999;54:727-32.

5. Rosen MJ, Clayton K, Schneider RF, el ai. Intensive care of patients with HIV infectionUtilization, critical illnesses and outcomes. Am J Respir Crit Care Med 1997;155:67-71.

6. Bedos JP, Dumoulin JL, Gachot B, et ai. Pneumocyslis carinii pneumonia requiringintensive care management: survival and prognostic study in 110 patients with humanimmunodeficiency virus. Crit Care Med 1999;27: 1109-15.

7. Curtis JR, Bennett CL, Homer RD, et ai. Variations in intensive care unit utilization forpatients with human immunodeficiency virus-related Pneumocystis carinii pneumonia:importance of hospital characteristics and geographic location. Crit Care Med1998;26:668-75.


8. Curtis JR. ICU outcomes for patients with HIV infection, a moving target. Chest1998;113:269-70.

9. Kumar SD, Krieger BP. CD4 lymphocyte counts and mortality in AIDS patientsrequiring mechanical ventilator support due to Pneumocystis carinii pneumonia. Chest1998;113:430-3.

10. Forrest DM, Djurdjev 0, Zala C, et al. Validation of the modified multisystem organfailure score as a predictor of mortality in patients with AIDS-related Pneumocystiscarinii pneumonia and respiratory failure. Chest 1998;114: 199-206.

I I. Shelhamer JH, Gill VJ, Quinn TC, et al. The laboratory evaluation of opportunisticpulmonary infections. Ann Intern Med 1996;124:585-99.

12. Caliendo AM, Hewitt PL, Allega JM, et al. Perfonnance of a PCR assay for detection ofPneumocystis carinii from respiratory specimens. J Clin Microbiol 1998;36:979-82.

13. Fishman JA. Treatment of infection due to Pneumocystis carinii Antimicrob AgentsChemother 1998;42: 1309-14.

14. Meshnick SR. Drug-resistant Pneumocystis carinii. Lancet 1999;354: 1318-9.15. U.S. Public Health Service and Infections Diseases Society of America Prevention ofOpportunistic Infections Working Group. 1999 USPHS/IDSA guidelines for theprevention of opportunistic infections in persons infected with human immunodeficiencyvirus. Ann Intern Med 1999;131 :873-903.

16. Kovacs JA, Masur H. Prophylaxis against opportunist infections in patients with humanimmunodeficiency virus infection. N Engl J Med 2000;342: 1416-29.

17. Denning DW. Invasive aspergillosis. Clin Infect Dis 1998;26:781-805.18. Manuel RJ, Kibbler Cc. The epidemiology and prevention of invasive aspergillosis. JHosp Infect 1998;39:95-109.

19. Fridkin SK, Jarvis WR. Epidemiology of nosocomial fungal infections. Clin MicrobiolRev 1996;9:499-511.

20. Hovenden JL, Nicklason F, Barnes RA. Invasive pulmonary aspergillosis in nonimmunocompromised patients. BMJ 1991 ;302:583-4.

21. Humphreys H, Johnson EM, Warnock DW, et al. An outbreak of aspergillosis in ageneral ITU. J Hosp Infect 1990;18:167-77.

22. Pittet D, Huguenin T, Dharan S, et al. Unusual cause of lethal pulmonary aspergillosis inpatients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med1996;154:541-4.

23. Singh N, Gayowski T, Wagener MM, Marino IR. Pulmonary infiltrates in livertransplant recipients in the intensive care unit. Transplantation 1999;67: 1138-44.

24. Denning DW, Evans EGV, Kibbler CC, et al. Guidelines for the investigation of invasivefungal infections in haematological malignancy and solid organ transplantation. Eur JClin Microbiol Infect Dis 1997;16:424-36.

25. Horvath JA, Dummer S. The use of respiratory tract cultures in the diagnosis ofpulmonary aspergillosis. Am J Med 1996; I00: 171-8.

26. Denning DW. Early diagnosis of invasive aspergillosis. Lancet 2000;355:423-4.27. Maertens J, Verhaegen J, Demuynck H, et al. Autopsy-controlled prospective evaluationof serial screening for circulating galactomannan by a sandwich enzyme-linkedimmunosorbent assay for hematological patients at risk for invasive aspergillosis. J ClinMicrobioI1999;37:3223-8.

28. Skladny H, Buchheidt D, Baust C, et al. Specific detection of Aspergillus species inblood and bronchoalveolar lavage samples of immunocompromised patients by two-stepPCR. J Clin Microbiol 1999; 37: 3865-3871.

190 Chapter 10

29. Working Party of the British Society for Antimicrobial Chemotherapy. Therapy of deepfungal infection in haematological malignancy. J Antimicrob Chemother 1997;40:77988.

30. Wong-Beringer A, Jacobs RA, Guglielmo BJ. Lipid formulations of amphotericin B:clinical efficacy and toxicities. Clin Infect Dis 1998;27:603-18.

31. Walsh TJ, Finberg RW, Arndt C, et al. Liposomal amphotericin B for empirical therapyin patients with persistent fever and neutropenia. N Engl J Med 1999;340:764-71.

32. Ellis M, Spence 0, de Pauw B, et al. An EORTC international multicenter randomizedtrial (EORTC number 19923) comparing two dosages of liposomal amphotericin B fortreatment of invasive aspergillosis. Clin Infect Dis 1998;27:1406-12.

33. Morris G, Kokki MH, Anderson K, Richardson MD. Sampling of aspergillus spores inair. J Hosp Infect 2000;44:81-92.

Index

Absidia species, infection by. SeeZygomycosis

Acute disseminated candidiasis, 106Amphotericin Bin aspergillosis, 187in Candida arthritis, 158in Candida peritonitis, 134in candidemia, 36, 130-132in candidiasis, 36,130-134, 145in candiduria, 29,133,155characteristics, 142in cryptococcosis, 175empiric use,in neutropenic patients, 135

in endemic mycoses, 174and fluconazole,for Candida endocarditis, 154for candidemia, 132

and flucytosine,for Candida endocarditis, 154for Candida meningitis, 156for cryptococcosis, 175for trichosporonosis, 173

in Fusarium infection, 167prevention of aspergillosis, 188prophylactic use,in neutropenic patients, 135, 147

resistance, in Scedosporium species,169

toxicity, 36, 142, 145

in zygomycosis, 172Amphotericin B, lipid forms ofin aspergillosis, 187in Candida endocarditis, 154in Candida endophthalmitis, 157in candidiasis, 36characteristics, 36, 142-143, 145empiric use,in neutropenic patients, 135

in endemic mycoses, 174in Fusarium infection, 167in hepatosp1enic candidiasis, 155toxicity, 143, 145in zygomycosis, 172

Anesthetic agentsand candidiasis, 33-34

Antibioticsand candidiasis, 28misuse in intensive care units, 29-30and overgrowth ofCandida species, 6,28,48

prevention of resistance, 30use in intensive care units, 149

Antibody detectionin aspergillosis, 76, 187in candidiasis, 64-65in zygomycosis, 87

Antigen detectionin aspergillosis, 76-79, 187in candidiasis, 65-69

192

Apophysomyces species, infection by. SeeZygomycosis

Arabinitol, detectionin candidiasis, 69-72

Arthritis, due toCandida species, 158

Aspergillosisantibody detection in, 76, 187antigen detection in, 76-79, 187blood culture in, 74, 186bronchoalveolar lavage in, 74, 77, 82,120

causal fungi, 72, 184-185clinical manifestations, 120, 185computed tomography in, 84, 120, 186diagnosis, 72-84, 120, 186-187immunohistological diagnosis, 75incidence, 119, 185of lung, 120, 185-186nasal culture in, 74prevention, 188risk factors, 185sputum culture in, 74, 120, 186tissue appearance, 72, 73, 74treatment, 187-188

Aspergillosis, neonatalclinical manifestations, 120

Aspergillus jlavusinfection by. See Aspergillosis

Aspergillus fumigatusinfection by. See Aspergillosis

Aspergillus speciesgalactomannan as diagnostic marker,76-79

glucan as diagnostic marker, 82-86immunodominant antigens, 76, 78infection by. See Aspergillosisisolation from environment, 185isolation from respiratory tract, 120,186

molecular probes for, 75, 79-82nosocomial outbreaks, 185proteins as diagnostic markers, 78

Aspergillus terreusinfection by. See Aspergillosis

Azole antifungals, see named drugs

Biotherapeutic agentsand gut colonization, 148

Index

Blastomycosis, 174Blood culture, for diagnosis ofaspergillosis, 74, 186candidiasis, 59-63,107, lIS, 130,151-154

Fusarium infection, 86, 167Malassezia infection, 86trichosporonosis, 86

Braincandidiasis of, 157zygomycosis of, 170

Bronchoalveolar lavage, in diagnosis ofaspergillosis, 74, 77, 82

Burnsand candidiasis, 6and fungal infection, 26

Candida albicanscross-infection, 15,31,34,35,146enolase as diagnostic marker, 68hands as source of infection, 15immunodominant antigens, 65, 66, 68incidence in bloodstream infection, 3,4,6,27,30,31,141

incidence in urinary tract infection,30,31

infection by. See also Candidiasismannan as diagnostic marker, 66-67molecular sub-typing, 15, 18neonatal candidemia, 5nosocomial outbreaks, 15prior colonization as predictor ofinfection, 47, 109

proteinase as diagnostic marker, 65-66Candida dubliniensisdifferentiation from Candida albicans,58,64

Candida glabratacross-infection, 17,31fluconazole resistance, 50, 131, 141incidence in bloodstream infection, 3,4,6,27,31,141

incidence in urinary tract infection, 28infection by. See also Candidiasisitraconazole resistance, 141molecular sub-typing, 17and older age, 14

Candida guilliermondiipseudo-outbreak, 17

Index

Candida kruseicross-infection, 31fluconazole resistance, 13 I, 141incidence in bloodstream infection, 4,141

infection by. See also Candidiasisitraconazole resistance, 141

Candida lusitaniaecross-infection, 17hands as source of infection, 17infection by. See also Candidiasismolecular sub-typing, 17nosocomial outbreaks, 17

Candida parapsilosiscross-infection, 16,35, 146hands as source of infection, 16incidence in bloodstream infection, 4,6,27,30, 141

incidence in urinary tract infection, 31infection by. See also Candidiasismolecular sub-typing, 16neonatal candidemia, 5, 31nosocomial outbreaks, 5, 16,26and parenteral nutrition, 7, 14, 16and pressure transducers, 31pseudo-outbreaks, 16and vascular catheters, 7, 14, 16

Candida rugosacross-infection, 17hands as source of infection, 17nystatin resistance, 147

Candida specieschanging distribution, 4, 14, 31, 105,131,141,147

colonization rates in neonates, 115contaminated fluids as source ofinfection, 34

cross-infection, 13-19,24-25,31glucan as diagnostic marker, 82-86hands as source of infection, 24, 25,26,34,45

identification of, 57-59incidence in bloodstream infection,141

infection by. See also Candidiasisisolation from respiratory tract, 27,48,111,118,132

molecular probes for, 64, 79-82molecular sub-typing, 6, 18

193

natural habitat of, 6, 14,45nosocomial infection rates, 2-3, 23, 27prior colonization as predictor ofinfection, 7, 47, 108-109, 115-116

role in nosocomial pneumonia, 27, 48transmission of, 24-25

Candida tropicaliscross-infection, 17,31,35,146hands as source of infection, 17incidence in bloodstream infection, 4,6,30,141

incidence in urinary tract infection, 3 Iinfection by. See also Candidiasismolecular sub-typing, 17, 18nosocomial outbreaks, 17and oncologic patients, 14prior colonization as predictor ofinfection, 47, 109

Candidemiacausal fungi, 3, 4, 5, 6, 27, 30clinical manifestations, 106hands as source of infection, 15, 16,17,26

hospitalization costs, 8incidence, 2-3, 5, 23, 27-28, 105incidence in bums patients, 6medical devices, 16mortality rates, 7, 23population-based surveillance, 3predictors of poor outcome, 8prevention, 8risk factors, 6-7, 27,106-107treatment, 130-132, 146, 150-154

Candidemia, neonatalcausal fungi, 4, 5, 30-31, 34,116clinical manifestations, 34, 107complications, 34hands as source of infection, 15, 16,17

incidence, 5, 27-28, 34, 116and medical devices, 16and parenteral nutrition, 15,24population-based surveillance, 3and pressure transducers, 31-32risk factors, 7, 27, 34, 116suppositories as source of infection,26

Candidiasisand anesthetic agents, 33-34

194

and antibiotics, 6, 28antibody detection in, 64-65antigen detection in, 65-69arabinitol detection in, 69-72arthritis, 158biliary tract, 110blood culture in, 59-63, 107, 115, 130,151-154

of brain, 157and burns, 6and catheters, vascular, 7,107,131,151,154

of central nervous system, 156-157chorioretinitis, 112-113, 157and circulatory assist devices, 32clinical manifestations, 108-115computed tomography in, 110, 111,156

diagnosis, 56-72endocarditis, 32, 115, 154-155endophthalmitis, 33, 112-113, 115,157

of eye, 112-113, 157immune response, 49immunohistological diagnosis of, 64incidence, 2-3, 23of liver, 110-111, 155of lung, 27, 111, 132mediastinitis, 114meningitis, 33, 112, 156and neurosurgical devices, 33and organ failure, 50osteomyelitis, 33, 157-158pancreatitis, 50, 110and peritoneal dialysis, 110peritonitis, 49-50, 109, 133-134, 156and pressure transducers, 31prevention, 37,146-149risk factors, 23-34,46-51, 112, 129,146

of spleen, Ill, 155tissue appearance, 57, 63treatment, 29, 35-37,130-136,145,150-158

of urinary tract, 28, 47, 113-114, 133,155

Candidiasis, neonatalclinical manifestations, 107, 116-119of lung, 118

Index

meningitis, 117oropharynx, 117and peritoneal dialysis, 119peritonitis, 118-119risk factors, 47,50, 115-116and spontaneous intestinal perforation,118-119

of urinary tract, 29, 50, 117Candiduriacausal fungi, 28-29, 30in neonates, 29, 50, 117-118risk factors for renal infection, 28,113-114

significance, 28, 47-48, 63, 109, 113114,117-118,133,155

treatment, 29, 48,133,155Cand-Tec Candida detection test, 68-69,84

Catheters, vascularand Candida parapsilosis infection, 7,14,16

and candidiasis, 7,107,131,151,154prevention of infection, 38

Central nervous systemcandidiasis of, 156-157

Central venous catheters. See Catheters,vascular

Cerebrospinal fluid, findings incandidiasis, 112, 117, 156cryptococcosis, 174

Chorioretinitis, due toCandida species, 112-113, 157

Chronic disseminated candidiasis, 106,110-111

Chronic necrotizing aspergillosis, 120Circulatory assist devicesand candidiasis, 32

Coccidioidomycosis, 174Computed tomography, in diagnosis ofaspergillosis, 84, 120, 186hepatosplenic candidiasis, 111, 156pancreatic candidiasis, 110pulmonary candidiasis, 111

Continuous ambulatory peritonealdialysis. See Peritoneal dialysis

C-reactive protein, as diagnostic markerin candidiasis, 107-108, 152

Cryptococcosisclinical manifestations, 174

Index

diagnosis, 174oflung,174meningitis, 174treatment, 175

Cryptococcus neoformansantigenic cross-reaction with

Trichosporon asahii, 86, 173infection by. See Cryptococcosis

Cunninghamella species, infection by.See Zygomycosis

Cytokinesuse in fungal infection, 49, 168, 188

Directigen Disseminated CandidiasisTest, 68

Endemic mycoses, 173-174. See alsonamed infections

Endocarditis, due toCandida species, 32,115,154-155

Endophthalmitis, due toCandida species, 33,112-113,115,157

Endotracheal intubationand fungal infection, 25

Environmental factors, and fungalinfection, 26. See also named factors

Enzyme immunoassay, for antibodydetectionin candidiasis, 65, 67in zygomycosis, 87

Enzyme immunoassay, for antigendetectionin aspergillosis, 76in candidiasis, 66, 67

Eyecandidiasis of, 112-113, 157

Fluconazoleand amphotericin B,for Candida endocarditis, 155for candidemia, 131

in Candida endocarditis, 154in Candida endophthalmitis, 157in Candida peritonitis, 49, 134, 145in candidemia, 36, 130-132in candidiasis, 36, 130-134, 145in candiduria, 29,133,155characteristics, 144

195

in cryptococcosis, 175and distribution of Candida species, 4,31,50,131,147

in endemic mycoses, 174prophylactic use,in liver transplant recipients, 147in neutropenic patients, 4,8, 134,147in surgical patients, 8, 49,135,148

resistance, 30,131,141,145,148side-effects, 144, 145in trichosporonosis, 173

Fungal infectionsand bums, 26and cytokines, 49, 168, 188and endotracheal intubation, 25hospital discharge rates, 23hospitalization rates, Iand immunoparesis, 48-49and malnutrition, 26mortality rates, Iand mucosal damage, 25, 48and parenteral nutrition, 26, 48risk factors, 25,139-140and skin damage, 25, 48

Fusarium species, infection byblood culture in, 86, 167causal fungi, 86, 165clinical manifestations, 166-167diagnosis, 86, 167prevention, 168risk factors, 166tissue appearance, 74, 166treatment, 167-168

GaJactomannan, as diagnostic markerin aspergillosis, 75, 76

Glovesand prevention of infection, 37

Glucan, detectionin aspergillosis, 82-86in candidiasis, 82-86

Hand washingand prevention of candidiasis, 8, 19and prevention of infection, 37

Health care workerscompliance in hand washing, 17,37

196

hands as source of infection, 15, 16,17,24-25,26,27,34,37,45

incidence of Candida colonization, 19,25

Histoplasmosis, 174Host defects, and fungal infection, 25-26.

See also named defects

Immunodiffusionin aspergillosis, 76in candidiasis, 65in zygomycosis, 87

Immunodominant antigensAspergillus species, 76, 78Candida albicans, 65, 66, 68

Immunohistology, for diagnosis ofaspergillosis, 74candidiasis, 64

Immunoparesisand fungal infection, 48-49

In-situ hybridizationofAspergillus species, 75ofCandida species, 64

Itraconazole, 135, 144in aspergillosis, 188in endemic mycoses, 174prevention of aspergillosis, 188prophylactic use,in neutropenic patients, 135, 147

resistance, 141in Scedosporium infection, 169in trichosporonosis, 173in zygomycosis, 172

Ketoconazoleprophylactic use,in neutropenic patients, 147

Latex agglutination, for antigen detectionin aspergillosis, 76in candidiasis, 67

Light Cycler system for diagnosis ofaspergillosis, 81candidiasis, 81

Livercandidiasis of, 110-111, 155

Liver transplantationand aspergillosis, 186and candidiasis, 110

Index

Lungaspergillosis of, 120, 185blastomycosis of, 174candidiasis of, 27, Ill, 118, 132coccidioidomycosis of, 174cryptococcosis of, 174histoplasmosis of, 174pneumocystosis of, 182-184zygomycosis of, 170

Malassezia species, infection byblood culture in, 86clinical manifestations, 119diagnosis, 86

Malnutritionand fungal infection, 26

Mannan, as diagnostic markerin candidiasis, 66-67

Mediastinitis, due toCandida species, 114

Meningitis, due toCandida species, 33, 112, 117, 156Cryptococcus neoformans, 174

Microbiological surveillancerole in intensive care units, 108-109,149-150

Molecular probes, for diagnosis ofaspergillosis, 75, 79candidiasis, 64, 79

Molecular sub-typingCandida albicans, 15, 18Candida glabrata, 17Candida lusitaniae, 17Candida parapsilosis, 16Candida species, 6, 18Candida tropicalis, 17, 18

Monoclonal antibodies in antigendetectionaspergillosis, 75, 77candidiasis, 64, 68pneumocystosis, I83

Mucor species, infection by. SeeZygomycosis

Mucormycosis. See ZygomycosisMucosal damageand fungal infection, 25, 48

Neurosurgical devicesand candidiasis, 33

Index

Nystatinprophylactic use,in bums patients, 148in intensive care patients, 149in neutropenic patients, 147

Organ failure, as risk factor forcandidiasis, 50

Oropharynxcandidiasis of, 117

Osteomyelitis, due toCandida species, 33,157-158

Pancreatitis, due toCandida species, 50, 110

Paracoccidioidomycosis, 174Parenteral nutritionand Candida parapsilosis infection, 7,14,16

and fungal infection, 26, 48and neonatal candidemia, 24

Pastorex Aspergillus detection test, 77, 84Penicillium marnefJei, infection by, 174Pentamidinein pneumocystosis, 184

Peritoneal dialysisand candidiasis, 109-110, 119

Peritonitis, due toCandida species, 49-50,109,118-119,133-134,145,156

Platelia Aspergillus detection test, 77-78Pneumocystis cariniiclassification as fungus, 181-182infection by. See Pneumocystosis

Pneumocystosisand AIDS, 182clinical manifestations, 182-183diagnosis, 183of lung, 182-183prevention, 184treatment, 183-184

Polymerase chain reaction-basedmethods, for diagnosis ofaspergillosis, 79-82, 187candidiasis, 79-82pneumocystosis, 183

Posaconazole,in Fusarium infection, 168in Scedosporium infection, 169

197

in zygomycosis, 172Pressure transducersand Candida parapsilosis infection,31-32

and candidiasis, 31-32and neonatal candidemia, 31

Proteinase, as diagnostic markerin candidiasis, 65-66

Pseudallescheria boydiiinfection by. See Scedosporiumspecies

Rhizomucor species, infection by. SeeZygomycosis

Rhizopus species, infection by. SeeZygomycosis

Rhodotorula species, infection byclinical manifestations, 119

Saksenaea species, infection by. SeeZygomycosis

Scedosporium apiospermumamphotericin B resistance, 168-169infection by. See Scedosporiumspecies

Scedosporium prolificansantifungal drug resistance, 169infection by, 169

Scedosporium species, infection byclinical manifestations, 168-169risk factors, 168tissue appearance, 74, 169treatment, 169

Serological tests. See named infectionsand procedures

Sinuszygomycosis of, 170

Skin damageand fungal infection, 25, 48

Spleencandidiasis of, 111, 155

TaqMan system for diagnosis ofaspergillosis, 81candidiasis, 81

Trichosporon asahiiantigenic cross-reaction with

Cryptococcus neoformans, 86, 173infection by. See Trichosporonosis

198

Trichosporonosisclinical manifestations, 173diagnosis, 86, 173risk factors, 173tissue appearance, 173treatment, 173

Trimethoprim-sulfamethoxazolein pneumocystosis, 183-184side-effects, 183

Urinary tractcandidiasis of, 28-29, 47, 50, 113-114,117,133,155

Voriconazolein Fusarium infection, 168in Scedosporium infection, 169

Zygomycosisantibody detection in, 87blood culture in, 171causal fungi, 87, 169clinical manifestations, 170diagnosis, 87, 171risk factors, 170sputum culture in, 171tissue appearance, 87, 170, 171treatment, 171-172

Index

fungal infection in the intensive care unit

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