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WHO/CDS/CSR/EPH/2002.12

Prevention of hospital-acquired infectionsA practical guide2nd edition

World Health OrganizationDepartment of Communicable Disease,Surveillance and Response

This document has been downloaded from the WHO/CSR Web site. The original coverpages and lists of participants are not included. See http://www.who.int/emc for moreinformation.

© World Health OrganizationThis document is not a formal publication of the World Health Organization (WHO), andall rights are reserved by the Organization. The document may, however, be freelyreviewed, abstracted, reproduced and translated, in part or in whole, but not for sale norfor use in conjunction with commercial purposes.

The views expressed in documents by named authors are solely the responsibility ofthose authors. The mention of specific companies or specific manufacturers' productsdoes no imply that they are endorsed or recommended by the World Health Organizationin preference to others of a similar nature that are not mentioned.

Prevention ofhospital-acquired

infectionsA PRACTICAL GUIDE

2nd edition

Editors

G. Ducel, Fondation Hygie, Geneva, Switzerland

J. Fabry, Université Claude-Bernard, Lyon, France

L. Nicolle, University of Manitoba, Winnipeg, Canada

Contributors

R. Girard, Centre Hospitalier Lyon-Sud, Lyon, France

M. Perraud, Hôpital Edouard Herriot, Lyon, France

A. Prüss, World Health Organization, Geneva, Switzerland

A. Savey, Centre Hospitalier Lyon-Sud, Lyon, France

E. Tikhomirov, World Health Organization, Geneva, Switzerland

M. Thuriaux, World Health Organization, Geneva, Switzerland

P. Vanhems, Université Claude Bernard, Lyon, France

WHO/CDS/CSR/EPH/2002.12DISTR: GENERAL

ORIGINAL: ENGLISH

WORLD HEALTH ORGANIZATION

Acknowledgements

The World Health Organization (WHO) wishes to acknowledge the significant support for this work from theUnited States Agency for International Development (USAID).

This document was developed following informal meetings of the editorial working group in Lyon and Ge-neva from 1997 to 2001.

The editors wish to acknowledge colleagues whose suggestions and remarks have been greatly appreciated:Professor Franz Daschner (Institute of Environmental Medicine and Hospital Epidemiology, Freiburg, Ger-many), Dr Scott Fridkin (Centers for Disease Control and Prevention, Atlanta, USA), Dr Bernardus Ganter(WHO Regional Office for Europe, Copenhagen, Denmark), Dr Yvan Hutin (Blood Safety and Clinical Technol-ogy, WHO, Geneva, Switzerland), Dr Sudarshan Kumari (WHO Regional Office for South-East Asia, New Delhi,India), Dr Lionel Pineau (Laboratoire Biotech-Germande, Marseille, France).

The editors would like to thank Brenda Desrosiers, Georges-Pierre Ducel and Penny Ward for their help inmanuscript preparation.

© World Health Organization 2002

This document is not a formal publication of the World Health Organization (WHO), and all rights are reserved by theOrganization. The document may, however, be freely reviewed, abstracted, reproduced and translated, in part or in whole,but not for sale or for use in conjunction with commercial purposes.

The views expressed in documents by named authors are solely the responsibility of those authors.

The designations employed and the presentation of the material in this document, including tables and maps, do not implythe expression of any opinion whatsoever on the part of the secretariat of the World Health Organization concerning thelegal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers orboundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.

The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recom-mended by WHO in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, thenames of proprietary products are distinguished by initial capital letters.

Designed by minimum graphicsPrinted in Malta

Contents

iii

Introduction 1

Chapter I. Epidemiology of nosocomial infections 4

1.1 Definitions of nosocomial infections 41.2 Nosocomial infection sites 5

1.2.1 Urinary infections 5

1.2.2 Surgical site infections 5

1.2.3 Nosocomial pneumonia 5

1.2.4 Nosocomial bacteraemia 6

1.2.5 Other nosocomial infections 6

1.3 Microorganisms 6

1.3.1 Bacteria 6

1.3.2 Viruses 6

1.3.3 Parasites and fungi 7

1.4 Reservoirs and transmission 7

Chapter II. Infection control programmes 9

2.1 National or regional programmes 9

2.2 Hospital programmes 9

2.2.1 Infection Control Committee 9

2.2.2 Infection control professionals (infection control team) 10

2.2.3 Infection control manual 10

2.3 Infection control responsibility 10

2.3.1 Role of hospital management 10

2.3.2 Role of the physician 10

2.3.3 Role of the microbiologist 11

2.3.4 Role of the hospital pharmacist 11

2.3.5 Role of the nursing staff 12

2.3.6 Role of the central sterilization service 12

2.3.7 Role of the food service 13

2.3.8 Role of the laundry service 13

2.3.9 Role of the housekeeping service 13

2.3.10 Role of maintenance 14

2.3.11 Role of the infection control team (hospital hygiene service) 14

Chapter III. Nosocomial infection surveillance 16

3.1 Objectives 16

3.2 Strategy 16

3.2.1 Implementation at the hospital level 17

3.2.2 Implementation at the network (regional or national) level 17

3.3 Methods 17

3.3.1 Prevalence study 18

3.3.2 Incidence study 18

3.3.3 Calculating rates 19

3.4 Organization for efficient surveillance 19

3.4.1 Data collection and analysis 20

3.4.2 Feedback/dissemination 23

3.4.3 Prevention and evaluation 23

3.5 Evaluation of the surveillance system 23

3.5.1 Evaluation of the surveillance strategy 23

3.5.2 Feedback evaluation 24

3.5.3 Validity/data quality 24

Chapter IV. Dealing with outbreaks 26

4.1 Identifying an outbreak 26

4.2 Investigating an outbreak 26

4.2.1 Planning the investigation 26

4.2.2 Case definition 26

4.2.3 Describing the outbreak 27

4.2.4 Suggesting and testing a hypothesis 27

4.2.5 Control measures and follow-up 28

4.2.6 Communication 28

Chapter V. Prevention of nosocomial infection 30

5.1 Risk stratification 30

5.2 Reducing person-to-person transmission 30

5.2.1 Hand decontamination 30

5.2.2 Personal hygiene 32

5.2.3 Clothing 32

5.2.4 Masks 33

5.2.5 Gloves 33

5.2.6 Safe injection practices 33

5.3 Preventing transmission from the environment 33

5.3.1 Cleaning of the hospital environment 33

5.3.2 Use of hot/superheated water 34

5.3.3 Disinfection of patient equipment 34

5.3.4 Sterilization 34

Chapter VI. Prevention of common endemic nosocomial infections 38

6.1 Urinary tract infections (UTI) 38

6.2 Surgical wound infections (surgical site infections) 39

iv

PREVENTION OF HOSPITAL-ACQUIRED INFECTIONS: A PRACTICAL GUIDE — WHO/CDS/CSR/EPH/2002.12

6.2.1 Operating room environment 40

6.2.2 Operating room staff 40

6.2.3 Pre-intervention preparation of the patient 40

6.2.4 Antimicrobial prophylaxis 41

6.2.5 Surgical wound surveillance 41

6.3 Nosocomial respiratory infections 41

6.3.1 Ventilator-associated pneumonia in the intensive care unit 41

6.3.2 Medical units 41

6.3.3 Surgical units 41

6.3.4 Neurological patients with tracheostomy 41

6.4 Infections associated with intravascular lines 41

6.4.1 Peripheral vascular catheters 42

6.4.2 Central vascular catheters 42

6.4.3 Central vascular totally implanted catheters 42

Chapter VII. Infection control precautions in patient care 44

7.1 Practical aspects 44

7.1.1 Standard (routine) precautions 44

7.1.2 Additional precautions for specific modes of transmission 44

7.2 Antimicrobial-resistant microorganisms 45

Chapter VIII. Environment 47

8.1 Buildings 47

8.1.1 Planning for construction or renovation 47

8.1.2 Architectural segregation 47

8.1.3 Traffic flow 47

8.1.4 Materials 48

8.2 Air 48

8.2.1 Airborne contamination and transmission 48

8.2.2 Ventilation 48

8.2.3 Operating theatres 49

8.2.4 Ultra-clean air 49

8.3 Water 50

8.3.1 Drinking-water 50

8.3.2 Baths 50

8.3.3 Pharmaceutical (medical) water 51

8.3.4 Microbiological monitoring 51

8.4 Food 51

8.4.1 Agents of food poisoning and foodborne infections 52

8.4.2 Factors contributing to food poisoning 52

8.4.3 Prevention of food poisoning 52

8.5 Waste 53

8.5.1 Definition and classification 53

8.5.2 Handling, storage and transportation of health care waste 54

v

CONTENTS

Chapter lX. Antimicrobial use and antimicrobial resistance 56

9.1 Appropriate antimicrobial use 57

9.1.1 Therapy 57

9.1.2 Chemoprophylaxis 57

9.2 Antimicrobial resistance 57

9.2.1 MRSA (methicillin-resistant Staphylococcus aureus) 58

9.2.2 Enterococci 59

9.3 Antibiotic control policy 59

9.3.1 Antimicrobial Use Committee 59

9.3.2 Role of the microbiology laboratory 59

9.3.3 Monitoring antimicrobial use 60

Chapter X. Preventing infections of staff 61

10.1 Exposure to human immunodeficiency virus (HIV) 61

10.2 Exposure to hepatitis B virus 62

10.3 Exposure to hepatitis C virus 62

10.4 Neisseria meningitidis infection 62

10.5 Mycobacterium tuberculosis 62

10.6 Other infections 62

Annex 1. Suggested further reading 63

Annex 2. Internet resources 64

vi


1

Anosocomial infection — also called “hospital-acquired infection” can be defined as:

An infection acquired in hospital by a patient who wasadmitted for a reason other than that infection (1). An in-fection occurring in a patient in a hospital or other healthcare facility in whom the infection was not present or incu-bating at the time of admission. This includes infectionsacquired in the hospital but appearing after discharge, andalso occupational infections among staff of the facility (2).

Patient care is provided in facilities which range fromhighly equipped clinics and technologically ad-vanced university hospitals to front-line units withonly basic facilities. Despite progress in public healthand hospital care, infections continue to develop inhospitalized patients, and may also affect hospitalstaff. Many factors promote infection among hospi-talized patients: decreased immunity among patients;the increasing variety of medical procedures andinvasive techniques creating potential routes ofinfection; and the transmission of drug-resistantbacteria among crowded hospital populations, wherepoor infection control practices may facilitate trans-mission.

Frequency of infection

Nosocomial infections occur worldwide and affectboth developed and resource-poor countries. Infec-tions acquired in health care settings are among themajor causes of death and increased morbidityamong hospitalized patients. They are a significantburden both for the patient and for public health. Aprevalence survey conducted under the auspices ofWHO in 55 hospitals of 14 countries representing4 WHO Regions (Europe, Eastern Mediterranean,South-East Asia and Western Pacific) showed anaverage of 8.7% of hospital patients had nosocomialinfections. At any time, over 1.4 million people world-wide suffer from infectious complications acquiredin hospital (3). The highest frequencies of nosoco-mial infections were reported from hospitals in the

Eastern Mediterranean and South-East Asia Regions(11.8 and 10.0% respectively), with a prevalence of7.7 and 9.0% respectively in the European and West-ern Pacific Regions (4).

The most frequent nosocomial infections are infec-tions of surgical wounds, urinary tract infections andlower respiratory tract infections. The WHO study,and others, have also shown that the highest preva-lence of nosocomial infections occurs in intensivecare units and in acute surgical and orthopaedicwards. Infection rates are higher among patients withincreased susceptibility because of old age, under-lying disease, or chemotherapy.

Impact of nosocomial infections

Hospital-acquired infections add to functional dis-ability and emotional stress of the patient and may,in some cases, lead to disabling conditions that re-duce the quality of life. Nosocomial infections arealso one of the leading causes of death (5). The eco-nomic costs are considerable (6,7). The increasedlength of stay for infected patients is the greatestcontributor to cost (8,9,10). One study (11) showedthat the overall increase in the duration of hospi-talization for patients with surgical wound infectionswas 8.2 days, ranging from 3 days for gynaecologyto 9.9 for general surgery and 19.8 for orthopaedicsurgery. Prolonged stay not only increases direct coststo patients or payers but also indirect costs due tolost work. The increased use of drugs, the need forisolation, and the use of additional laboratory andother diagnostic studies also contribute to costs.Hospital-acquired infections add to the imbalancebetween resource allocation for primary and sec-ondary health care by diverting scarce funds to themanagement of potentially preventable conditions.

The advancing age of patients admitted to healthcare settings, the greater prevalence of chronic dis-eases among admitted patients, and the increaseduse of diagnostic and therapeutic procedures which

Introduction


2

affect the host defences will provide continuingpressure on nosocomial infections in the future.Organisms causing nosocomial infections can betransmitted to the community through dischargedpatients, staff, and visitors. If organisms are multire-sistant, they may cause significant disease in thecommunity.

Factors influencing the development ofnosocomial infections

The microbial agent

The patient is exposed to a variety of microorgan-isms during hospitalization. Contact between thepatient and a microorganism does not by itself nec-essarily result in the development of clinical disease— other factors influence the nature and frequencyof nosocomial infections. The likelihood of expo-sure leading to infection depends partly on the char-acteristics of the microorganisms, including resistanceto antimicrobial agents, intrinsic virulence, andamount (inoculum) of infective material.

Many different bacteria, viruses, fungi and parasitesmay cause nosocomial infections. Infections may becaused by a microorganism acquired from anotherperson in the hospital (cross-infection) or may becaused by the patient’s own flora (endogenous in-fection). Some organisms may be acquired from aninanimate object or substances recently contami-nated from another human source (environmentalinfection).

Before the introduction of basic hygienic practicesand antibiotics into medical practice, most hospitalinfections were due to pathogens of external origin(foodborne and airborne diseases, gas gangrene, teta-nus, etc.) or were caused by microorganisms notpresent in the normal flora of the patients (e.g. diph-theria, tuberculosis). Progress in the antibiotic treat-ment of bacterial infections has considerably reducedmortality from many infectious diseases. Most in-fections acquired in hospital today are caused bymicroorganisms which are common in the generalpopulation, in whom they cause no or milder dis-ease than among hospital patients (Staphylococcusaureus, coagulase-negative staphylococci, enterococci,Enterobacteriaceae).

Patient susceptibility

Important patient factors influencing acquisition ofinfection include age, immune status, underlying

disease, and diagnostic and therapeutic interventions.The extremes of life — infancy and old age — are as-sociated with a decreased resistance to infection.Patients with chronic disease such as malignant tu-mours, leukaemia, diabetes mellitus, renal failure,or the acquired immunodeficiency syndrome (AIDS)have an increased susceptibility to infections withopportunistic pathogens. The latter are infectionswith organism(s) that are normally innocuous, e.g.part of the normal bacterial flora in the human, butmay become pathogenic when the body’s immuno-logical defences are compromised. Immunosuppres-sive drugs or irradiation may lower resistance toinfection. Injuries to skin or mucous membranesbypass natural defence mechanisms. Malnutrition isalso a risk. Many modern diagnostic and therapeu-tic procedures, such as biopsies, endoscopic exami-nations, catheterization, intubation/ventilation andsuction and surgical procedures increase the risk ofinfection. Contaminated objects or substances maybe introduced directly into tissues or normally ster-ile sites such as the urinary tract and the lower res-piratory tract.

Environmental factors

Health care settings are an environment where bothinfected persons and persons at increased risk ofinfection congregate. Patients with infections or car-riers of pathogenic microorganisms admitted tohospital are potential sources of infection for pa-tients and staff. Patients who become infected in thehospital are a further source of infection. Crowdedconditions within the hospital, frequent transfers ofpatients from one unit to another, and concentra-tion of patients highly susceptible to infection in onearea (e.g. newborn infants, burn patients, intensivecare ) all contribute to the development of nosoco-mial infections. Microbial flora may contaminateobjects, devices, and materials which subsequentlycontact susceptible body sites of patients. In addi-tion, new infections associated with bacteria such aswaterborne bacteria (atypical mycobacteria) and/orviruses and parasites continue to be identified.

Bacterial resistance

Many patients receive antimicrobial drugs. Throughselection and exchange of genetic resistance elements,antibiotics promote the emergence of multidrug-resistant strains of bacteria; microorganisms in thenormal human flora sensitive to the given drug are

3

suppressed, while resistant strains persist and maybecome endemic in the hospital. The widespread useof antimicrobials for therapy or prophylaxis (includ-ing topical) is the major determinant of resistance.Antimicrobial agents are, in some cases, becomingless effective because of resistance. As an antimicro-bial agent becomes widely used, bacteria resistantto this drug eventually emerge and may spread inthe health care setting. Many strains of pneumo-cocci, staphylococci, enterococci, and tuberculosis arecurrently resistant to most or all antimicrobials whichwere once effective. Multiresistant Klebsiella and Pseu-domonas aeruginosa are prevalent in many hospitals.This problem is particularly critical in developingcountries where more expensive second-line anti-biotics may not be available or affordable (12).

Nosocomial infections are widespread. They are im-portant contributors to morbidity and mortality. Theywill become even more important as a public healthproblem with increasing economic and human impactbecause of:

● Increasing numbers and crowding of people.

● More frequent impaired immunity (age, illness,treatments).

● New microorganisms.

● Increasing bacterial resistance to antibiotics (13).

Purpose of this manual

This manual has been developed to be a practical,basic, resource which may be used by individualswith an interest in nosocomial infections and theircontrol, as well as those who work in nosocomialinfection control in health care facilities. It is appli-cable to all facilities, but attempts to provide rationaland attainable recommendations for facilities withrelatively limited resources. The information shouldassist administrators, infection control personnel, andpatient care workers in such facilities in the initialdevelopment of a nosocomial infection control pro-gramme, including specific components of such pro-grammes. Additional reading in specific areas isprovided in the list of WHO relevant documents andinfection control texts at the end of the manual (An-nex 1), as well as relevant references in each chapter.

References

1. Ducel G et al. Guide pratique pour la lutte contrel’infection hospitalière. WHO/BAC/79.1.

2. Benenson AS. Control of communicable diseasesmanual, 16th edition. Washington, American Pub-lic Health Association, 1995.

3. Tikhomirov E. WHO Programme for the Controlof Hospital Infections. Chemiotherapia, 1987, 3:148–151.

4. Mayon-White RT et al. An international surveyof the prevalence of hospital-acquired infection.J Hosp Infect, 1988, 11 (Supplement A):43–48.

5. Ponce-de-Leon S. The needs of developing coun-tries and the resources required. J Hosp Infect, 1991,18 (Supplement):376–381.

6. Plowman R et al. The socio-economic burden of hospi-tal-acquired infection. London, Public Health Labo-ratory Service and the London School of Hygieneand Tropical Medicine, 1999.

7. Wenzel RP. The economics of nosocomial infec-tions. J Hosp Infect 1995, 31:79–87.

8. Pittet D, Taraara D, Wenzel RP. Nosocomial blood-stream infections in critically ill patients. Excesslength of stay, extra costs, and attributable mor-tality. JAMA, 1994, 271:1598–1601.

9. Kirkland KB et al. The impact of surgical-site in-fections in the 1990’s: attributable mortality, ex-cess length of hospitalization and extra costs. InfectContr Hosp Epidemiol, 1999, 20:725–730.

10. Wakefield DS et al. Cost of nosocomial infection:relative contributions of laboratory, antibiotic,and per diem cost in serious Staphylococcus aureusinfections. Amer J Infect Control, 1988, 16:185–192.

11. Coella R et al. The cost of infection in surgicalpatients: a case study. J Hosp Infect, 1993, 25:239–250.

12. Resources. In: Proceedings of the 3rd Decennial Inter-national Conference on Nosocomial Infections, PreventingNosocomial Infections. Progress in the 80’s. Plans for the90’s, Atlanta, Georgia, July 31–August 3, 1990:30(abstract 63).

13. Ducel G. Les nouveaux risques infectieux.Futuribles, 1995, 203:5–32.

INTRODUCTION


4

CHAPTER I

Epidemiology ofnosocomial infections

Changes in health care delivery have resulted inshorter hospital stays and increased outpatient care.It has been suggested the term nosocomial infec-tions should encompass infections occurring inpatients receiving treatment in any health care set-ting. Infections acquired by staff or visitors to thehospital or other health care setting may also beconsidered nosocomial infections.

Simplified definitions may be helpful for somefacilities without access to full diagnostic techniques(17). The following table (Table 1) provides defini-tions for common infections that could be used forsurveys in facilities with limited access to sophisti-cated diagnostic techniques.

TABLE 1. Simplified criteria for surveillance ofnosocomial infections

Type of nosocomial Simplified criteriainfection

Surgical site infection Any purulent discharge, abscess, orspreading cellulitis at the surgicalsite during the month after theoperation

Urinary infection Positive urine culture(1 or 2 species) with at least105 bacteria/ml, with or withoutclinical symptoms

Respiratory infection Respiratory symptoms with atleast two of the following signsappearing during hospitalization:— cough— purulent sputum— new infiltrate on chest

radiograph consistent withinfection

Vascular catheter Inflammation, lymphangitis orinfection purulent discharge at the insertion

site of the catheter

Septicaemia Fever or rigours and at least onepositive blood culture

Studies throughout the world document thatnosocomial infections are a major cause of

morbidity and mortality (1–13). A high frequency ofnosocomial infections is evidence of a poor qualityof health service delivery, and leads to avoidablecosts. Many factors contribute to the frequency ofnosocomial infections: hospitalized patients areoften immunocompromised, they undergo invasiveexaminations and treatments, and patient care prac-tices and the hospital environment may facilitate thetransmission of microorganisms among patients. Theselective pressure of intense antibiotic use promotesantibiotic resistance. While progress in the preven-tion of nosocomial infections has been made, changesin medical practice continually present new oppor-tunities for development of infection. This chaptersummarizes the main characteristics of nosocomialinfections, based on our current understanding.

1.1 Definitions of nosocomial infections

Nosocomial infections, also called “hospital-acquiredinfections”, are infections acquired during hospitalcare which are not present or incubating at admis-sion. Infections occurring more than 48 hours afteradmission are usually considered nosocomial. Defi-nitions to identify nosocomial infections have beendeveloped for specific infection sites (e.g. urinary,pulmonary). These are derived from those publishedby the Centers for Diseases Control and Prevention(CDC) in the United States of America (14,15) or dur-ing international conferences (16) and are used forsurveillance of nosocomial infections. They are basedon clinical and biological criteria, and include ap-proximately 50 potential infection sites.

Nosocomial infections may also be considered eitherendemic or epidemic. Endemic infections are mostcommon. Epidemic infections occur during out-breaks, defined as an unusual increase above thebaseline of a specific infection or infecting organ-ism.

5

1.2 Nosocomial infection sites

An example of the distribution of sites of nosoco-mial infections is shown in Figure 1.

FIGURE 1. Sites of the most comon nosocomialinfections: distribution according to theFrench national prevalence survey (1996)*

organ spaces are identified separately. The infectionis usually acquired during the operation itself;either exogenously (e.g. from the air, medical equip-ment, surgeons and other staff), endogenously fromthe flora on the skin or in the operative site or, rarely,from blood used in surgery. The infecting microor-ganisms are variable, depending on the type andlocation of surgery, and antimicrobials received bythe patient. The main risk factor is the extent ofcontamination during the procedure (clean, clean-contaminated, contaminated, dirty), which is to alarge part dependent on the length of the operation,and the patient’s general condition (25). Other fac-tors include the quality of surgical technique, thepresence of foreign bodies including drains, the viru-lence of the microorganisms, concomitant infectionat other sites, the use of preoperative shaving, andthe experience of the surgical team.

1.2.3 Nosocomial pneumonia

Nosocomial pneumonia occurs in several differentpatient groups. The most important are patients onventilators in intensive care units, where the rateof pneumonia is 3% per day. There is a high case-fatality rate associated with ventilator-associatedpneumonia, although the attributable risk is diffi-cult to determine because patient comorbidity is sohigh. Microorganisms colonize the stomach, upperairway and bronchi, and cause infection in the lungs(pneumonia): they are often endogenous (digestivesystem or nose and throat), but may be exogenous,often from contaminated respiratory equipment.

The definition of pneumonia may be based on clini-cal and radiological criteria which are readily avail-able but non-specific: recent and progressiveradiological opacities of the pulmonary parenchyma,purulent sputum, and recent onset of fever. Diagno-sis is more specific when quantitative microbiologi-cal samples are obtained using specialized protectedbronchoscopy methods. Known risk factors forinfection include the type and duration of ventila-tion, the quality of respiratory care, severity of thepatient’s condition (organ failure), and previous useof antibiotics.

Apart from ventilator-associated pneumonia,patients with seizures or decreased level of con-sciousness are at risk for nosocomial infection, evenif not intubated. Viral bronchiolitis (respiratory syn-cytial virus, RSV) is common in children’s units, andinfluenza and secondary bacterial pneumonia mayoccur in institutions for the elderly. With highly

CHAPTER I. EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS

* Adapted fom Enquête nationale de prévalence des infections nosocomiales,1996. BEH, 1997, 36:161–163.

1.2.1 Urinary infections

This is the most common nosocomial infection; 80%of infections are associated with the use of an ind-welling bladder catheter (1,2,3). Urinary infectionsare associated with less morbidity than other noso-comial infections, but can occasionally lead to bacter-aemia and death. Infections are usually defined bymicrobiological criteria: positive quantitative urineculture (≥105 microorganisms/ml, with a maximumof 2 isolated microbial species). The bacteria respon-sible arise from the gut flora, either normal (Escherichiacoli) or acquired in hospital (multiresistant Klebsiella).

1.2.2 Surgical site infections

Surgical site infections are also frequent: the inci-dence varies from 0.5 to 15% depending on the typeof operation and underlying patient status (18,19,20).These are a significant problem which limit the po-tential benefits of surgical interventions. The impacton hospital costs and postoperative length of stay(between 3 and 20 additional days) (21,22,23,24) isconsiderable.

The definition is mainly clinical: purulent dischargearound the wound or the insertion site of the drain,or spreading cellulitis from the wound. Infections ofthe surgical wound (whether above or below theaponeurosis), and deep infections of organs or

Urinary tract U

Lower respiratorytract R1Surgical

site S

Skin andsoft tissue SST

Respiratory tract(other) R2

Bacteraemia B

ENT/Eye E/E

Catheter site C

Othersites O

U

RIS

SST

R2

B

E/E

OC


6

immunocompromised patients, Legionella spp. andAspergillus pneumonia may occur. In countries witha high prevalence of tuberculosis, particularlymultiresistant strains, transmission in health caresettings may be an important problem.

1.2.4 Nosocomial bacteraemia

These infections represent a small proportion ofnosocomial infections (approximately 5%) but case-fatality rates are high — more than 50% for somemicroorganisms. The incidence is increasing, particu-larly for certain organisms such as multiresistantcoagulase-negative Staphylococcus and Candida spp.Infection may occur at the skin entry site of theintravascular device, or in the subcutaneous path ofthe catheter (tunnel infection). Organisms coloniz-ing the catheter within the vessel may producebacteraemia without visible external infection. Theresident or transient cutaneous flora is the source ofinfection. The main risk factors are the length ofcatheterization, level of asepsis at insertion, andcontinuing catheter care.

1.2.5 Other nosocomial infections

These are the four most frequent and importantnosocomial infections, but there are many otherpotential sites of infection. For example:

● Skin and soft tissue infections: open sores (ulcers,burns and bedsores) encourage bacterial coloni-zation and may lead to systemic infection.

● Gastroenteritis is the most common nosocomialinfection in children, where rotavirus is a chiefpathogen: Clostridium difficile is the major cause ofnosocomial gastroenteritis in adults in developedcountries.

● Sinusitis and other enteric infections, infectionsof the eye and conjunctiva.

● Endometritis and other infections of the repro-ductive organs following childbirth.

1.3 Microorganisms

Many different pathogens may cause nosocomialinfections. The infecting organisms vary among dif-ferent patient populations, different health care set-tings, different facilities, and different countries.

1.3.1 Bacteria

These are the most common nosocomial pathogens.A distinction may be made between:

● Commensal bacteria found in normal flora ofhealthy humans. These have a significant protec-tive role by preventing colonization by patho-genic microorganisms. Some commensal bacteriamay cause infection if the natural host is com-promised. For example, cutaneous coagulase-negative staphylococci cause intravascular lineinfection and intestinal Escherichia coli are the mostcommon cause of urinary infection.

● Pathogenic bacteria have greater virulence, andcause infections (sporadic or epidemic) regardlessof host status. For example:

— Anaerobic Gram-positive rods (e.g. Clostridium)cause gangrene.

— Gram-positive bacteria: Staphylococcus aureus(cutaneous bacteria that colonize the skin andnose of both hospital staff and patients) causea wide variety of lung, bone, heart and blood-stream infections and are frequently resistantto antibiotics; beta-haemolytic streptococci arealso important.

— Gram-negative bacteria: Enterobacteriacae (e.g.Escherichia coli, Proteus, Klebsiella, Enterobacter,Serratia marcescens), may colonize sites when thehost defences are compromised (catheter in-sertion, bladder catheter, cannula insertion)and cause serious infections (surgical site, lung,bacteraemia, peritoneum infection). They mayalso be highly resistant.

— Gram-negative organisms such as Pseudomonasspp. are often isolated in water and dampareas. They may colonize the digestive tract ofhospitalized patients.

— Selected other bacteria are a unique risk inhospitals. For instance, Legionella species maycause pneumonia (sporadic or endemic)through inhalation of aerosols containing con-taminated water (air conditioning, showers,therapeutic aerosols).

1.3.2 Viruses

There is the possibility of nosocomial transmissionof many viruses, including the hepatitis B and Cviruses (transfusions, dialysis, injections, endoscopy),respiratory syncytial virus (RSV), rotavirus, and

7

enteroviruses (transmitted by hand-to-mouth con-tact and via the faecal-oral route). Other viruses suchas cytomegalovirus, HIV, Ebola, influenza viruses,herpes simplex virus, and varicella-zoster virus, mayalso be transmitted.

1.3.3 Parasites and fungi

Some parasites (e.g. Giardia lamblia) are transmittedeasily among adults or children. Many fungi andother parasites are opportunistic organisms andcause infections during extended antibiotic treatmentand severe immunosuppression (Candida albicans,Aspergillus spp., Cryptococcus neoformans, Cryptosporidium).These are a major cause of systemic infections amongimmunocompromised patients. Environmental con-tamination by airborne organisms such as Aspergil-lus spp. which originate in dust and soil is also aconcern, especially during hospital construction.

Sarcoptes scabies (scabies) is an ectoparasite which hasrepeatedly caused outbreaks in health care facilities.

1.4 Reservoirs and transmission

Bacteria that cause nosocomial infections can beacquired in several ways:

1. The permanent or transient flora of the patient(endogenous infection). Bacteria present in the nor-mal flora cause infection because of transmissionto sites outside the natural habitat (urinary tract),damage to tissue (wound) or inappropriate anti-biotic therapy that allows overgrowth (C. difficile,yeast spp.). For example, Gram-negative bacteriain the digestive tract frequently cause surgical siteinfections after abdominal surgery or urinary tractinfection in catheterized patients.

2. Flora from another patient or member of staff(exogenous cross-infection). Bacteria are transmittedbetween patients: (a) through direct contact be-tween patients (hands, saliva droplets or otherbody fluids), (b) in the air (droplets or dust con-taminated by a patient’s bacteria), (c) via staffcontaminated through patient care (hands, clothes,nose and throat) who become transient or per-manent carriers, subsequently transmitting bac-teria to other patients by direct contact duringcare, (d) via objects contaminated by the patient(including equipment), the staff’s hands, visitorsor other environmental sources (e.g. water, otherfluids, food).

3. Flora from the health care environment (endemicor epidemic exogenous environmental infections). Severaltypes of microorganisms survive well in the hos-pital environment:

— in water, damp areas, and occasionally in sterileproducts or disinfectants (Pseudomonas ,Acinetobacter, Mycobacterium)

— in items such as linen, equipment and sup-plies used in care; appropriate housekeepingnormally limits the risk of bacteria survivingas most microorganisms require humid or hotconditions and nutrients to survive

— in food

— in fine dust and droplet nuclei generated bycoughing or speaking (bacteria smaller than10 µm in diameter remain in the air for sev-eral hours and can be inhaled in the same wayas fine dust).

People are at the centre of the phenomenon:

● as main reservoir and source of microorganisms

● as main transmitter, notably during treatment

● as receptor for microorganisms, thus becoming anew reservoir.

References

1. Mayon-White R et al. An international survey ofthe prevalence of hospital-acquired infection.J Hosp Infect, 1988, 11 (suppl A):43–48.

2. Emmerson AM et al. The second national preva-lence survey of infection in hospitals — overviewof the results. J Hosp Infect, 1996, 32:175–190.

3. Enquête nationale de prévalence des infectionsnosocomiales. Mai–Juin 1996. Comité techniquenational des infections nosocomiales. BulletinÈpidémiologique Hebdomadaire, 1997, No 36.

4. Gastmeier P et al. Prevalence of nosocomial in-fections in representative German hospitals. J HospInfect, 1998, 38:37–49.

5. Vasque J, Rossello J, Arribas JL. Prevalence ofnosocomial infections in Spain: EPINE study1990–1997. EPINE Working Group. J Hosp Infect,1999, 43 Suppl:S105–S111.

CHAPTER I. EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS


8

6. Danchaivijitr S, Tangtrakool T, Chokloikaew S. Thesecond Thai national prevalence study on noso-comial infections 1992. J Med Assoc Thai, 1995, 78Suppl 2:S67–S72.

7. Kim JM et al. Multicentre surveillance study fornosocomial infections in major hospitals inKorea. Am J Infect Control, 2000, 28:454–458.

8. Raymond J, Aujard Y, European Study Group.Nosocomial Infections in Pediatric Patients: AEuropean, Multicenter Prospective Study. InfectControl Hosp Epidemiol, 2000, 21:260–263.

9. Pittet D et al. Prevalence and risk factors for no-socomial infections in four university hospitalsin Switzerland. Infect Control Hosp Epidemiol, 1999,20:37–42.

10. Gikas A et al. Repeated multi-centre prevalencesurveys of hospital-acquired infection in Greekhospitals. J Hosp Infect, 1999, 41:11–18.

11. Scheel O, Stormark M. National prevalence sur-vey in hospital infections in Norway. J Hosp Infect,1999, 41:331–335.

12. Valinteliene R, Jurkuvenas V, Jepsen OB. Preva-lence of hospital-acquired infection in a Lithua-nian hospital. J Hosp Infect, 1996, 34:321–329.

13. Orrett FA, Brooks PJ, Richardson EG. Nosocomialinfections in a rural regional hospital in a devel-oping country: infection rates by site, service, cost,and infection control practices. Infect Control HospEpidemiol, 1998, 19:136–140.

14. Garner JS et al. CDC definitions for nosocomialinfections, 1988. Am J Infect Control, 1988, 16:128–140.

15. Horan TC et al. CDC definitions of nosocomialsurgical site infections, 1992: a modification ofCDC definition of surgical wound infections. AmJ Infect Control, 1992, 13:606–608.

16. McGeer A et al. Definitions of infection for sur-veillance in long-term care facilities. Am J InfectControl, 1991, 19:1–7.

17. Girard R. Guide technique d’hygiène hospitalière. Alger,Institut de la Santé publique et Lyon, FondationMarace Mérieux, 1990.

18. Cruse PJE, Ford R. The epidemiology of woundinfection. A 10 year prospective study of 62,939wounds. Surg Clin North Am, 1980, 60:27–40.

19. Horan TC et al. Nosocomial infections in surgicalpatients in the United States, 1986–1992 (NNIS).Infect Control Hosp Epidemiol, 1993, 14:73–80.

20. Hajjar J et al. Réseau ISO Sud-Est: un an de sur-veillance des infections du site opératoire. Bulle-tin Èpidémiologique Hebdomadaire, 1996, No 42.

21. Brachman PS et al. Nosocomial surgical infec-tions: incidence and cost. Surg Clin North Am, 1980,60:15–25.

22. Fabry J et al. Cost of nosocomial infections: analy-sis of 512 digestive surgery patients. World J Surg,1982, 6:362–365.

23. Prabhakar P et al. Nosocomial surgical infections:incidence and cost in a developing country. Am JInfect Control, 1983, 11:51–56.

24. Kirkland KB et al. The impact of surgical-site in-fections in the 1990’s: attributable mortality, ex-cess length of hospitalization and extra costs. InfectControl Hosp Epidemiol, 1999, 20:725–730.

25. Nosocomial infections rates for interhospital com-parison: limitations and possible solutions — Areport from NNIS System. Infect Control HospEpidemiol, 1991, 12:609–621.

9

CHAPTER II

Infection control programmes

Professional and academic organizations must alsobe involved in this programme.

2.2 Hospital programmes

The major preventive effort should be focused inhospitals and other health care facilities (2). Risk pre-vention for patients and staff is a concern of every-one in the facility, and must be supported at thelevel of senior administration. A yearly work plan toassess and promote good health care, appropriateisolation, sterilization, and other practices, staff train-ing, and epidemiological surveillance should be de-veloped. Hospitals must provide sufficient resourcesto support this programme.

2.2.1 Infection Control Committee

An Infection Control Committee provides a forumfor multidisciplinary input and cooperation, andinformation sharing. This committee should includewide representation from relevant programmes: e.g.management, physicians, other health care workers,clinical microbiology, pharmacy, central supply,maintenance, housekeeping, training services. Thecommittee must have a reporting relationshipdirectly to either administration or the medical staffto promote programme visibility and effectiveness.In an emergency (such as an outbreak), this com-mittee must be able to meet promptly. It has thefollowing tasks:

● to review and approve a yearly programme ofactivity for surveillance and prevention

● to review epidemiological surveillance data andidentify areas for intervention

● to assess and promote improved practice at alllevels of the health facility

● to ensure appropriate staff training in infectioncontrol and safety

Prevention of nosocomial infections is the respon-sibility of all individuals and services providing

health care. Everyone must work cooperatively toreduce the risk of infection for patients and staff.This includes personnel providing direct patient care,management, physical plant, provision of materialsand products, and training of health workers. Infec-tion control programmes (1) are effective providedthey are comprehensive and include surveillance andprevention activities, as well as staff training. Theremust also be effective support at the national andregional levels.

2.1 National or regional programmes

The responsible health authority should develop anational (or regional) programme to support hospi-tals in reducing the risk of nosocomial infections.Such programmes must:

● set relevant national objectives consistent withother national health care objectives

● develop and continually update guidelines forrecommended health care surveillance, preven-tion, and practice

● develop a national system to monitor selectedinfections and assess the effectiveness of inter-ventions

● harmonize initial and continuing training pro-grammes for health care professionals

● facilitate access to materials and products essen-tial for hygiene and safety

● encourage health care establishments to monitornosocomial infections, with feedback to the pro-fessionals concerned.

The health authority should designate an agency tooversee the programme (a ministerial department,institution or other body), and plan national activi-ties with the help of a national expert committee.


10

● to review risks associated with new technologies,and monitor infectious risks of new devices andproducts, prior to their approval for use

● to review and provide input into investigation ofepidemics

● to communicate and cooperate with other com-mittees of the hospital with common interests suchas Pharmacy and Therapeutics or AntimicrobialUse Committee, Biosafety or Health and SafetyCommittees, and Blood Transfusion Committee.

2.2.2 Infection control professionals (infectioncontrol team)

Health care establishments must have access to spe-cialists in infection control, epidemiology, andinfectious disease including infection control physi-cians and infection control practitioners (usuallynurses) (2). In some countries, these professionals arespecialized teams working for a hospital or a groupof health care establishments; they may be admin-istratively part of another unit, (e.g. microbiologylaboratory, medical or nursing administration, pub-lic health services). The optimal structure will varywith the type, needs, and resources of the facility.The reporting structure must, however, ensure theinfection control team has appropriate authority tomanage an effective infection control programme.In large facilities, this will usually mean a direct re-porting relationship with senior administration.

The infection control team or individual is respon-sible for the day-to-day functions of infection con-trol, as well as preparing the yearly work plan forreview by the infection control committee and ad-ministration. These individuals have a scientific andtechnical support role: e.g. surveillance and research,developing and assessing policies and practicalsupervision, evaluation of material and products,control of sterilization and disinfection, implemen-tation of training programmes. They should alsosupport and participate in research and assessmentprogrammes at the national and internationallevels.

2.2.3 Infection control manual

A nosocomial infection prevention manual (3), com-piling recommended instructions and practices forpatient care, is an important tool. The manual shouldbe developed and updated by the infection controlteam, with review and approval by the committee.

It must be made readily available for patient carestaff, and updated in a timely fashion.

2.3 Infection control responsibility

2.3.1 Role of hospital management

The administration and/or medical management ofthe hospital must provide leadership by supportingthe hospital infection programme. They are respon-sible for:

● establishing a multidisciplinary Infection ControlCommittee

● identifying appropriate resources for a programmeto monitor infections and apply the most appro-priate methods for preventing infection

● ensuring education and training of all staffthrough support of programmes on the preven-tion of infection in disinfection and sterilizationtechniques

● delegating technical aspects of hospital hygieneto appropriate staff, such as:

— nursing

— housekeeping

— maintenance

— clinical microbiology laboratory

● periodically reviewing the status of nosocomialinfections and effectiveness of interventions tocontain them

● reviewing, approving, and implementing policiesapproved by the Infection Control Committee

● ensuring the infection control team has authorityto facilitate appropriate programme function

● participating in outbreak investigation.

2.3.2 Role of the physician

Physicians have unique responsibilities for the pre-vention and control of hospital infections:

● by providing direct patient care using practiceswhich minimize infection

● by following appropriate practice of hygiene(e.g. handwashing, isolation)

● serving on the Infection Control Committee

● supporting the infection control team.

11

Specifically, physicians are responsible for:

● protecting their own patients from other infectedpatients and from hospital staff who may be in-fected

● complying with the practices approved by theInfection Control Committee

● obtaining appropriate microbiological specimenswhen an infection is present or suspected

● notifying cases of hospital-acquired infection tothe team, as well as the admission of infected pa-tients

● complying with the recommendations of the An-timicrobial Use Committee regarding the use ofantibiotics

● advising patients, visitors and staff on techniquesto prevent the transmission of infection

● instituting appropriate treatment for any infec-tions they themselves have, and taking steps toprevent such infections being transmitted to otherindividuals, especially patients.

2.3.3 Role of the microbiologist (4)

The microbiologist is responsible for:

● handling patient and staff specimens to maximizethe likelihood of a microbiological diagnosis

● developing guidelines for appropriate collection,transport, and handling of specimens

● ensuring laboratory practices meet appropriatestandards

● ensuring safe laboratory practice to prevent in-fections in staff

● performing antimicrobial susceptibility testingfollowing internationally recognized methods, andproviding summary reports of prevalence of re-sistance

● monitoring sterilization, disinfection and theenvironment where necessary

● timely communication of results to the InfectionControl Committee or the hygiene officer

● epidemiological typing of hospital microorgan-isms where necessary.

2.3.4 Role of the hospital pharmacist (5)

The hospital pharmacist is responsible for:

● obtaining, storing and distributing pharmaceuti-cal preparations using practices which limitpotential transmission of infectious agents topatients

● dispensing anti-infectious drugs and maintain-ing relevant records (potency, incompatibility,conditions of storage and deterioration)

● obtaining and storing vaccines or sera, and mak-ing them available as appropriate

● maintaining records of antibiotics distributed tothe medical departments

● providing the Antimicrobial Use Committee andInfection Control Committee with summary re-ports and trends of antimicrobial use

● having available the following information ondisinfectants, antiseptics and other anti-infectiousagents:

— active properties in relation to concentration,temperature, length of action, antibiotic spec-trum

— toxic properties including sensitization orirritation of the skin and mucosa

— substances that are incompatible with anti-biotics or reduce their potency

— physical conditions which unfavourably affectpotency during storage: temperature, light,humidity

— harmful effects on materials.

The hospital pharmacist may also participate in thehospital sterilization and disinfection practicesthrough:

● participation in development of guidelines forantiseptics, disinfectants, and products used forwashing and disinfecting the hands

● participation in guideline development for reuseof equipment and patient materials

● participation in quality control of techniques usedto sterilize equipment in the hospital includingselection of sterilization equipment (type ofappliances) and monitoring.

CHAPTER II. INFECTION CONTROL PROGRAMMES


12

2.3.5 Role of the nursing staff

Implementation of patient care practices for infec-tion control is the role of the nursing staff. Nursesshould be familiar with practices to prevent theoccurrence and spread of infection, and maintainappropriate practices for all patients throughout theduration of their hospital stay.

The senior nursing administrator is responsible for:

● participating in the Infection Control Committee

● promoting the development and improvement ofnursing techniques, and ongoing review of asep-tic nursing policies, with approval by the Infec-tion Control Committee

● developing training programmes for members ofthe nursing staff

● supervising the implementation of techniques forthe prevention of infections in specialized areassuch as the operating suite, the intensive care unit,the maternity unit and newborns

● monitoring of nursing adherence to policies.

The nurse in charge of a ward is responsible for:

● maintaining hygiene, consistent with hospitalpolicies and good nursing practice on the ward

● monitoring aseptic techniques, including hand-washing and use of isolation

● reporting promptly to the attending physician anyevidence of infection in patients under the nurse’scare

● initiating patient isolation and ordering culturespecimens from any patient showing signs of acommunicable disease, when the physician is notimmediately available

● limiting patient exposure to infections from visi-tors, hospital staff, other patients, or equipmentused for diagnosis or treatment

● maintaining a safe and adequate supply of wardequipment, drugs and patient care supplies.

The nurse in charge of infection control is a member of theinfection control team and responsible for :

● identifying nosocomial infections

● investigation of the type of infection and infect-ing organism

● participating in training of personnel

● surveillance of hospital infections

● participating in outbreak investigation

● development of infection control policy andreview and approval of patient care policiesrelevant to infection control

● ensuring compliance with local and national regu-lations

● liaison with public health and with other facili-ties where appropriate

● providing expert consultative advice to staff healthand other appropriate hospital programmes inmatters relating to transmission of infections.

2.3.6 Role of the central sterilization service

A central sterilization department serves all hospitalareas, including the operating suite. An appropri-ately qualified individual must be responsible formanagement of the programme. Responsibility forday-to-day management may be delegated to a nurseor other individual with appropriate qualifications,experience, and knowledge of medical devices.

The responsibilities of the central sterilization service areto clean, decontaminate, test, prepare for use, steri-lize, and store aseptically all sterile hospital equip-ment. It works in collaboration with the InfectionControl Committee and other hospital programmesto develop and monitor policies on cleaning anddecontamination of:

● reusable equipment

● contaminated equipment

including

— wrapping procedures, according to the typeof sterilization

— sterilization methods, according to the type ofequipment

— sterilization conditions (e.g. temperature, du-ration, pressure, humidity) (see Chapter V).

The director of this service must:

● oversee the use of different methods — physical,chemical, and bacteriological — to monitor thesterilization process

● ensure technical maintenance of the equipmentaccording to national standards and manufactur-ers’ recommendations

● report any defect to administration, maintenance,infection control and other appropriate personnel

13

● maintain complete records of each autoclave run,and ensure long-term availability of records

● collect or have collected, at regular intervals, alloutdated sterile units

● communicate, as needed, with the InfectionControl Committee, the nursing service, the op-erating suite, the hospital transport service,pharmacy service, maintenance, and other appro-priate services.

2.3.7 Role of the food service (see Chapter VIII)

The director of food services must be knowledgeable infood safety, staff training, storage and preparationof foodstuffs, job analysis, and use of equipment.

The head of catering services is responsible for:

● defining the criteria for the purchase of foodstuffs,equipment use, and cleaning procedures to main-tain a high level of food safety

● ensuring that the equipment used and all work-ing and storage areas are kept clean

● issuing written policies and instructions forhandwashing, clothing, staff responsibilities anddaily disinfection duties

● ensuring that the methods used for storing, pre-paring and distributing food will avoid contami-nation by microorganisms

● issuing written instructions for the cleaning ofdishes after use, including special considerationsfor infected or isolated patients where appropri-ate

● ensuring appropriate handling and disposal ofwastes

● establishing programmes for training staff in foodpreparation, cleanliness, and food safety

● establishing a Hazard Analysis of Critical ControlPoints (HACCP) programme, if required.

2.3.8 Role of the laundry service (see Chapter VIII)

The laundry is responsible for:

● selecting fabrics for use in different hospitalareas, developing policies for working clothes ineach area and group of staff, and maintainingappropriate supplies

● distribution of working clothes and, if necessary,managing changing rooms

● developing policies for the collection and trans-port of dirty linen

● defining, where necessary, the method for disin-fecting infected linen, either before it is taken tothe laundry or in the laundry itself

● developing policies for the protection of cleanlinen from contamination during transport fromthe laundry to the area of use

● developing criteria for selection of site of laundryservices:

— ensuring appropriate flow of linen, separationof “clean” and “dirty” areas

— recommending washing conditions (e.g. tem-perature, duration)

— ensuring safety of laundry staff throughprevention of exposure to sharps or laundrycontaminated with potential pathogens.

2.3.9 Role of the housekeeping service (see 5.3)

The housekeeping service is responsible for the regu-lar and routine cleaning of all surfaces and main-taining a high level of hygiene in the facility. Incollaboration with the Infection Control Committeeit is responsible for :

● classifying the different hospital areas by varyingneed for cleaning

● developing policies for appropriate cleaning tech-niques

— procedure, frequency, agents used, etc., for eachtype of room, from highly contaminated tothe most clean, and ensuring that these prac-tices are followed

● developing policies for collection, transport anddisposal of different types of waste (e.g. contain-ers, frequency)

● ensuring that liquid soap and paper towel dis-pensers are replenished regularly

● informing the maintenance service of any build-ing problems requiring repair: cracks, defects inthe sanitary or electrical equipment, etc.

● caring for flowers and plants in public areas

● pest control (insects, rodents)



14

● providing appropriate training for all new staffmembers and, periodically, for other employees,and specific training when a new technique isintroduced

● establishing methods for the cleaning and disin-fection of bedding (e.g. mattresses, pillows)

● determining the frequency for the washing ofcurtains, screening curtains between beds, etc.

● reviewing plans for renovations or new furniture,including special patient beds, to determine fea-sibility of cleaning.

There should be a continuing programme for stafftraining.This programme should stress personalhygiene, the importance of frequent and carefulwashing of hands, and cleaning methods (e.g.sequence of rooms, correct use of equipment, dilu-tion of cleaning agents, etc.). Staff must also under-stand causes of contamination of premises, and howto limit this, including the method of action of dis-infectants. Cleaning staff must know to contact staffhealth if they have a personal infection, especiallyinfections of the skin, digestive tract and respiratorytract.

2.3.10 Role of maintenance

Maintenance is responsible for:

● collaborating with housekeeping, nursing staff orother appropriate groups in selecting equipmentand ensuring early identification and prompt cor-rection of any defect

● inspections and regular maintenance of theplumbing, heating, and refrigeration equipment,and electrical fittings and air conditioning; recordsshould be kept of this activity

● developing procedures for emergency repairs inessential departments

● ensuring environmental safety outside the hos-pital, e.g. waste disposal, water sources.

Additional special duties include:

— participation in the choice of equipment ifmaintenance of the equipment requires tech-nical assistance

— inspection, cleaning and regular replacementof the filters of all appliances for ventilationand humidifiers

— testing autoclaves (temperature, pressure,vacuum, recording mechanism) and regularmaintenance (cleaning the inner chamber,emptying the tubes)

— monitoring the recording thermometers ofrefrigerators in pharmacy stores, laboratories,the blood bank and kitchens

— regularly inspecting all surfaces — walls, floors,ceilings — to ensure they are kept smooth andwashable

— repairing any opening or crack in partitionwalls or window frames

— maintaining hydrotherapy appliances

— notifying infection control of any anticipatedinterruption of services such as plumbing orair conditioning.

2.3.11 Role of the infection control team(hospital hygiene service)

The infection control programme is responsible foroversight and coordination of all infection controlactivities to ensure an effective programme.

The hospital hygiene service is responsible for:

● organizing an epidemiological surveillance pro-gramme for nosocomial infections

● participating with pharmacy in developing a pro-gramme for supervising the use of anti-infectivedrugs

● ensuring patient care practices are appropriate tothe level of patient risk

● checking the efficacy of the methods of disinfec-tion and sterilization and the efficacy of systemsdeveloped to improve hospital cleanliness

● participating in development and provision ofteaching programmes for the medical, nursing,and allied health personnel, as well as all othercategories of staff

● providing expert advice, analysis, and leadershipin outbreak investigation and control

● participating in the development and operationof regional and national infection control initia-tives

● the hospital hygiene service may also provideassistance for smaller institutions, and undertakeresearch in hospital hygiene and infection con-

15

trol at the facility, local, national, or internationallevel.

References

1. Haley RW et al. The efficacy of infection surveil-lance and control programs in preventing noso-comial infections in US hospitals. Am J. Epidem,1985, 121:182–205.

2. Schechler WE et al. Requirements for infrastruc-ture and essential activities of infection controland epidemiology in hospitals: a consensus panelreport. Society of Healthcare Epidemiology ofAmerica. Infect Control Hosp Epidemiol, 1998, 19:114–124.

3. Savey A, Troadec M. Le Manuel du CLIN, un outilpour une demande de qualité — CoordinationC.CLIN Sud-Est. Hygiènes, 2001, IX:73–162.

4. Emory TG, Gaynes RP. An overview of nosoco-mial infections including the role of the micro-biology laboratory. Clin Microbiol Rev, 1993,6:428–442.

5. American Society of Health System Pharmacists.ASHP statement on the pharmacist’s role ininfection control. Am J Hosp Pharm, 1986, 43:2006–2008.



16

CHAPTER III

Nosocomial infection surveillance

● to identify the need for new or intensified pre-vention programmes, and evaluate the impact ofprevention measures

● to identify possible areas for improvement inpatient care, and for further epidemiological stud-ies (i.e. risk factor analysis).

3.2 Strategy

A surveillance system must meet the followingcriteria (Table 1):

● simplicity, to minimize costs and workload, andpromote unit participation by timely feedback

● flexibility, to allow changes when appropriate

● acceptability (e.g. evaluated by the level of par-ticipation, data quality)

● consistency (use standardized definitions, meth-odology)

● sensitivity, although a case-finding method withlow sensitivity can be valid in following trends,as long as sensitivity remains consistent over timeand cases identified are representative

● specificity, requiring precise definitions andtrained investigators.

The nosocomial infection rate in patients in afacility is an indicator of quality and safety of

care. The development of a surveillance process tomonitor this rate is an essential first step to identifylocal problems and priorities, and evaluate the ef-fectiveness of infection control activity. Surveillance,by itself, is an effective process to decrease the fre-quency of hospital-acquired infections (1,2,3).

● improvements in health care with increasedquality and safety

but

● changes in care with new techniques, newpathogens or changes in resistance, increasedpatient acuity, ageing population, etc.

=● need for active surveillance to monitor changing

infectious risks

and

● identify needs for changes in control measures.

3.1 Objectives

The ultimate aim is the reduction of nosoco-mial infections, and their costs.

The specific objectives of a surveillance programmeinclude:

● to improve awareness of clinical staff and otherhospital workers (including administrators) aboutnosocomial infections and antimicrobial resist-ance, so they appreciate the need for preventiveaction

● to monitor trends: incidence and distribution ofnosocomial infections, prevalence and, wherepossible, risk-adjusted incidence for intra- andinter-hospital comparisons

TABLE 1. Desired characteristics of a nosocomialinfection surveillance system*

Characteristics of the system:

• timeliness, simplicity, flexibility• acceptability, reasonable cost• representativeness (or exhaustiveness)

Quality of the data provided:

• sensitivity, specificity• predictive value (positive and negative)• usefulness, in relation to the goals of the surveillance

(quality indicators)

* Adapted from Thacker SB, 1988 (4).

17

CHAPTER III. NOSOCOMIAL INFECTION SURVEILLANCE

The extent to which these characteristics are met willvary among different institutions.

3.2.1 Implementation at the hospital level

Ensuring a valid surveillance system is an impor-tant hospital function. There must be specific objec-tives (for units, services, patients, specific care areas)and defined time periods of surveillance for allpartners: e.g. clinical units and laboratory staff,infection control practitioner (ICP)/nurse, and direc-tor, administration.

Initially, discussion should identify the informationneeds, and the potential for the chosen indicators tosupport implementation of corrective measures (whator who is going to be influenced by the data). Thisdiscussion will include:

● the patients and units to be monitored (definedpopulation)

● the type of infections and relevant informationto be collected for each case (with precise defini-tions)

● the frequency and duration of monitoring

● methods for data collection

● methods for data analysis, feedback, and dissemi-nation

● confidentiality and anonymity.

The surveillance programme must report to hospi-tal administration, usually through the InfectionControl Committee (ICC), and must have a dedicatedbudget to support its operation.

3.2.2 Implementation at the network (regionalor national) level

Hospitals should share nosocomial infection data,on a confidential basis, with a network of similarfacilities to support standards development for in-ter-facility comparisons (5), and to detect trends.Local, regional, national or international networksmay be developed. The advantages include:

● technical and methodological assistance

● reinforcing compliance to existing guidelines andclinical practices

● evaluating the importance of surveillance (morelegitimacy) to encourage participation

● facilitating the exchange of experiences andsolutions

● promoting epidemiological research, includinganalysis of the impact of interventions

● assisting nation/states in scope and magnitudeestimates to help with resource allocation nation-ally and internationally

● the key advantage: possibility of developing validinter-hospital comparisons using standardizedmethods and adjusted rates.

3.3 Methods

Simply counting infected patients (numerator) pro-vides only limited information which may be diffi-cult to interpret. Further data are necessary to fullydescribe the problem on a population basis, to quan-tify its importance, to interpret variations, and topermit comparisons. Risk factor analysis requiresinformation for both infected and non-infectedpatients. Infection rates, as well as risk-adjusted rates,can then be calculated.

“Passive surveillance” with reporting by individualsoutside the infection control team (laboratory-basedsurveillance, extraction from medical records post-discharge, infection notification by physicians ornurses) is of low sensitivity. Therefore some form ofactive surveillance for infections (prevalence orincidence studies) is recommended (Table 2).

FIGURE 1. “Surveillance is a circular process”

3.Prevention: decisions and

corrective actions

2.Feedback and

dissemination: dataanalysis,

interpretation,comparisons,

discussion

4.Evaluation of the

impact onnosocomialinfections by

surveillance (trends)or other studies

1.Implementation of surveillance:

goals definition, surveillanceprotocol data collection

The optimal method (Figure 1) is dependent on hos-pital characteristics, the desired objectives, resourcesavailable (computers, investigators) and the level ofsupport of the hospital staff (both administrative andclinical).


18

3.3.1 Prevalence study (cross-sectional/transverse)

Infections in all patients hospitalized at a given pointin time are identified (point prevalence) in the en-tire hospital, or on selected units. Typically, a teamof trained investigators visits every patient of thehospital on a single day, reviewing medical and nurs-ing charts, interviewing the clinical staff to identifyinfected patients, and collecting risk factor data. Theoutcome measure is a prevalence rate.

Prevalence rates are influenced by duration of thepatient’s stay (infected patients stay longer, leadingto an overestimation of patient’s risk of acquiringan infection) and duration of infections.

Another problem is determining whether an infec-tion is still “active” on the day of the study.

In small hospitals, or small units, the number ofpatients may be too few to develop reliable rates, orto allow comparisons with statistical significance.

A prevalence study is simple, fast, and relatively in-expensive. The hospital-wide activity increasesawareness of nosocomial infection problems amongclinical staff, and increases the visibility of the in-fection control team. It is useful when initiating asurveillance programme to assess current issues forall units, for all kinds of infections, and in all pa-tients, before proceeding to a more focused continu-ing active surveillance programme. Repeatedprevalence surveys can be useful to monitor trendsby comparing rates in a unit, or in a hospital, overtime.

3.3.2 Incidence study (continuous/longitudinal)

Prospective identification of new infections (incidencesurveillance) requires monitoring of all patientswithin a defined population for a specified time pe-riod. Patients are followed throughout their stay, andsometimes after discharge (e.g. post-discharge sur-veillance for surgical site infections). This type of

surveillance provides attack rates, infection ratio andincidence rates (Table 3). It is more effective indetecting differences in infection rates, to followtrends, to link infections to risk factors, and forinter-hospital and inter-unit comparisons (6).

This surveillance is more labour-intensive than aprevalence survey, more time-consuming, and costly.Therefore, it is usually undertaken only for selectedhigh-risk units on an ongoing basis (i.e. in intensivecare units), or for a limited period, focusing onselected infections and specialties (i.e. 3 months insurgery) (7,8,9,10).

Recent trends in “targeted surveillance” include:

● Site-oriented surveillance: priorities will be tomonitor frequent infections with significant im-pact in mortality, morbidity, costs (e.g. extra-hospital days, treatment costs), and which maybe avoidable.

Common priority areas are:

— ventilator-associated pneumonia (a high mor-tality rate)

— surgical site infections (first for extra-hospitaldays and cost)

— primary (intravascular line) bloodstream in-fections (high mortality)

— multiple-drug resistant bacteria (e.g. methicil-lin-resistant Staphylococcus aureus, Klebsiella spp.with extended-spectrum beta-lactamase).

This surveillance is primarily laboratory-based.The laboratory also provides units with regularreports on distribution of microorganisms isolated,and antibiotic susceptibility profiles for the mostfrequent pathogens.

● Unit-oriented surveillance: efforts can focus onhigh-risk units such as intensive care units, sur-gical units, oncology/haematology, burn units,neonatalogy, etc.

● Priority-oriented surveillance: surveillance un-dertaken for a specific issue of concern to thefacility (i.e. urinary tract infections in patients withurinary catheters in long-term care facilities).

While surveillance is focused in high-risk sectors,some surveillance activity should occur for therest of the hospital. This may be most efficientlyperformed on a rotating basis (laboratory-basedor repeated prevalence studies).

TABLE 2. Key points in the process of surveillancefor nosocomial infection rates

• Active surveillance (prevalence and incidence studies)

• Targeted surveillance (site-, unit-, priority-oriented)

• Appropriately trained investigators

• Standardized methodology

• Risk-adjusted rates for comparisons

19


TABLE 3. Prevalence and incidence rates (11,12)

Prevalence rate Examples

Number of infected patients* at the time of study / Prevalence (%) of nosocomial infections (NI)Number of patients observed at the same time for 100 hospitalized patients

X100 Prevalence (%) of urinary tract infections (UTI)(*or number of infections) for 100 hospitalized patients

Number of infected patients at the time of the study / Prevalence (%) of UTI for 100 patients withNumber of patients exposed at the same time a urinary catheter

X100

Attack rate (cumulative incidence rate)

Number of new infections acquired in a period / Attack rate (%) of UTI for 100 hospitalized patientsNumber of patients observed in the same period

X100

Number of new infections acquired in a period / Attack rate (%) of surgical site infections (SSI)Number of patients exposed in the same period for 100 operated patients

X100

Incidence rate

Number of new nosocomial infections acquired Incidence of bloodstream infection (BSI)in a period / for 1000 patient-days

Total of patient-days for the same periodX1000

Number of new device-associated nosocomial Incidence of ventilator-associated pneumoniainfections in a period / for 1000 ventilation-days

Total device-days for the same periodX1000

3.3.3 Calculating rates

Rates are obtained by dividing a numerator (numberof infections or infected patients observed) by adenominator (population at risk, or number ofpatient-days of risk). The frequency of infection canbe estimated by prevalence and incidence indica-tors (Table 3).

For multiple-drug resistant bacteria surveillance, thethree main indicators used are :

● percentage of antimicrobial resistant strains withinisolates of a species, e.g. percentage of Staphylococ-cus aureus resistant to methicillin (MRSA)

● attack rate (i.e. number of MRSA/100 admissions)

● incidence rate (MRSA/1000 patient-days).

For both prevalence and incidence rates, either theglobal population under surveillance, or onlypatients with a specific risk exposure, may be thedenominator.

Attack rates can be estimated by the calculation of asimplified infection ratio using an estimate of thedenominator for the same period of time (i.e. numberof admissions or discharges, number of surgical pro-cedures).

Incidence rates are encouraged as they take into ac-count the length of exposure, or the length of stay(and/or follow-up) of the patient; this gives a betterreflection of risk and facilitates comparisons. Eitherpatient-day rates or device-associated rates can beused.

3.4 Organization for efficient surveillance

Nosocomial infection surveillance includes data col-lection, analysis and interpretation, feedback lead-ing to interventions for preventive action, andevaluation of the impact of these interventions (seeFigure 1 earlier in this chapter). The director (physi-cian and/or nurse from the infection control team,


20

the unit under surveillance, or from the InfectionControl Committee) must be a trained professionalspecifically responsible for surveillance, includingtraining of personnel for data collection. A writtenprotocol must describe the methods to be used, thedata to be collected (e.g. patient inclusion criteria,definitions), the analysis that can be expected, andpreparation and timing of reports (13).

3.4.1 Data collection and analysis

3.4.1.1 Sources

Data collection requires multiple sources of infor-mation as no method, by itself, is sensitive enoughto ensure data quality. Trained data extractors (train-ing should be organized by the infection control teamor the supervisor) performing active surveillance willincrease the sensitivity for identifying infections.Techniques for case-finding include:

● Ward activity: looking for clues such as:

— the presence of devices or procedures knownto be a risk for infection (indwelling urinaryand intravascular catheters, mechanical ven-tilation, surgical procedures)

— record of fever or other clinical signs consist-ent with infection

— antimicrobial therapy

— laboratory tests

— medical and nursing chart review.

● Laboratory reports: isolation of microorgan-isms potentially associated with infection, anti-microbial resistance patterns, serological tests.Microbiology laboratory reports have low sensi-tivity because cultures are not obtained for allinfections, specimens may not be appropriate,some infectious pathogens may not be isolated(e.g. virus), and the isolation of a potential patho-gen may represent colonization rather thaninfection (e.g. for surgical site infections, pneu-monia). Laboratory reports are, however, reliablefor urinary tract infection, bloodstream infections,and multiple-drug resistant bacteria surveillance,because the definitions for these are essentiallymicrobiological.

● Other diagnostic tests: e.g. white blood counts,diagnostic imaging, autopsy data.

● Discussion of cases with the clinical staff dur-ing periodic ward visits.

Continuing collaboration among infection controlstaff, the laboratory, and clinical units will facilitatean exchange of information and improve data qual-ity (14). The patient is monitored throughout thehospital stay, and in some cases (e.g. for surgical siteinfections), surveillance includes the post-dischargeperiod (15). The progressive reduction of the aver-age length of stay with recent changes in health caredelivery increases the importance of identifying post-discharge infections.

3.4.1.2 Data elements

Some examples of data collection forms for a preva-lence study and for surgical site infection surveil-lance are given in Figures 2 and 3. One form iscompleted for each patient. Simple, validated, andstandardized definitions (16,17) are essential for cred-ibility of the surveillance system and to ensure dataquality. A complete guide for data collection shouldinclude:

● patient inclusion criteria

● precise definitions for each variable to be collected(not only definitions for infections)

● lists of codes for each variable, including specificcodes for missing data.

This data collection guide is also useful in trainingdata extractors.

The information to be collected should include:

● administrative data (e.g. hospital number, admis-sion date)

● additional information describing demographicrisk factors (e.g. age, gender, severity of underly-ing illness, primary diagnosis, immunologicalstatus) and interventions (e.g. device exposure,surgical procedure, treatments) for infected andfor non-infected patients

● presence or absence of infection: date of onset,site of infection, microorganisms isolated, andantimicrobial susceptibility.

Data validation is essential to ensure correct inter-pretation and meaningful comparisons. Validationis a continuous process which may incorporate vari-ous methods:

● before data input, information validated by asecond extractor

● if computerized data collection is used, the soft-ware should include input checks (each variable

21


FIGURE 2. Example of a minimum data collection form for prevalence study

Date (dd/mm/yy) __ __ __ __ __ __

Hospital __ __

Unit __ __

Unit specialty __ __

Patient

Patient identification __ __ __ __ __

Age (years) __ __ __

Gender ■■ male ■■ female __

Date of admission in the hospital (dd/mm/yy) __ __ __ __ __ __

Patient exposure

Surgical procedure (during the last month) ■■ Yes ■■ No __

Urinary catheter ■■ Yes ■■ No __

Mechanical ventilation ■■ Yes ■■ No __

Intravascular catheter ■■ Yes ■■ No __

Antibiotic ■■ Yes ■■ No __

If yes, prescription for

■■ Prophylaxis ■■ Therapy ■■ Other/unknown __

Nosocomial infection

■■ Yes ■■ No __

If yes, fill the following items

Surgical site infection ■■ Yes ■■ No __

Urinary tract infection ■■ Yes ■■ No __

Bloodstream infection ■■ Yes ■■ No __

Pneumonia ■■ Yes ■■ No __

Other respiratory infection ■■ Yes ■■ No __

Line-related infection ■■ Yes ■■ No __

Other nosocomial infection ■■ Yes ■■ No __


22

FIGURE 3. Example of a data collection form for surgical site infection surveillance

Hospital __ __

Unit __ __

Patient

Patient identification __ __ __

Age (years) __ __ __

Gender ■■ male ■■ female __

Date of admission (in the hospital) (dd/mm/yy) __ __ __ __ __ __

Date of discharge (from the unit) (dd/mm/yy) __ __ __ __ __ __

Operation

Date of operation (dd/mm/yy) __ __ __ __ __ __

Main procedure (code)

Wound class ■■ Clean ■■ Contaminated

■■ Clean-contaminated ■■ Dirty/infected __

ASA score ■■ 1 ■■ 2 ■■ 3 ■■ 4 ■■ 5 __

Duration of operation (minutes) __ __ __

Urgent ■■ Yes ■■ No __

Prosthesis/implant ■■ Yes ■■ No __

Multiple procedures ■■ Yes ■■ No __

Coeliosurgery ■■ Yes ■■ No __

Antibiotics

Antimicrobial prophylaxis ■■ Yes ■■ No __

Starting date (dd/mm/yy) __ __ __ __ __ __

Duration (days) __ __

Surgical site infection

Surgical site infection ■■ Yes ■■ No __

Date of infection (dd/mm/yy) __ __ __ __ __ __

Infection site ■■ superficial ■■ deep ■■ organ/space __

Microorganism 1 __ __ __

Microorganism 2 __ __ __

Date of last contact (dd/mm/yy) __ __ __ __ __ __

23

collected must be coded according to the proto-col)

● before analysis, a retrospective data validationperformed to identify missing values, inconsist-encies, outliers/possible errors, unexpected val-ues or codes.

3.4.1.3 Analysis

Information should be collected only if it will beused in the analysis.

Analysis includes the description of the population,frequency of risk exposure and infections, calcula-tion of rates, comparisons of patient groups (withsignificance testing), comparisons of rates over time,etc.

For adequate sample size, and monitoring long-termtrends, continuous surveillance or surveillanceundertaken at periodic intervals of sufficient lengthis recommended.

Inclusion of risk factors allows stratification of pa-tients by risk, and risk-adjusted rates for accuratecomparisons. A single overall nosocomial infectionrate is not useful for inter-hospital comparisons.Adjusted rates will enable the unit or the hospital tocompare its performance over time with its ownprevious results, and with other similar units/hos-pitals, or with populations of patients with similarrisk levels.

Computerization of data collection and analysisshould be considered, if possible, as it will ensurerapid feedback and better data quality. Low-costcomputers and different types of software are nowwidely available to facilitate analysis for the epide-miologist. Information already collected and acces-sible through the hospital computer system shouldbe used, wherever possible. Integration of nosoco-mial infection surveillance into routine data han-dling should be encouraged by defining specificrequirements for hospital information systems.

3.4.2 Feedback/dissemination

To be effective, feedback must be prompt, relevantto the target group, i.e. the people directly involvedin patient care, and with the potential for maximalinfluence on infection prevention (i.e. surgeons forsurgical site infection, physicians and nurses in in-tensive care units). Reporting may include meetingsfor sharing of information and discussion, micro-

biological review, and summary or graphic presen-tations on a notice board in the unit. Disseminationof information is also organized through the Infec-tion Control Committee to other units, management,and laboratories.

Reports should not identify individual patients.Codes must also be assigned to hospitals, units andresponsible physicians, to ensure anonymity. Reportsmust be returned or disposed of confidentially fol-lowing established procedures.

3.4.3 Prevention and evaluation

An effective surveillance system must identify pri-orities for preventive interventions and improvementin quality of care (18).

By providing quality indicators, surveillance enablesthe infection control programme, in collaborationwith patient care units, to improve practice, and todefine and monitor new prevention policies. Thefinal aim of surveillance is to decrease nosocomialinfections and reduce costs.

Surveillance is a continuous process which needs toevaluate the impact of interventions to validate theprevention strategy, and determine if initial objec-tives are attained.

3.5 Evaluation of the surveillance system

A surveillance system must be continuing if it is tobe credible. Periodic contacts with staff will also helpto maintain a high level of compliance. Once thesurveillance system is functioning, a validation ofthe surveillance methods and data should be un-dertaken at regular intervals, considering thefollowing criteria:

3.5.1 Evaluation of the surveillance strategy

Review whether the surveillance system meets therequired characteristics (19,20):

● simplicity/flexibility/acceptance

● timeliness (is the feedback prompt enough to beuseful?)

● utility (in terms of priorities, impact, etc.)

● efficacy/efficiency

Evaluation can be undertaken, for example, througha questionnaire study exploring how feedback is



24

perceived and how results are used by differentgroups.

3.5.2 Feedback evaluation

Specific issues which may be addressed are:

● Confidentiality: is it respected? Is it compatiblewith an optimum use of the results for preven-tion?

● Exchanges and publication: are the results dis-cussed adequately in the units and the hospital,are inter-facility results reviewed in the contextof the relevant literature?

● Comparability

— representativity: is the population under sur-veillance representative of the hospital, or ofthe specific patient group?

— risk adjustment/stratification: are these appro-priate?

— sample size: the length of the surveillance pe-riod may be adjusted to obtain a sufficientnumber of patients for valid analysis.

3.5.3 Validity/data quality

A data quality evaluation should be periodicallyundertaken, with criteria such as (19):

● For the denominator:

— exhaustiveness (missing patients)

TABLE 4. Data quality for the numerator

Condition PRESENT (patient infected)YES NO

Detected YES A (true positive) B (false positive)bysurveillance NO C (false negative) D (true negative)

Sensitivity= proportion of patients detected as being infected who

actually are infected (true positive) among infectedpatients = (A/A+C)

Specificity= proportion of patients detected as “non-infected” who

actually are non-infected (true negative) among non-infected patients = (D/B+D)

Predictive value positive= proportion of patients detected as being infected who

actually are infected (true positive) among “infectedpatients” detected by the surveillance = (A/A+B)

— completeness (missing data)

— correctness (wrong data).

● For the numerator: see Table 4.

Validation methods used will depend on timeliness,areas of surveillance, and resources (e.g. parallelprospective collection with a trained “expert” inves-tigator for a short period, retrospective validation ofa random sample of registered records by an inves-tigator considered as a “gold standard”).

The four principal points for nosocomial infec-tion surveillance:

● valid quality indicators (risk-adjusted rates, etc.)

● effective, timely feedback (rapid, useful)

● appropriate implementation of interventions

● evaluation of the impact of interventions by con-tinued surveillance (trends), and other studies

References

1. Gaynes RP. Surveillance of nosocomial infections.In: Hospital infections, fourth edition. Bennet andBrachman, eds. Philadelphia, Lippincott-Raven,1998:65–84.

2. Lee TB et al. Recommended practices for surveil-lance. Am J Infect Control, 1998, 26:277–288.

3. Pottinger JM, Herwaldt LA, Perl TM. Basics of sur-veillance — An overview. Infect Control HospEpidemiol, 1997, 18:513–527.

4. Thacker SB et al. A method for evaluation sys-tems of epidemiogical surveillance. Wld Hlth StatistQuart, 1988, 41:11–18.

5. NNIS report, Centers for Disease Control, Atlanta.Nosocomial infection rates for interhospital com-parison: limitations and possible solutions. InfectControl Hosp Epidemiol, 1991, 12:609–621.

6. Emory TG et al. National Nosocomial InfectionsSurveillance System. Description of surveillancemethods. Am J Infect Control, 1991, 19:19–35.

7. Roy MC. Basics of surgical site infection surveil-lance. Infect Control Hosp Epidemiol, 1997, 18:659–668.

25

8. Sherertz RJ et al. Consensus paper on the sur-veillance of surgical wound infections. Am J InfectControl, 1992, 20:263–270.

9. HELICS report. European recommendations fornosocomial infection surveillance in intensivecare units. Hygiènes, 1999, 7:127–134.

10. HELICS report. European recommendations forsurgical site infection surveillance. Hygiènes, 1999,7:51–59.

11. Freeman J. Modern quantitative epidemiology inthe hospital. In: Hospital epidemiology and infectioncontrol. Mayhall CG, ed. Baltimore, Williams &Wilkins, 1996.

12. National Nosocomial Infections Surveillance(NNIS) System Report, Data summary from Janu-ary 1990–May 1999. Issued June 1999. Am J InfectControl, 1999, 27:520–532.

13. Perl TM. Surveillance, reporting and the use ofcomputers. In: Prevention and control of nosocomialinfections, third edition. RP Wenzel, ed. Baltimore,Williams & Wilkins, 1997:127–161.

14. Emory TG, Gaynes RP. An overview of nosoco-mial infections including the role for the micro-biology laboratory. Clin Microbiol Rev, 1993,6:428–442.

15. Glenister H et al. An assessment of selective sur-veillance methods for detecting hospital-acquiredinfection. Am J Med, 1991, 91 (suppl. 3b):121S–124S.

16. Gardner JS et al. CDC definitions for nosocomialinfections, 1988. Am J Infect Control, 1988, 16:128–140.

17. Horan TC et al. CDC definitions of nosocomialsurgical site infections, 1992: a modification ofCDC definitions of surgical wound infections.Infect Control Hosp Epidemiol, 1992, 13:606–608.

18. Emmerson AM. The impact of surveys on hospi-tal infection. J Hosp Infect, 1995, 30:421–440.

19. Centers for Disease Control, Atlanta. Guidelinesfor evaluating surveillance systems. MMWR, 1988,37 (suppl. n° S5).

20. Dettenkofer M, Daschner FD. Cost-effectivenessof surveillance methods. Baillère’s clinical infectiousdiseases, July 1996, Vol 3, No. 2. Emmerson andAyliffe, eds. London, Baillère Tindall.



26

CHAPTER IV

Dealing with outbreaks

● Confirm whether there is an outbreak by review-ing preliminary information on the number ofpotential cases, available microbiology, severityof the problem, and demographic data ofperson(s), place and time.

4.2.2 Case definition

A case definition should be developed. It must in-clude a unit of time and place and specific biologi-cal and/or clinical criteria. The inclusion andexclusion criteria for cases must be precisely identi-fied. A gradient of definition (as definite, probableor possible case) is often helpful. The definitionshould also differentiate between infection or colo-nization. Specific criteria to identify the index casemay also be developed if relevant information isavailable.

Example of case definition: A definite case patientwill be defined as a patient hospitalized in the geriat-ric ward in January, with diarrhoea, cramps, vomitingand in whom routine culture of faeces identifies en-terotoxin-producing staphylococci.

The case definition can change with time as newinformation becomes available, or with additionaldiagnostic information.

A data collection form for case-finding should bedeveloped, and include:

● demographic characteristics (e.g. age, sex, causeof admission/leading diagnosis, date of admission,date of any surgery, prior antimicrobials)

● clinical data (e.g. onset of symptoms and signs,frequency and duration of clinical features asso-ciated with the outbreak, treatments, devices)

● any other potentially relevant data.

An outbreak is defined as an unusual or unex-pected increase of cases of a known nosoco-

mial infection or the emergence of cases of a newinfection. Outbreaks of nosocomial infection shouldbe identified and promptly investigated because oftheir importance in terms of morbidity, costs andinstitutional image. Outbreak investigation may alsolead to sustained improvement in patient care prac-tices.

4.1 Identifying an outbreak

Early identification of an outbreak is important tolimit transmission among patients by health careworkers or through contaminated materials. A po-tential problem may be initially identified by nurses,physicians, microbiologists, or any other health careworker, or through a nosocomial infection surveil-lance programme. Appropriate investigations arerequired to identify the source of the outbreak, andto implement control measures. The control meas-ures will vary depending on the agent and mode oftransmission, but may include isolation proceduresor improvements in patient care or environmentalcleaning.

4.2 Investigating an outbreak

Systematic planning and implementation of an out-break investigation is necessary.

4.2.1 Planning the investigation

● Notify the appropriate individuals and depart-ments in the institution of the problem; establishterms of reference for the investigation. This mustinclude development of an outbreak team andclear delineation of authority.

● Infection control staff must be part of the out-break team.

27

The form must be straightforward to use. It is com-pleted with information extracted from medicalcharts, microbiology reports, pharmacy reports andlog books of affected wards. The data collected mustalso be checked for validity.

The clinical diagnosis will usually be confirmedmicrobiologically. Optimal diagnostic specimens tobe obtained from cases should be described. It maybe appropriate to store selected biological materialsfor future analysis in anticipation that new diag-nostic methods may become available.

To verify the outbreak, the number of cases or iso-lates observed during the putative outbreak periodis compared with the number of cases (or isolates)reported during the previous period, or with thenumber of cases (or isolates) reported in the sameperiod of time one month or one year earlier.

4.2.3 Describing the outbreak

The detailed description includes person(s), place, andtime. Cases are also described by other characteris-tics such as gender, age, date of admission, transferfrom another unit, etc. The graphic representationof the distribution of cases by time of onset is anepidemic curve. The epidemic curve should distin-guish between definite and probable cases. The shape

CHAPTER IV. DEALING WITH OUTBREAKS

FIGURE 1. Epidemic curve in case of single pointsource outbreak*

1–2 5–6 7–8 9–10 11–12 13–14 15–160

2

4

6

8

10

12

14

16

Num

ber

of c

ases

Days

3–4

* Adapted from Astagneau P. Duneton P. Management of epidemics ofnosocomial infections. Pathol Biol (Paris) 1998, 46:272–278.

* Adapted from Astagneau P. Duneton P. Management of epidemics ofnosocomial infections. Pathol Biol (Paris) 1998, 46:272–278.

FIGURE 2. Epidemic curve in case of ongoingtransmission*

Jan Feb Mar Apr May Jun Jul

Months

0

2

4

3

5

6

7

8

9

Num

ber

of c

ases

1

of the epidemic curve may suggest a single pointsource (Figure 1), ongoing transmission (Figure 2), oran intermittent source (Figure 3).

These data allow the calculation of an attack rate,defined by:

Number of people at risk who are infected

Total number of people at risk

The attack rate can also be calculated stratified byrelevant characteristics such as sex, age, location, orspecific exposure (ventilation, catheterization, oper-ating rooms, occupational exposure).

At the end of the descriptive analysis, it should bepossible to:

● formulate a hypothesis on the type of infection(exogenous, endogenous)

● tentatively identify the source and route of infec-tion

● suggest and implement initial control measures.

4.2.4 Suggesting and testing a hypothesis

This includes identifying a potential exposure (typeand route) for the outbreak and testing this hypoth-esis using statistical methods. A review of the cur-


28

rent literature may help identify possible routes ofinfection for the suspected or known infecting agents.

A case-control study is the most common approachto hypothesis testing. This compares the frequencyof a risk factor in a group of cases (i.e. individualswith the nosocomial infection) and in a group ofcontrols (i.e. individuals without the infection). Con-trols must be carefully selected to limit bias. Two ormore controls for each case may be necessary toprovide sufficient statistical power. By definition, thecontrols are not-cases (individuals without the no-socomial infection or colonization). Further in-depthdiscussion of the selection of controls is describedin several other sources (1,2,3).

The strength of association between exposure anddisease is quantified by the odds ratio in case-control studies (or the relative risk for cohort stud-ies), with a 95% confidence interval. The role ofchance, confounding, and bias should be consideredin interpreting results.

TABLE 1. Immediate control measures for outbreak management

Type of transmission suspected Suggested action

Cross-transmission (transmission between Patient isolation and barrier precautions determined byindividuals) infectious agent(s)

Hand transmission Improvements in handwashing; cohorting

Airborne agent Patient isolation with appropriate ventilation

Agent present in water, waterborne agent Checking of water supply and all liquid containersUse of disposable devices

Foodborne agent Elimination of the food at risk

4.2.5 Control measures and follow-up

The aims are:

● to control the current outbreak by interruptingthe chain of transmission

● to prevent future occurrence of similar outbreaks.

The selection of control measures (Table 1) is deter-mined by results of the initial analysis in consulta-tion with appropriate professionals (infection controlstaff, epidemiologist, clinicians, microbiologists, nurs-ing). This is also an opportunity to initiate or im-prove a surveillance system to facilitate evaluationof the efficacy of the control procedures instituted.Continuous surveillance may be implemented inhigh-risk units (see Chapter III).

4.2.6 Communication

During the investigation of an outbreak, timely, up-to-date information must be communicated to the

1–2

Weeks (i.e. 1–2 : 3 cases between the 1st and the 2nd week)

0

2

4

3

5

6

Num

ber

of c

ases

1

2–3

3–4

4–5

5–6

6–7

7–8

8–9

9–10

10–1

1

11–1

2

12–1

3

13–1

4

14–1

5

15–1

6

16–1

7

17–1

8

18–1

9

19–2

0

20–2

1

21–2

2

22–2

3

23–2

4

24–2

5

FIGURE 3. Epidemic curve in case of intermittent source*

* adapted from Astagneau P, Duneton P.Management of epidemics of nosocomial infections. Pathol Biol (Paris) 1998, 46:272–278.

29

hospital administration, public health authorities,and, in some cases, to the public. Information maybe provided to the public and to the media withagreement of the outbreak team, administration andlocal authorities.

A final report on the outbreak investigation shouldbe prepared. It should describe the outbreak, inter-ventions, and effectiveness, and summarize the con-tribution of each team member participating in theinvestigation. It should also make recommendationsto prevent future occurrence. This report can bepublished in the medical literature, and may be con-sidered as a legal document.

References

1. Gordis L. Epidemiology. Philadelphia, W.B. SaundersCompany, 1996.

2. Fletcher RH et al. Clinical epidemiology, the essentials.Baltimore, Williams & Wilkins, 1996.

3. Hennekens CH, Buring JE. Epidemiology in medicine.Mayrent SL, ed. Boston/Toronto, Little, Brown andCompany, 1987.

CHAPTER IV. DEALING WITH OUTBREAKS


30

CHAPTER V

Prevention of nosocomial infection

Prevention of nosocomial infections requires anintegrated, monitored, programme which in-

cludes the following key components:

● limiting transmission of organisms between pa-tients in direct patient care through adequatehandwashing and glove use, and appropriateaseptic practice , isolation strategies, sterilizationand disinfection practices, and laundry

● controlling environmental risks for infection

● protecting patients with appropriate use of pro-phylactic antimicrobials, nutrition, and vaccina-tions

● limiting the risk of endogenous infections by mini-mizing invasive procedures , and promoting op-timal antimicrobial use

● surveillance of infections, identifying and control-ling outbreaks

● prevention of infection in staff members

● enhancing staff patient care practices, and con-tinuing staff education.

Infection control is the responsibility of all healthcare professionals — doctors, nurses, therapists, phar-macists, engineers and others.

TABLE 1. Differential nosocomial infection risk by patient and interventions

Risk of infection Type of patients Type of procedures

1 Not immunocompromised; no significant Non-invasiveMinimal underlying disease No exposure to biological fluids *

2 Infected patients, or patients with some Exposure to biological fluidsMedium risk factors (age, neoplasm) or

Invasive non-surgical procedure (e.g. peripheralvenous catheter, introduction of urinary catheter)

3 Severely immunocompromised patients, SurgeryHigh (<500 WBC per ml); multiple trauma, or

severe burns, organ transplant High-risk invasive procedures (e.g. central venouscatheter, endotracheal intubation)

* Biological fluids include blood, urine, faeces, CSF, fluid from body cavities.

5.1 Risk stratification (1)

Acquisition of nosocomial infection is determinedby both patient factors, such as degree of immuno-compromise, and interventions performed whichincrease risk. The level of patient care practice maydiffer for patient groups at different risk of acquistionof infection. A risk assessment will be helpful tocategorize patients and plan infection control inter-ventions.

Tables 1 and 2 provide an example of an approachwhich could be customized to a particular facility.Table 1 stratifies the risk for different patient groups,and Table 2 provides a hierarchy of patient care prac-tice for different levels of patient risk.

5.2 Reducing person-to-person transmission

5.2.1 Hand decontamination

The importance of hands in the transmission of hos-pital infections has been well demonstrated (2), andcan be minimized with appropriate hand hygiene(3,4,5). Compliance with handwashing, however, isfrequently suboptimal. This is due to a variety ofreasons, including: lack of appropriate accessibleequipment, high staff-to-patient ratios, allergies to

31

handwashing products, insufficient knowledge ofstaff about risks and procedures, too long a dura-tion recommended for washing, and the timerequired.

5.2.1.1 Optimal “hand hygiene” requirements

For handwashing:

● running water: large washbasins which requirelittle maintenance, with antisplash devices andhands-free controls

● products: soap or antiseptic depending on theprocedure

● facilities for drying without contamination (dis-posable towels if possible).

For hand disinfection:

● specific hand disinfectants: alcoholic rubs withantiseptic and emollient gels which can be ap-plied to physically clean hands.

5.2.1.2 Procedures

There must be written policies and procedures forhandwashing. Jewellery must be removed beforewashing. Simple hygiene procedures may be lim-ited to hands and wrists; surgical procedures includethe hand and forearm.

Procedures will vary with the patient risk assess-ment (Table 3):

CHAPTER V. PREVENTION OF NOSOCOMIAL INFECTION

TABLE 2. Aseptic measures appropriate for different levels of risk of infection

Risk of infection Asepsis Antiseptics Hands Clothes Devices*

1 Clean None Simple Street clothes Clean orMinimal handwashing or disinfected at

hand disinfection intermediate orby rubbing low level

2 Asepsis Standard Hygienic Protection Disinfected atMedium antiseptic handwashing or against blood sterile or high

products hand disinfection and biological levelby rubbing fluids, as

appropriate

3 Surgical Specific major Surgical Surgical clothes: Disinfected atHigh asepsis products handwashing or dress, mask, caps, sterile or high

surgical hand sterile gloves leveldisinfection byrubbing

* All devices entering sterile body cavities must be sterile.

● routine care (minimal):

— handwashing with non-antiseptic soap

— or quick hygienic hand disinfection (by rub-bing) with alcoholic solution

● antiseptic handcleaning (moderate) — asepticcare of infected patients:

— hygienic handwashing with antiseptic soapfollowing manufacturers instructions (e.g. oneminute)

— or quick hygienic hand disinfection: as previ-ously

● surgical scrub (surgical care):

— surgical hand and forearm washing withantiseptic soap and sufficient time and dura-tion of contact (3–5 minutes)

— or surgical hand and forearm disinfection: sim-ple handwash and drying followed by twoapplications of hand disinfectant, then rub todry for the duration of contact defined by theproduct.

5.2.1.3 Resource availability

Equipment and products are not equally accessiblein all countries or health care facilities. Flexibility inproducts and procedures, and sensitivity to localneeds, will improve compliance. Table 3 providessuggestions to adapt handwashing for different avail-ability of resources. In all cases, the maximum pro-cedure possible should be instituted.


32

5.2.2 Personal hygiene

All staff must maintain good personal hygiene. Nailsmust be clean and kept short. False nails should notbe worn. Hair must be worn short or pinned up.Beard and moustaches must be kept trimmed shortand clean.

5.2.3 Clothing

Working clothes

Staff can normally wear a personal uniform or streetclothes covered by a white coat. In special areas suchas burn or intensive care units, uniform trousers anda short-sleeved gown are required for men and

TABLE 3. Hand care and economic constraints

Level Good resources Limited resources Very limited resources

1 Simple handwashing: Simple handwashing: Simple handwashing:Routine Equipment: large wash-basin, Equipment: large wash-basin, Equipment: clean water, locally(minimal) water and automatically water and locally made soap made soap (dry), towels

distributed washing agent, (dry), individual towels washed dailyliquid soap, disposable towels

Hygienic hand disinfection by Hygienic hand disinfection byHygienic hand disinfection by rubbing: rubbing:rubbing: Specified duration of contact Specified duration of contactSpecified duration of contact with hand disinfectant or with alcohol and rub to drybetween hand and disinfectant, alcohol, rub to dryrub to dry

2 Hygienic (or antiseptic) Hygienic (or antiseptic) Simple handwashing:Antiseptic handwashing: handwashing: Equipment: clean water, locallyhand cleaning Equipment: large wash-basin, Equipment: large wash-basin, made soap (dry), towels washed

water and automatically water and locally made soap dailydistributed washing agent, (dry) if antisepsis is undertakenantiseptic scrub (one-minute after the washing. Hygienic hand disinfectioncontact), disposable towels Otherwise: antiseptic scrub by rubbing:

(1 minute contact), individual Associated with alcoholHygienic hand disinfection towels antisepsis, contact and rub to dryby rubbing:Specified duration of hand- Hygienic hand disinfectiondisinfectant contact, rub to dry by rubbing:

Specified duration of contactwith disinfectant or alcohol,rub to dry

3 Surgical hand-forearm-washing: Simple hand-forearm-washing: Simple hand-forearm-washing:Surgical scrub Equipment: large wash-basin, Equipment: large wash-basin, Equipment: clean water, locally(maximal) water and automatically water and locally made soap made soap (dry), towels washed

distributed washing agent, (dry), individual towels dailygood antiseptic scrub (contact3 to 5 minutes), sterile Hygienic hand disinfection Hygienic hand disinfectiondisposable towels by rubbing: by rubbing:

Associated with antisepsis: Associated with alcoholSurgical hand disinfection specific hand disinfectant, antisepsis, repeated twiceby rubbing: repeated twiceEquipment as for level 2: goodsoft soap, specific handdisinfectant, repeated twice.

women. In other units, women may wear a short-sleeved dress.

The working outfit must be made of a material easyto wash and decontaminate. If possible, a clean out-fit should be worn each day. An outfit must bechanged after exposure to blood or if it becomeswet through excessive sweating or other fluid expo-sure.

Shoes

In aseptic units and in operating rooms, staff mustwear dedicated shoes, which must be easy toclean.

33

Caps

In aseptic units, operating rooms, or performingselected invasive procedures, staff must wear capsor hoods which completely cover the hair.

5.2.4 Masks (6)

Masks of cotton wool, gauze, or paper are ineffec-tive. Paper masks with synthetic material for filtra-tion are an effective barrier against microorganisms.

● Masks are used in various situations; mask re-quirements differ for different purposes.

● Patient protection: staff wear masks to work inthe operating room, to care for immuno-compro-mised patients, to puncture body cavities. A sur-gical mask is sufficient.

● Staff protection: staff must wear masks when car-ing for patients with airborne infections, or whenperforming bronchoscopies or similar examina-tion. A high-efficiency mask is recommended.

● Patients with infections which may be transmit-ted by the airborne route must use surgical maskswhen outside their isolation room.

5.2.5 Gloves (6)

Gloves are used for:

● Patient protection: staff wear sterile gloves forsurgery, care for immunocompromised patients,invasive procedures which enter body cavities.

● Non-sterile gloves should be worn for all patientcontacts where hands are likely to be contami-nated, or for any mucous membrane contact.

● Staff protection: staff wear non-sterile gloves tocare for patients with communicable disease trans-mitted by contact, to perform bronchoscopies orsimilar examinations.

● Hands must be washed when gloves are removedor changed.

● Disposable gloves should not be reused.

● Latex or polyvinyl-chloride are the materials mostfrequently used for gloves. Quality, i.e. absence ofporosity or holes and duration of use vary con-siderably from one glove type to another. Sensi-tivity to latex may occur, and the occupationalhealth programme must have policies to evalu-ate and manage this problem.


5.2.6 Safe injection practices

To prevent transmission of infections betweenpatients with injections:

● eliminate unnecessary injections

● use sterile needle and syringe

● use disposable needle and syringes, if possible

● prevent contamination of medications

● follow safe sharps disposal practices (Chapter VII,8.5).

For more information, refer to the WHO guide “Bestinfection control practices for skin-piercing intra-dermal, subcutaneous, and intramuscular needleinjections” (7).

5.3 Preventing transmission from theenvironment

To minimize the transmission of microorganismsfrom equipment and the environment, adequatemethods for cleaning, disinfecting and sterilizingmust be in place. Written policies and procedureswhich are updated on a regular basis must be de-veloped for each facility.

5.3.1 Cleaning of the hospital environment(5,6,8)

● Routine cleaning is necessary to ensure a hospi-tal environment which is visibly clean, and freefrom dust and soil.

● Ninety per cent of microorganisms are presentwithin “visible dirt”, and the purpose of routinecleaning is to eliminate this dirt. Neither soap nordetergents have antimicrobial activity, and thecleaning process depends essentially on mechani-cal action.

● There must be policies specifying the frequencyof cleaning and cleaning agents used for walls,floors, windows, beds, curtains, screens, fixtures,furniture, baths and toilets, and all reused medi-cal devices.

● Methods must be appropriate for the likelihoodof contamination, and necessary level of asepsis.This may be achieved by classifying areas intoone of four hospital zones (8):

— Zone A: no patient contact. Normal domesticcleaning (e.g. administration, library).


34

— Zone B: care of patients who are not infected,and not highly susceptible, cleaned by a pro-cedure that does not raise dust. Dry sweepingor vacuum cleaners are not recommended. Theuse of a detergent solution improves the qual-ity of cleaning. Disinfect any areas withvisible contamination with blood or bodyfluids prior to cleaning.

— Zone C: infected patients (isolation wards).Clean with a detergent/disinfectant solution,with separate cleaning equipment for eachroom.

— Zone D: highly-susceptible patients (protectiveisolation) or protected areas such as operatingsuites, delivery rooms, intensive care units,premature baby units, casualty departmentsand haemodialysis units. Clean using a deter-gent/disinfectant solution and separate clean-ing equipment.

All horizontal surfaces in zones B, C and D, and alltoilet areas should be cleaned daily.

● Bacteriological testing of the environment is notrecommended except in selected circumstancessuch as:

— epidemic investigation where there is a sus-pected environmental source

— dialysis water monitoring for bacterial counts,as required by standards (see Chapter VIII)

— quality control when changing cleaning prac-tices.

5.3.2 Use of hot/superheated water

An alternative to disinfection for environmentalcleaning for some objects is hot water (Table 4).

TABLE 4. Disinfection with hot water

Temperature Duration

1. Sanitary 80 °C 45–60 secondsequipment

2. Cooking 80 °C 1 minuteutensils

3. Linen 70 °C 25 minutes95 °C 10 minutes

5.3.3 Disinfection of patient equipment

Disinfection removes microorganisms without com-plete sterilization to prevent transmission of organ-isms between patients. Disinfection procedures must(5,9,10):

● meet criteria for killing of organisms

● have a detergent effect

● act independently of the number of bacteriapresent, the degree of hardness of the water, orthe presence of soap and proteins (that inhibitsome disinfectants).

To be acceptable in the hospital environment, theymust also be:

● easy to use

● non-volatile

● not harmful to equipment, staff or patients

● free from unpleasant smells

● effective within a relatively short time.

For further recommendations, see Tables 5 and 6. Inusing a disinfectant, manufacturers recommenda-tions must always be followed. Different productsor processes achieve different levels of disinfection.These are classified as high-, intermediate- orlow-level disinfection (11); Table 5 provides charac-teristics of the three levels, and Table 6 makesrecommendations for the level of disinfection for dif-ferent patient care activity.

High-level disinfection (critical) — this will destroyall microorganisms, with the exception of heavy con-tamination by bacterial spores.

Intermediate disinfection (semi-critical) — thisinactivates Mycobacterium tuberculosis, vegetativebacteria, most viruses and most fungi, but does notnecessarily kill bacterial spores.

Low-level disinfection (non-critical) — this can killmost bacteria, some viruses and some fungi, but can-not be relied on for killing more resistant bacteriasuch as M. tuberculosis or bacterial spores.

These levels of disinfection are attained by using theappropriate chemical product in the manner appro-priate for the desired level of disinfection.

5.3.4 Sterilization (5–13)

Sterilization is the destruction of all microorganisms.Operationally this is defined as a decrease in the

35


TABLE 5. Spectrum of activity achieved of the main disinfectants

Level of Spectrum of Active ingredients potentially Factors affectingdisinfection activity of capable of satisfying these the efficacy ofrequired desinfectant spectra of activity a disinfectant

High • Sporicidal • Peracetic acid • Concentration• Mycobactericidal • Chlorine dioxide • Contact time• Virucidal • Formaldehyde • Temperature• Fungicidal • Glutaraldehyde • Presence of organic matter• Bactericidal • Sodium hypochlorite • pH

• Stabilized hydrogen peroxide • Presence of calcium or magnesium• Succinaldehyde (succinic aldehyde) ions (for example, hardness of the

water used for dilution)Intermediate • Tuberculocidal • Phenol derivatives • Formulation of the disinfectant

• Virucidal • Ethyl and isopropyl alcohols used• Fungicidal• Bactericidal

Low • Bactericidal • Quaternary ammonium• Amphiprotic• Amino acids

TABLE 6. Level of disinfection for patient equipment in relation with type of care (11,12)

Devices use Class Level of risk Level of disinfection

Into vascular system, into sterile cavity, • critical • high • sterilization orinto sterile tissues: high-level disinfectionSurgical instrumentation, e.g. athro-scopes, biopsies, instrumentation, etc.

Mucous membrane contact, • semi-critical • medium • disinfection of mediannon-intact skin: levele.g. gastroscopy, etc.

Intact skin or without contact • non-critical • low • disinfection of low levelwith patient:e.g. beds, sink, etc.

microbial load by 10-6. Sterilization can be achievedby either physical or chemical means (Table 7).

● Sterilization is required for medical devices pen-etrating sterile body sites, as well as all parenteralfluids and medications.

● For reprocessed equipment, sterilization must bepreceded by cleaning to remove visible soil.

● The object must be wrapped for sterilization. Onlya wrapped sterilized object should be describedas sterile:

Materials for packaging include:

— paper which prevents contamination if intact,maintains sterility for a long period, can actas a sterile field, and can also be used to wrapdirty devices after the procedure

TABLE 7. Principal sterilization methods

Thermal sterilization

• Wet sterilization: exposure to steam saturated withwater at 121 °C for 30 minutes, or 134 °C for 13minutes in an autoclave; (134 °C for 18 minutes forprions).

• Dry sterilization: exposure to 160 °C for 120 minutes,or 170 °C for 60 minutes; this sterilization process isoften considered less reliable than the wet process,particularly for hollow medical devices.

Chemical sterilization

• Ethylene oxide and formaldehyde for sterilization arebeing phased out in many countries because of safetyand greenhouse gas emission concerns.

• Peracetic acid is widely used in the United States andsome other countries in automatic processingsystems.


36

— selected plastics; only polyethylene and poly-propylene are suitable for sterilization withethylene oxide

— non-woven disposable textiles

— containers can be used only if they containmaterial intended for a single treatment pro-cedure for a single patient. They must be pro-vided with a filter and a valve, which must bemonitored regularly.

● Packaging systems for sterile items shall meetlocal legislation and/or regulations, but mustnevertheless:

— provide adequate seal integrity and be tamper-proof

— provide an adequate barrier to particulatematter

— withstand physical conditions of the steriliza-tion process

— provide an adequate barrier to fluids

— permit adequate air removal

— allow penetration and removal of sterilant

— protect package content from physical dam-age

— resist tears and punctures

— be free of holes

— be free of toxic ingredients

— have a low lint content

— have a positive cost/benefit ratio

— be used according to the manufacturers’ writ-ten instructions

— be dated.

● Proper storage conditions are essential to main-tain the integrity of sterilized items.

● The end-user must check the integrity of the pack-age before use.

● The sterilization of endoscopes, minimally inva-sive instruments, and robotic instrumentation isnecessary, but may present a particular challengebecause of the configuration of these instruments.

● Quality control parameters for the sterilizationprocess must record information on the steriliza-tion processing cycle including:

— load number

— load content

— temperature and time exposure record chart

— regular (at least daily) physical/chemical test-ing

— regular (at least weekly) biological testing

— steam processing (Bacillus stearothermophilus)

— ethylene oxide processing (Bacillus subtilis v.niger).

● Regular maintenance must be performed anddocumented. The following records must be main-tained for all sterilization:

— date of service

— model and serial number

— location

— descriptions of replaced parts

— biological testing records

— Bowie-Dick test

— name and signature of controller.

Endoscope reprocessing

Endoscopes are medical devices which may be prob-lematic to clean and disinfect (long narrow channels,complex internal design, etc.). Products and/or proc-esses used (chemical or thermo-chemical disinfection)may not be as reliable as sterilization methods.

To reduce nosocomial transmission of microorgan-isms by endoscopy a standard reprocessing proce-dure must be systematically followed.

1. Immediately after use, the air-water channel shouldbe cleared with forced air, and tap water or deter-gent suctioned or pumped through the aspiration/biopsy channel(s) to remove organic debris.

2. All detachable parts (e.g. hoods and suction valves)should be removed and soaked in a detergent so-lution, and the external parts of the endoscopesgently wiped.

3. All accessible channels should then be irrigatedwith tap water or detergent solution, brushed (us-ing sterile or single use brush) and purged.

4. Before any immersion, the endoscope must beleak-tested.

37

Endoscope reprocessing continued

After pre-treatment and mechanical cleaning the en-doscope should be cleaned and disinfected, eithermanually or automatically. In both cases, the completecycle includes several stages:

5. Cleaning using an approved detergent (this solu-tion cannot be reused).

6. Rinsing (tap water is sufficient for this in-betweenrinsing stage).

7. Disinfection. Using an approved, high level disin-fectant.

Regarding CJD risk, a disinfectant with protein-fixative properties (i.e. aldehyde-based products)should not be used. A non-fixative desinfectantshould be selected.

8. Rinsing: The level of microbial purity of the waterused depends on the further use of the endoscope(bacteriologically controlled water or sterilewater).

9. Drying: If the endoscope is not stored, this dryingstage includes only air-blowing the channel to re-move residual water.

Note: new French guidelines regarding variantCreutzfeldt-Jakob (CJD) risk recommend to clean andrinse the endoscope twice before disinfection.

References

1. Underwood MA, Pirwitz S. APIC guidelines com-mittee: using science to guide practice. Am J InfectControl, 1998, 26:141–144.

2. Larson E. A causelink between handwashing andrisk of infection? Examination of the evidence.Infect Control Hosp Epidemiol, 1988, 9:28–36.

3. CDC guidelines for handwashing and hospitalenvironmental control. Amer J Infect Control, 1986,14:110–129 or Infect Control, 1986, 7:231–242.

4. Larson EL. APIC guideline for handwashing andhand antisepsis in health care settings. Amer J In-fect Control, 1995, 23:251–269.

5. Health Canada. Hand washing, cleaning, disin-fection, and sterilization in health care. CanadaCommunicable Disease Report (CCDR), Supplement,Vol., 24S4, July 1998.

6. Pratt RJ et al. The epic project: Developing na-tional evidence-based guidelines for preventinghealthcare associated infections. Phase I: Guide-lines for preventing hospital-acquired infections.J Hosp Infect, 2001, 47(Supplement):S3–S4.

7. World Health Organization. Best infection controlpractices for skin-piercing intradermal, subcutaneous, andintramuscular needle injections. 2001, WHO/BCT/DCT/01.02.

8. Ducel G et al. Practical guide to the prevention of hospi-tal-acquired infections. 1979, WHO/BAC/79.1.

9. Association of Operating Room Nurses. Proposedrecommended practices for chemical disinfection.AORN J, 1994, 60: 463–466.

10. Rutala WA. APIC guideline for selection and useof disinfectants. Amer J Infect Control, 1996, 24:313–342.

11. Alvarado CJ, Reichelderfer M and the 1997, 1998,1999 APIC Guidelines Committees. APIC guide-line for infection prevention and control in flex-ible endoscopy. Amer J Infect Control , 2000,26:138–155.

12. Galtier F. La stérilisation hospitalière, 2ème édition.Paris, Maloine, 1998.

13. Medical Devices Agency. Department of Health (UK)sterilization, disinfection, and cleaning of medical equip-ment: Guidance on decontamination. London, Depart-ment of Health, 1996.



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CHAPTER VI

Prevention of common endemicnosocomial infections

6.1 Urinary tract infections (UTI)

Urinary tract infections are the most frequent noso-comial infections (1); 80% of these infections areassociated with an indwelling urethral catheter(Figure 1). Interventions effective in preventing no-socomial urinary infection include (2,3,4):

● avoiding urethral catheterization unless there isa compelling indication

The four most common nosocomial infections areurinary tract infections, surgical wound infec-

tions, pneumonia, and primary bloodstreaminfection. Each of these is associated with an inva-sive medical device or invasive procedure. Specificpolicies and practices to minimize these infectionsmust be established, reviewed and updated regu-larly, and compliance monitored (Table 1).

TABLE 1. Measures for prevention of infection

Infection Proven effective Proven not effective

Urinary tract Limit duration of catheter Systemic antibiotic prophylaxisinfections Aseptic technique at insertion Bladder irrigation or instillation of normal saline

Maintain closed drainage antiseptic or antibioticAntiseptic added to drainage bagAntimicrobial-coated catheterDaily antiseptic perineal cleaning

Surgical site Surgical technique Fumigationinfections Clean operating environment Preoperative shaving

Staff attireLimiting preoperative hospital stayPreoperative shower and local skin

preparation of patientOptimal antibiotic prophylaxisAseptic practice in operating roomSurgical wound surveillance

Pneumonia Ventilator-associated Digestive decontamination for all patientsAseptic intubation and suctioning Changes of ventilator circuit every 48 orLimit duration 72 hoursNon-invasive ventilation

OthersInfluenza vaccination for staffIsolation policySterile water for oxygen and aerosol therapyPrevention of Legionella and Aspergillus

during renovations

Vascular device All catheters Antimicrobial creams for skin preparationinfections Closed system

Limit durationLocal skin preparationAseptic technique at insertionRemoval if infection suspected

Central linesSurgical asepsis for insertionLimitation of frequency of dressing changeAntibiotic-coated catheter for short term

39

● limiting the duration of drainage, if catheteriza-tion is necessary

● maintaining appropriate aseptic practice duringurinary catheter insertion and other invasiveurological procedures (e.g. cystoscopy, urodynamictesting, cystography)

● hygienic handwash or rub prior to insertion andfollowing catheter or drainage bag manipulation(Chapter V)

● sterile gloves for insertion

● perineal cleaning with an antiseptic solution priorto insertion

● non-traumatic urethral insertion using an appro-priate lubricant

● maintaining a closed drainage system.

Other practices which are recommended, but notproven to decrease infection include:

● maintaining good patient hydration

● appropriate perineal hygiene for patients withcatheters

● appropriate staff training in catheter insertion andcare

● maintaining unobstructed drainage of the blad-der to the collection bag, with the bag below thelevel of the bladder.

Generally, the smallest diameter catheter should beused. Catheter material (latex, silicone) does not in-fluence infection rates.

For patients with a neurogenic bladder:

● avoid an indwelling catheter if possible

● if assisted bladder drainage is necessary, cleanintermittent urinary catheterization should beused.

6.2 Surgical wound infections (surgical siteinfections)

Factors which influence the frequency of surgicalwound infection include (5,6,7,8):

● surgical technique

● extent of endogenous contamination of thewound at surgery (e.g. clean, clean-contaminated)

● duration of operation

● underlying patient status

● operating room environment

● organisms shed by the operating room team.

A systematic programme for prevention of surgicalwound infections (5) includes the practice of opti-mal surgical technique, a clean operating room en-vironment with restricted staff entry and appropriate

CHAPTER VI. PREVENTION OF COMMON ENDEMIC NOSOCOMIAL INFECTIONS

Reproduced by permission of Wiley&Sons, Inc. from HospitalInfection Control: Principles and Practice, M. Castle, Copyright © 1980by John Wiley & Sons, Inc.

FIGURE 1. Portals of entry for microorganisms in urinary drainage systems: the urethral meatus-catheterjunction; the catheter-drainage tubing junction; the drainage tubing-bag junction; andthe outlet that drains urine from the bag

Urethral meatus–catheter junction

Catheter–drainagetubing junction

Drainage–tubingbag junction

Outlet


40

staff attire, sterile equipment, adequate preoperativepreparation of the patient, appropriate use ofpreoperative antimicrobial prophylaxis, and a sur-gical wound surveillance programme. Surgicalwound infection rates are decreased by standard-ized surveillance for infection with reporting of ratesback to individual surgeons.

6.2.1 Operating room environment

Airborne bacteria must be minimized, and surfaceskept clean. A recommended schedule for cleaningand disinfection of the operating theatre is:

● every morning before any intervention: cleaning of allhorizontal surfaces

● between procedures: cleaning and disinfection of hori-zontal surfaces and all surgical items (e.g.tables, buckets)

● at the end of the working day: complete cleaning ofthe operating theatre using a recommended dis-infectant cleaner

● once a week: complete cleaning of the operatingroom area, including all annexes such as dress-ing rooms, technical rooms, cupboards.

All items used within a sterile field must be sterile.Sterile drapes must be placed on the patient and onany equipment included in the sterile field; thesedrapes must be handled as little as possible. Once asterile drape is in position, it must not be moved;shifting or moving the sterile drape compromisesthe sterile field.

For selected high-risk surgery (e.g. orthopaedic pro-cedures with implants, transplantation) furtherspecific measures for operating room ventilation maybe considered (Chapter VIII).

6.2.2 Operating room staff

6.2.2.1 Handwashing

A surgical hand disinfection should be performedby all persons participating in the operative proce-dure (Chapter V).

6.2.2.2 Operating room attire

Operating staff must wear sterile gloves. The reportedoccurrence of glove punctures ranges from 11.5% to53% of procedures (9), and double gloving is there-fore advisable for procedures with a high risk of

puncture, such as total joint arthroplasty. Doublegloving is also recommended when operating onpatients known to be infected with bloodbornepathogens such as the human immunodeficiencyvirus (HIV), hepatitis B, or hepatitis C (10). Glovesshould be changed immediately after any acciden-tal puncture.

All persons entering the surgical theatre must wearsurgical attire restricted to being worn only withinthe surgical area. The design and composition ofsurgical attire should minimize bacterial sheddinginto the environment.

All head and facial hair, including sideburns, andneckline, must be covered. All personnel entering inthe operating suite must remove any jewellery; nailpolish or artificial nails must not be worn.

Full coverage of the mouth and nose area with asurgical mask for everyone entering the operatingsuite (11).

Sterile surgical gowns must be worn by all personsparticipating directly in the operation. Waterproofgowns or aprons should be worn for procedures athigh risk of blood contamination.

6.2.2.3 Operating room activitiy

● The number of persons entering the theatre dur-ing an operation should be minimized.

● Unnecessary movement or conversation shouldbe avoided.

6.2.3 Pre-intervention preparation of thepatient

For elective procedures, any existing infectionsshould be identified and treated before surgery. Thepreoperative stay should be minimized. Any mal-nourished patient should have nutrition improvedbefore elective surgery.

The patient should normally be bathed or showeredon the evening before the intervention, using anantimicrobial soap. If hair removal is required, thisshould be done by clipping or with a depilatoryrather than by shaving (5,12).

The operative site must be washed with soap andwater, then an antimicrobial preoperative skin prepa-ration applied from the centre to the periphery.The area prepared must be large enough to includethe entire incision and adjacent skin sufficient for

41

the surgeon to work without contacting unpreparedskin.

The patient must be covered with sterile drapes; nopart is uncovered except the operating field andareas needed for the administration and maintenanceof anaesthesia.

6.2.4 Antimicrobial prophylaxis (see Chapter IX)

6.2.5 Surgical wound surveillance (see alsoChapter III)

● Prospective surgical wound surveillance shouldbe undertaken for selected procedures.

● Infection rates should be stratified by the extentof endogenous bacterial contamination at surgery:clean, clean-contaminated, or dirty.

● Surgical wound infection rates may also be strati-fied by duration of operation and underlyingpatient status.

● Individual surgeons should be provided their ownsurgical wound infection rates in a confidentialmanner, with a comparator of overall rates forthe facility or region.

6.3 Nosocomial respiratory infections (13)

Nosocomial respiratory tract infections occur in dif-ferent patient groups (10). In some cases, the hospi-tal environment may play a significant role (seeChapter VIII). Recommendations to prevent theseinfections include:

6.3.1 Ventilator-associated pneumonia in theintensive care unit

● Appropriate disinfection and in-use care of tub-ing, respirators, and humidifiers to limit contami-nation.

● No routine changes of respirator tubing.

● Avoid antacids and H2 blockers.

● Sterile tracheal suctioning.

● Nurse in head-up position.

6.3.2 Medical units

● Limit medications which impair consciousness(sedatives, narcotics).

● Position comatose patients to limit the potentialfor aspiration.

● Avoid oral feeds in patients with swallowing ab-normalities.

● Prevent exposure of neutropenic or transplantpatients to fungal spores during construction orrenovation (Chapter VIII).

6.3.3 Surgical units

● All invasive devices used during anaesthesia mustbe sterile.

● Anaesthetists must use gloves and mask whenundertaking invasive tracheal or venous or epi-dural care. Disposable filters (for individual use)for endotracheal intubation effectively prevent thetransmission of microorganisms among patientsby ventilators.

● Preoperative physiotherapy prevents postopera-tive pneumonia in patients with chronic respira-tory disease.

6.3.4 Neurological patients with tracheostomy(with or without ventilation)

● Sterile suctioning at appropriate frequency.

● Appropriate cleaning and disinfection of respira-tory machines and other devices.

● Physiotherapy to assist with drainage of secre-tions.

6.4 Infections associated with intravascularlines (3,14–16)

Local (exit site, tunnel) and systemic infections mayoccur (Figure 2). They are most common in inten-sive care units (14). Key practices for all vascular cath-eters include:

● avoiding catheterization unless there is a medicalindication

● maintaining a high level of asepsis for catheterinsertion and care

● limiting the use of catheters to as short a dura-tion as possible

● preparing fluids aseptically and immediatelybefore use

● training of personnel in catheter insertion andcare.



42

6.4.1 Peripheral vascular catheters

● Hands must be washed before all catheter care,using hygienic handwash or rub (Chapter V).

● Wash and disinfect skin at the insertion site withan antiseptic solution.

● Intravenous line changes no more frequently thanchange of catheters, with the exception of linechanges after the transfusion of blood orintralipids, and for discontinuous perfusions.

● A dressing change is not normally necessary.

● If local infection or phlebitis occurs, the cathetershould be removed immediately.

6.4.2 Central vascular catheters

● Clean the insertion site with an antiseptic solu-tion.

● Do not apply solvents or antimicrobial ointmentto the insertion site.

FIGURE 2. Portals of entry for microorganisms inIV systems

Reproduced by permission of Wiley&Sons, Inc. from Hospital Infec-tion Control: Principles and Practice, M. Castle, Copyright© 1980 byJohn Wiley & Sons , Inc.

● Mask, cap, and sterile gloves and gown must beworn for insertion.

● The introduction of the catheter and the subse-quent catheter dressings require a surgical handwash or rub.

● Follow appropriate aseptic care in accessing thesystem, including disinfecting external surfaces ofhub and ports.

● Change of lines should normally not occur moreoften than once every three days. A change ofline is necessary, however, after the transfusion ofblood, blood products, or intralipids, and for dis-continuous perfusions.

● Change dressing at the time of the change of lines,following surgical asepsis.

● Use a sterile gauze or transparent dressing to coverthe catheter site.

● Do not replace over a guide wire if infection issuspected.

● An increased number of catheter lumens mayincrease the risk of infection. A single lumen cath-eter is preferred wherever possible.

● Antimicrobial impregnated catheters may decreaseinfection in high-risk patients with short-term(<10 days) catheterization.

● Use the subclavion site in preference to jugularor femoral sites.

● Consider using a peripherally inserted centralcatheter, if appropriate.

6.4.3 Central vascular totally implantedcatheters

Implantable vascular access devices should be con-sidered for patients who require long-term (>30 days)therapy. Additional preventive practices for thesepatients include:

● a preoperative shower and implantation undersurgical conditions in an operating room

● local preparation includes washing and antisep-sis with major antiseptic solution as for other sur-gical procedures

● mask, hat, and sterile gloves and gown must beworn; the introduction of a catheter and the dress-ing require a surgical handwash or rub

● maintain a closed system during the use of the

Duringmanufacture

Additives

StopcockInsertion

siteSecondary

infection fromother side

Medicationport

Bottle (bag)–tubingjunction

Hairline cracksor punctures

43

device; a change of lines should normally occurevery 5 days for continuous use, and at each in-tervention for intermittent use; a change of line isnecessary after the transfusion of blood, and fordiscontinuous perfusions.

References

1. Kunin CM. Urinary tract infection detection, preventionand management, fifth edition. Baltimore, Williams& Wilkins, 1997.

2. CDC guideline for the prevention of catheter-associated urinary tract infections. Am J Infect Con-trol, 1983,11:28–33.

3. Pratt RJ et al. The epic project: Developing na-tional evidence-based guidelines for preventinghealthcare associated infections. Phase I: Guide-lines for preventing hospital-acquired infections.J Hosp Infect, 2001, 47(Supplement):S3–S4.

4. Falkiner FR. The insertion and management ofindwelling urethral catheter — minimizing the riskof infection. J Hosp Infect, 1993, 25:79–90.

5. Mangram AJ et al. Guideline for prevention ofsurgical site infection. Am J Infect Control, 1999,27:97–132.

6. Cruse PJE, Ford R. The epidemiology of woundinfections. A 10 year prospective study of 62,939wounds. Surg Clin North Am, 1980, 60:27–40.

7. Pittet D, Ducel G. Infectious risk factors related tooperating rooms. Infect Control Hosp Epidemiol, 1994,15:456–462.


8. Garibaldi R et al. The impact of preoperative skindisinfection of preventing intraoperative woundcontamination. Infect Control Hosp Epidemiol, 1988,9:109–113.

9. Dodds RDA et al. Surgical glove perforation. BritJ Surg, 1988, 75:966–968.

10. Caillot JL et al. Electronic evaluation of the valueof the double gloving. Brit J Surg, 1999, 86:1387–1390.

11. Caillaud JL, Orr NWM. A mask necessary in theoperating room? Ann R. Coll Surg Engl, 1981, 63:390–392.

12. Mayhall CG. Surgical infections including burnsin: R. P. Wenzel, ed. Prevention and Control of Nosoco-mial infections. Baltimore, Williams & Wilkins,1993:614–644.

13. Tablan OC et al. Guideline for prevention ofnosocomial pneumonia. The Hospital InfectionControl Practices Advisory Committee, Centersfor Disease Control and Prevention. Am J InfectControl, 1994, 22:247–292.

14. van Wijngaerden E, Bobbaers H. Intravascularcatheter related bloodstream infection: epidemi-ology, pathogenesis and prevention. Acta Clin Belg,1997, 52:9–18. Review.

15. Pearson ML. Guideline for prevention of intra-vascular device-related infections. Hospital In-fection Control Practices Advisory Committee.Infect Control Hosp Epidemiol, 1996, 17:438–473.

16. Health Canada. Preventing infections associatedwith indwelling intravascular access devices. CanCommun Dis Rep, 1997, 23 Suppl 8: i–iii, 1–32, i–iv,1–16.


44

CHAPTER VII

Infection control precautionsin patient care

Standard precautions for all patients (3,4)

• Wash hands promptly after contact with infectivematerial

• Use no touch technique wherever possible

• Wear gloves when in contact with blood, bodyfluids, secretions, excretions, mucous membranesand contaminated items

• Wash hands immediately after removing gloves

• All sharps should be handled with extreme care

• Clean up spills of infective material promptly

• Ensure that patient-care equipment, supplies andlinen contaminated with infective material iseither discarded, or disinfected or sterilized be-tween each patient use

• Ensure appropriate waste handling

• If no washing machine is available for linen soiledwith infective material, the linen can be boiled.

Considerations for protective clothing include:

– gown: should be of washable material, but-toned or tied at the back and protected, if nec-essary, by a plastic apron

– gloves: inexpensive plastic gloves are avail-able and usually sufficient

– mask: surgical masks made of cloth or papermay be used to protect from splashes.

7.1.2 Additional precautions for specific modesof transmission (1,2)

The following precautions are used for selectedpatients in addition to those described above:

Selected patients may require specific precautionsto limit transmission of potential infecting or-

ganisms to other patients.

Recommended isolation precautions depend on theroute of transmission (1). The main routes are:

● Airborne infection: the infection usually occursby the respiratory route, with the agent presentin aerosols (infectious particles <5 µm in diam-eter).

● Droplet infection: large droplets carry the infec-tious agent (>5 µm in diameter).

● Infection by direct or indirect contact: infectionoccurs through direct contact between the sourceof infection and the recipient or indirectly throughcontaminated objects.

7.1 Practical aspects

Isolation and other barrier precautions must beclearly written policies which are standardized, andadaptable to the infectious agent and the patients.These include:

– standard or routine precautions to be followedfor all patients

– additional precautions for selected patients.

7.1.1 Standard (routine) precautions (1,2)

To be applied to the care of all patients. This in-cludes limiting health care worker contact with allsecretions or biological fluids, skin lesions, mucousmembranes, and blood or body fluids. Health careworkers must wear gloves for each contact whichmay lead to contamination, and gowns, mask andeye protection where contamination of clothes orthe face is anticipated.

45

Airborne precautions (droplet nuclei <5 µm) (e.g.tuberculosis, chickenpox, measles) (5,6)

The following is required:

● individual room with adequate ventilation; thisincludes, where possible, negative pressure; doorclosed; at least six air exchanges per hour; ex-haust to outside away from intake ducts

● staff wearing high-efficiency masks in room

● patient to stay in room.

Droplet precautions (droplet nuclei >5 µm) (e.g. bac-terial meningitis, diphtheria, respiratory syncytialvirus)

The following procedures are required:

● individual room for the patient, if available

● mask for health care workers

● restricted circulation for the patient; patient wearsa surgical mask if leaving the room.

Contact precautions

These are required for patients with enteric infec-tions and diarrhoea which cannot be controlled, orskin lesions which cannot be contained.

● individual room for the patient if available;cohorting of patients if possible

● staff wear gloves on entering the room; a gownfor patient contact or contact with contaminatedsurfaces or material

● wash hands before and after contact with thepatient, and on leaving the room

● restrict patient movement outside the room

● appropriate environmental and equipment clean-ing, disinfection, and sterilization.

Absolute (strict) isolation (e.g. haemorrhagic fever,vancomycin-resistant S. aureus) (7,8)

Such isolation is required where there is risk of in-fection by a highly virulent or other unique agentof concern where several routes of transmission areimplicated.

● individual room, in an isolation ward if possible

● mask, gloves, gowns, cap, eye protection for allentering the room

● hygenic handwashing at entry to and exit fromthe room

● incineration of needles, syringes

● disinfection of medical instruments

● incineration of excreta, body fluids, nasopharyn-geal secretions

● disinfection of linen

● restrict visitors and staff

● daily disinfection and terminal disinfection at theend of the stay

● use of disposable (single-use) equipment

● appropriate transport and laboratory manage-ment of patient specimens.

7.2 Antimicrobial-resistant microorganisms

The increased occurrence of antimicrobial-resistantmicroorganisms (i.e. methicillin-resistant S. aureus(9,10) or vancomycin-resistant enterococci [VRE])(11,12) is a major medical concern. The spread ofmultiresistant strains of S. aureus and VRE is usuallyby transient carriage on the hands of health careworkers.

The following precautions are required for the pre-vention of spread of epidemic MRSA:

● minimize ward transfers of staff and patients

● ensure early detection of cases, especially ifadmitted from another hospital; screening of high-risk patients may be considered

● isolate infected or colonized patients in a singleroom, isolation unit or cohorting in a larger ward

● re-enforce handwashing by staff after contact withinfected or colonized patients; consider using anantiseptic handwashing agent

● use gloves for handling MRSA-contaminatedmaterials, or infected or colonized patients

● wear gown or apron when handling contaminatedmaterials or infected or colonized patients

● consider treating nasal carriers with mupirocin

● consider antiseptic detergent daily wash or bathfor carriers or infected patients

● ensure careful handling and disposal of medicaldevices, linen, waste, etc.

● develop guidelines specifying when isolationmeasures can be discontinued.

CHAPTER VII. INFECTION CONTROL PRECAUTIONS IN PATIENT CARE


46

References

1. Garner JS. Guideline for isolation precautions inhospitals. Infect Control Hosp Epidemiol, 1996, 17:54–65.

2. Health Canada. Routine practices and additionalprecautions for preventing transmission of in-fection in health care. Can Commun Dis Rep, 1999,25 Suppl 4:1–142.

3. IFIC Newsletter, December 1996, Volume 8, No. 2.

4. Guide to preventing HIV transmission in health facilities.World Health Organization Global Programmeon AIDS, 1995.

5. CDC/TB www.cdc.gov/ncidod/hip/guide/tuber.htm

6. Health Canada. Guidelines for preventing thetransmission of tuberculosis in Canadian healthcare facilities and other institutional settings. CanCommun Dis Rep, 1996, 22 S1:i–iv,1–50, i–iv,1–55.

7. CDC. Management of patients with suspectedviral hemorrhagic fever. MMWR, 1998, 37(S–3):1–6.

8. Health Canada. Canadian contingency plan forviral haemorrhagic fevers and other related dis-eases. Can Commun Dis Rep, 1997, 23 S1: i–iii ,1–13,i–iii, 1–13.

9. Ayliffe GAJ. Recommendations for the control of methi-cillin-resistant Staphylococcus aureus (MRSA).WHO/EMC/LTS/96.1.

10. Working party report. Revised guidelines for thecontrol of methicillin-resistant Staphylococcus aureusinfection in hospitals. J Hosp Infect, 1998, 39:253–290.

11. CDC recommendations for preventing the spreadof vancomycin-resistance: Recommendations ofthe Hospital Infection Control Practices AdvisoryCommittee (HICPAC). MMWR, 1995, 44(RR–12):1–12 or Infect Control Hosp Epidemiol, 1995, 16:105–113.

12. Health Canada. Preventing the spread of vanco-mycin-resistant enterococci in Canada. CanCommun Dis Rep, 1997 ,23 S8: i–iv,1–16, i–iv,1–19.

47

CHAPTER VIII

Environment

● appropriate potable water systems to limitLegionella spp.

8.1.2 Architectural segregation

It is useful to stratify patient care areas by risk of thepatient population for acquisition of infection. Forsome units, including oncology, neonatology, inten-sive care, and transplant units special ventilation maybe desirable.

Four degrees of risk may be considered:

A – Low-risk areas: e.g. administrative sections

B – Moderate-risk areas: e.g. regular patient units

C – High-risk-areas: e.g. isolation unit, intensive careunits

D – Very-high-risk areas: e.g. operating rooms

Infected patients must be separated from immuno-compromised patients. Similarly, in a central sterili-zation unit or in a hospital kitchen, contaminatedareas must not compromise non-contaminatedareas.

8.1.3 Traffic flow (3)

A room or space, whatever its purpose, is never com-pletely separate. However, a distinction can be madebetween high-traffic and low-traffic areas. One canconsider general services (food and laundry, sterileequipment, and pharmaceutical distribution), spe-cialized services (anaesthesiology, medical imaging,medical or surgical intensive care) and other areas.A hospital with well-defined areas for specificactivities can be described using flowcharts depict-ing the flow of in- or outpatients, visitors, staff(physicians, nurses and paramedics), supplies (ex-pendable, sterile, catering, clothing, etc.) as well as

The discussion of the environment will includebuilding features, ventilation, water, food and

wastes. Housekeeping and equipment are discussedin Chapter V.

8.1 Buildings

Health services — including public and private hos-pital services — must meet quality standards (ISO9000 and ISO 14000 series) (1). It is recognized thatolder facilities, and facilities in developing countries,may not be able to achieve these standards. How-ever, the principles underlying these standardsshould be kept in mind for local planning and, wherepossible, renovations should attempt to achievestandards.

8.1.1 Planning for construction or renovation(2,11)

An infection control team member should partici-pate on the planning team for any new hospital con-struction or renovation of existing facilities. The roleof infection control in this process is to review andapprove construction plans to ensure they meetstandards for minimizing nosocomial infections.Considerations will usually include:

● traffic flow to minimize exposure of high-riskpatients and facilitate patient transport

● adequate spatial separation of patients

● adequate number and type of isolation rooms

● appropriate access to handwashing facilities

● materials (e.g. carpets, floors) that can be ad-equately cleaned

● appropriate ventilation for isolation rooms andspecial patient care areas (operating theatres,transplant units)

● preventing patient exposure to fungal spores withrenovations


48

the flow of air, liquids and wastes. Other traffic pat-terns may also be identified. Building or rebuildinga hospital requires consideration of all physicalmovements and communications, and where con-tamination may occur.

In this context, rather than considering a “clean” anda “dirty” circuit, consider only circuits where thedifferent flows can cross without risk provided ma-terial is properly protected. An elevator can accom-modate hospital staff, sterile equipment, visitors andwaste, as long as each of these is treated appropri-ately. Both sterile products and waste must be sealedin safe containers, and the outside of those contain-ers must present no risk of biological contamina-tion.

8.1.4 Materials

The choice of construction materials — especiallythose considered in the covering of internal surfaces— is very important. Floor coverings must be easy toclean and resistant to disinfection procedures. Thisalso applies to all items in the patient environment.

All of this calls for:

1. Definition of needs (planning)

2. Definition of the level of risk (segregation)

3. Description of functional flow patterns (flows andisolation)

4. Building or rebuilding (materials)

8.2 Air

8.2.1 Airborne contamination and transmission

Infection may be transmitted over short distancesby large droplets, and at longer distances by dropletnuclei generated by coughing and sneezing (4). Drop-let nuclei remain airborne for long periods, may dis-seminate widely in an environment such as a hospitalward or an operating room, and can be acquired by(and infect) patients directly, or indirectly throughcontaminated medical devices.

Housekeeping activity such as sweeping, using drydust mops or cloths, or shaking out linen, can aero-solize particles that may contain microorganisms.Similarly, Legionella pneumophila, the organism respon-sible for legionellosis (Legionnaires’ disease; Pontiacfever), can become airborne during the evaporation

of water droplets from air conditioning cooling tow-ers or with aerosolization in patient showers, andsubsequently may be inhaled by patients at risk ofinfection.

The number of organisms present in room air willdepend on the number of people occupying theroom, the amount of activity, and the rate of air ex-change. Bacteria recovered from air samples usuallyconsist of Gram-positive cocci originating from theskin. They can reach large numbers if dispersed froman infected lesion, particularly an infected exfolia-tive skin lesion. However, since the contaminatedskin scales are relatively heavy, they do not remainsuspended in the air for long. Gram-negative bacte-ria are usually found in the air only when associ-ated with aerosols from contaminated fluids, andtend to die on drying.

Droplets projected from the infected upper respira-tory tract may contain a wide variety ofmicrorganisms, including viruses, and many infec-tions can be spread by this route (i.e. respiratory vi-ruses, influenza, measles, chickenpox, tuberculosis).In most cases, these are spread by large droplets,and an infective dose will rarely move more than afew feet from the source patient. Varicella-zoster(chickenpox), tuberculosis, and a few other agents,however, may be transmitted over large distances indroplet nuclei.

8.2.2 Ventilation

Fresh filtered air, appropriately circulated, willdilute and remove airborne bacterial contamination.It also eliminates smells. Desirable ventilation rates,expressed in air changes per hour, vary with thepurpose of a particular area (5). High-risk hospitalareas (operating rooms, nurseries, intensive careunits, oncology, and burn units) should have air withminimal bacterial contamination.

● Adequate ventilation systems require proper de-sign and maintenance to minimize microbial con-tamination. All outdoor air inlets must be locatedas high as possible above ground level; inlets mustbe remote from ventilation discharge outlets,incinerators, or boiler stacks.

● Within rooms, the location of air inlets and ex-haust outlets influences the movement of air. Highwall or ceiling inlets and low wall outlets allowclean air to move downward through the areatoward the contaminated floor where it is removedthrough the low exhaust. This pattern is for all

49

areas where high-risk patients receive care, andin areas subject to heavy contamination.

● Filters used in the ventilation systems must meetstandards for the patient care activity of the area.High-efficiency filters must be provided in sys-tems serving areas where patients are particularlysusceptible to infection (haematology/oncologyunits) or where some clinical procedures subjectpatients to unusual hazard (for instance surgicalprocedure, particularly transplantation).

● Regular inspection and maintenance of filters,humidifiers, and grills in the ventilation systemmust be performed and documented.

● Cooling towers and humidifiers should be regu-larly inspected and cleaned to prevent aerosoli-zation of Legionella spp.

● Zoning of air systems may confine the air of adepartment to that department alone. A designthat enables air pressure to control air movementinto or out of a specific room or area will controlthe spread of contamination. Positive air pressureis recommended for areas which must be as cleanas possible. It is achieved by supplying more airinto an area than can be removed by the exhaustventilation system. This produces an outflowaround doors and other openings, and decreasesentry of air from more contaminated areas. Nega-tive air pressure is recommended for contami-nated areas, and is required for isolation ofpatients with infections spread by the airborneroute. It is achieved by supplying less air to thearea than can be removed by the ventilation sys-tem. Negative air pressure produces an inflowaround openings and reduces the movement ofcontaminated air out of the area. For effective airpressurization all doors must be kept closed ex-cept for essential entrances and exits.

8.2.3 Operating theatres

Modern operating rooms which meet current airstandards are virtually free of particles larger than0.5 µm (including bacteria) when no people are inthe room. Activity of operating room personnel isthe main source of airborne bacteria, which origi-nate primarily from the skin of individuals in theroom. The number of airborne bacteria depends oneight factors (Table 1). Conventional operating roomsare ventilated with 20 to 25 changes per hour ofhigh-efficiency filtered air delivered in a vertical flow.High-efficiency particulate air (HEPA) systems re-

move bacteria larger than 0.5 to 5 µm in diameterand are used to obtain downstream bacteria-free air.The operating room is usually under positive pres-sure relative to the surrounding corridors, to mini-mize inflow of air into the room.

TABLE 1. Factors influencing airborne contamina-tion in operating theatres

1. Type of surgery

2. Quality of air provided

3. Rate of air exchange

4. Number of persons present in operating theatre

5. Movement of operating room personnel

6. Level of compliance with infection control practices

7. Quality of staff clothing

8. Quality of cleaning process

8.2.4 Ultra-clean air

● For minimizing airborne particles, air must be cir-culated into the room with a velocity of at least0.25 m/sec through a high-efficiency particulateair (HEPA) filter, which excludes particulate mat-ter of defined size. If particles 0.3 microns indiameter and larger are removed, the air enteringthe room will be essentially clean and free of bac-terial contaminants.

● This principle has been applied to microbiologylaboratories, pharmacies, special intensive careunits, and operating rooms.

Workers in microbiology laboratories use specialunidirectional airflow hoods to handle microbialcultures. These are particularly useful for certainhighly infectious cultures. Hoods of this type pro-tect the individual worker as well as the labora-tory environment from contamination by theairborne route.

Similar hoods are used in pharmacies to preventairborne contamination of sterile fluids whencontainers are opened. For example, when add-ing an antibiotic to a container of sterile glucosesolution for intravenous use, or when preparingfluids for parenteral hyperalimentation.

In intensive care units, laminar flow units havebeen used in the treatment of immunosuppressedpatients.

For operating theatres, a unidirectional clean air-flow system with a minimum size of 9 m2 (3 m x

CHAPTER VIII. ENVIRONMENT


50

3 m) and with an air speed of at least 0.25 m/s,protects the operating field and the instrumenttable. This ensures instrument sterility through-out the procedure. It is possible to reduce the costsof building and maintaining operating theatresby positioning such systems in an open space withseveral operating teams working together. This isparticularly adapted to high-risk surgery such asorthopaedics, vascular surgery, or neurosurgery.

Some nosocomial infections are due to airborne mi-croorganisms.

Appropriate ventilation is necessary, and must bemonitored within risk areas, e.g. orthopaedics, vascu-lar surgery and neurosurgery.

Unidirectional airflow systems should be incorporatedin appropriate areas in new hospital construction.

8.3 Water

The physical, chemical and bacteriological charac-teristics of water used in health care institutions mustmeet local regulations. The institution is responsi-ble for the quality of water once it enters the build-ing. For specific uses, water taken from a publicnetwork must often be treated for medical use (physi-cal or chemical treatment). Criteria for drinking-water is usually not adequate for medical uses ofwater.

8.3.1 Drinking-water

Drinking-water should be safe for oral ingestion.National norms and international recommendationsdefine appropriate criteria for clean drinking-water.Unless adequate treatment is provided, faecal con-tamination may be sufficient to cause infectionthrough food preparation, washing, the general careof patients, and even through steam or aerosol in-halation (Legionella pneumophila). Even water that con-forms to accepted criteria may carry potentiallypathogenic microorganisms. Organisms present intap water have frequently been implicated in noso-comial infections (Table 2). Guidance on drinking-water quality is provided in WHO guidelines (6).

These microorganisms have caused infection ofwounds (burns, surgical wounds), respiratory tract,and other sites (semi-critical equipment such asendoscopes rinsed with tap water after they havebeen disinfected).

TABLE 2. Some microorganisms causingwaterborne nosocomial infections

Gram-negative bacteria:

Pseudomonas aeruginosa

Aeromonas hydrophilia

Burkholderia cepacia

Stenotrophomonas maltophilia

Serratia marcescens

Flavobacterium meningosepticum

Acinetobacter calcoaceticus

Legionella pneumophila and other

Mycobacteria:

Mycobacterium xenopi

Mycobacterium chelonae

Mycobacterium avium-intracellularae

Legionella spp. live in hot water networks where thetemperature promotes their development withinprotozoan phagosomes; tap aerators facilitate pro-liferation of these and other microorganisms, suchas Stenotrophomonas maltophilia. Equipment which usestap water may be a risk in health care institutions:ice machines, dental units, eye- and ear-washinginstallations, etc. Water used for flowers and holywater has also been implicated in nosocomial infec-tions.

8.3.2 Baths

Baths can be used either for hygiene (patients,babies) or for specific purposes of care (burns, re-habilitation in swimming pools, lithotripsy). Themain infectious agent in baths is Pseudomonasaeruginosa (7). It may cause folliculitis (generallybenign), external otitis, which can become severeunder certain conditions (diabetes, immunosuppres-sion), and wound infections. Baths can also transmitother pathogens (Legionella, atypical mycobacteria —with swimming pool granuloma, enterobacteria suchas Citrobacter freundii).

Viral infections may also be transmitted in commu-nal baths (Molluscum contagiosum, papillomavirus)through contact with contaminated surfaces. Para-sitic infections such as cryptosporidiosis, giardiasis,and amoebiasis, and mycoses, especially Candida, mayalso be transmitted. National regulations for publicswimming pools and baths is a basis for standardsfor health care institutions. Protocols for the disin-fection of equipment and material must be written,

51

and adherence to these practices monitored. Infectedpatients should be restricted from using communalbaths. Potential entry points for organisms to causeinfection in patients, such as percutaneous devices,must be protected with waterproof occlusive dress-ings.

8.3.3 Pharmaceutical (medical) water

There are physical, chemical, bacteriological, andbiological parameters which must be met for waterused for medical purposes.

Pharmaceutical waters include (8):

● purified water — sterile water used for the prepa-ration of drugs that normally do not need to besterile, but must be pyrogen-free

● water used for injectable preparations, which mustbe sterile

● dilution water for haemodyalisis.

In the case of dialysis, contamination may induceinfections (bacteria passing from the dialysate intothe blood) or febrile reactions due to pyrogenicendotoxins from the degradation of the mem-branes of Gram-negative bacteria. The CDC rec-ommends that the water for haemodyalisiscontain:

— less than 200 coliforms/ml for water used fordilution

— less than 2000 coliforms/ml for dialysate.

The levels of organisms in dialysate should bemonitored once a month. The coliform recom-mendations may be revised downwards withimprovements in water production, use of dialy-sis membranes with improved permeability, andincreasing knowledge of the role of bacterial prod-ucts in the complications of long-term dialysis.New techniques (haemofiltration, haemodialysisfiltration on line) require stricter guidelines forwater dilution and for haemodialysis solutions(9).

8.3.4 Microbiological monitoring

Regulations for water analysis (at the national levelfor drinking-water, in the Pharmacopoeia for phar-maceutical waters) define criteria, levels of impuri-ties, and techniques for monitoring. For water usefor which regulations are not available, parametersshould be appropriate for the planned use and the

requirements of users (including risk factors forpatients).

Methods used for monitoring must suit the use. Bac-teriological, medical and biochemical methods arenot necessarily adapted to environmental analyses,and may lead to falsely reassuring conclusions. Twopoints which must be considered for water ecosys-tems are: (1) biofilm, (2) level of stress for the micro-organism (nutrients, exposure to physical or chemicalantibacterial agents).

Biofilm consists of microorganisms (dead or alive)and macromolecules of biological origin, and accu-mulates as a complex gel on the surfaces of con-duits and reservoirs. It is a dynamic ecosystem witha wide variety of organisms (bacteria, algae, yeasts,protozoa, nematodes, insect larvae, molluscs) start-ing with the biodegradable organic matter of water.This biofilm is a dynamic reservoir for microorgan-isms (including pathogenic agents such as Legionellaand Pseudomonas aeruginosa). Individual organismsmay be freed into circulation through shearing atthe surface of the biofilm or through the mechani-cal impact of vibrations (such as may occur duringconstruction).

Bacteriological tests may not always give true esti-mates of contamination because of the presence ofagents such as disinfectants.

Water is used in health care institutions for manyvery different uses.

The use determines characteristics needed for thewater. These usually differ from those of tap water.

Infections attributable to water are usually due tofailure to meet water quality standards for the spe-cific use.

Infection control/hygiene teams must have written,valid policies for water quality to minimize risk ofadverse outcomes attributable to water in health caresettings.

8.4 Food

Quality and quantity of food are key factors for pa-tient convalescence. Ensuring safe food is an impor-tant service delivery in health care.



52

8.4.1 Agents of food poisoning and foodborneinfections

Bacterial food poisoning (acute gastroenteritis) is aninfection or intoxication manifested by abdominalpain and diarrhoea, with or without vomiting or fe-ver. The onset of symptoms may range from less thanone to more than 48 hours after eating contami-nated food. Usually, large numbers of organismsactively growing in food are required to initiatesymptoms of infection or intoxication. Water, milk,and solid foods are all vehicles for transmission.

Table 3 is a non-exhaustive listing of organisms thatmay cause food poisoning.

TABLE 3. Microbiological agents causing foodpoisoning

BacteriaSalmonella species Campylobacter jejuniStaphylococcus aureus Yersinia enterocoliticaClostridium perfringens Vibrio parahaemolyticusClostridium botulinum Vibrio choleraeBacillus cereus and other Aeromonas hydrophilia

aerobic spore-forming Streptococcus speciesbacilli Listeria monocytogenes

Escherichia coli

Viruses ParasitesRotavirus Giardia lambliaCaliciviruses Entamoeba histolytica

8.4.2 Factors contributing to food poisoning

The frequency of foodborne illness is increasing. Thismay be due to increasing complexity in modern foodhandling, particularly in mass-catering, as well asincreasing importation of potentially contaminatedfood products from other countries.

For individuals to develop food poisoning, thenumber of organisms in food must be of a sufficientlevel. There must also be adequate nutrients, mois-ture, and warmth for multiplication of organisms,or toxin production to occur between preparationand consumption of the food.

Many inappropriate food handling practices permitcontamination, survival and growth of infecting bac-teria. The most common errors which contribute tooutbreaks include:

— preparing food more than a half day in ad-vance of needs

— storage at room temperature

— inadequate cooling

— inadequate reheating

— use of contaminated processed food (cookedmeats and poultry, pies and take-away meals)prepared in premises other than those in whichthe food was consumed

— undercooking

— cross-contamination from raw to cooked food

— contamination from food handlers.

Hospital patients may be more susceptible to food-borne infection, and suffer more serious conse-quences than healthy people. Thus, high standardsof food hygiene must be maintained. A hospital sur-veillance system must be able to identify potentialfoodborne outbreaks early (Chapter III), and promptoutbreak investigation and control must be initi-ated if an outbreak is suspected (Chapter IV).

8.4.3 Prevention of food poisoning

The following food preparation practices must behospital policy, and rigorously adhered to:

● Maintain a clean work area.

● Separate raw and cooked food to avoid cross-contamination.

● Use appropriate cooking techniques and followrecommendations to prevent growth of micro-organisms in food.

● Maintain scrupulous personal hygiene amongfood handlers, especially handwashing, as handsare the main route of contamination (see Chapter6).

● Staff should change work clothes at least once aday, and keep hair covered.

● Avoid handling food in the presence of an infec-tious disease (cold, influenza, diarrhoea, vomit-ing, throat and skin infections), and report allinfections.

Other factors important for quality control are:

● Purchased food must be of good quality (con-trolled), and bacteriologically safe.

● Storage facilities must be adequate, and corre-spond to requirements for the food type.

● The quantity of perishable goods should notexceed an amount corresponding to one day’sconsumption.

53

● Dry goods, preserves, and canned food should bestored in dry, well-ventilated storerooms, andstocks rotated.

● Frozen food storage and preparation must followproducers instructions, and be kept at tempera-tures of at least -18 °C (-0.4 °F); do not refreeze.

● The catering system environment must be washedoften and regularly with tap water and appropri-ate detergents (and/or disinfectants).

● Samples of prepared food should be stored for aspecified time period, to allow retrieval for test-ing should an outbreak occur.

● Food handlers should receive continuing instruc-tion in safe practices.

Food poisoning can be avoided by basic principles offood care:

• Limiting contamination from source, hands, rawfood, and environment

• Purchasing• Storage• Refrigeration• Cooking• Personal hygiene• Clean up• Pest control

8.5 Waste

Health care waste is a potential reservoir of patho-genic microorganisms, and requires appropriate han-dling. The only waste which is clearly a risk fortransmission of infection, however, is sharps con-taminated with blood. Recommendations for classi-fication and handling of different types of wasteshould be followed (10).

8.5.1 Definition and classification (10)

Health care waste includes all waste generated byhealth care establishments, research facilities, andlaboratories.

Between 75% to 90% of this waste is non-risk or “gen-eral” health care waste, comparable to domesticwaste. This comes from the administrative andhousekeeping functions of health care facilities. Theremaining 10–25% of health care waste is regardedas hazardous, and may create some health risks(Table 4).

Infectious waste is suspected to contain pathogens(bacteria, viruses, parasites, or fungi) in sufficientconcentrations or quantities to cause disease in sus-ceptible hosts. This category of waste includes:

● cultures and stocks of infectious agents from labo-ratory work


TABLE 4. Categories of health care waste

Waste category Description and examples

Infectious waste Waste suspected to contain pathogens, e.g. laboratory cultures; waste fromisolation wards; tissues (swabs), materials, or equipment that have been incontact with infected patients; excreta

Pathological waste Human tissues or fluids, e.g. body parts; blood and other body fluids; fetuses

Sharps Sharp waste, e.g. needles; infusion sets; scalpels; knives; blades; broken glass

Pharmaceutical waste Waste containing pharmaceuticals, e.g. pharmaceuticals that are expired orno longer needed; items contaminated by or containing pharmaceuticals(bottles, boxes)

Cytotoxic waste Waste containing substances with genotoxic properties, e.g. waste contain-ing cytostatic drugs (often used in cancer therapy); genotoxic chemicals

Chemical waste Waste containing chemical substances, e.g. laboratory reagents; film devel-oper; disinfectants that are expired or no longer needed; solvents

Wastes with high content of heavy metals Batteries; broken thermometers; blood pressure gauges; etc.

Pressurized containers Gas cylinders; gas cartridges; aerosol cans

Radioactive waste Waste containing radioactive substances, e.g. unused liquids from radio-therapy or laboratory research; contaminated glassware, packages, orabsorbent paper; urine and excreta from patients treated or tested withunsealed radionucleotides; sealed sources


54

● waste from surgery and autopsies on patients withinfectious diseases (e.g. tissues, and materials orequipment that have been in contact with bloodor other body fluids)

● waste from infected patients in isolation wards(e.g. excreta, dressings from infected or surgicalwounds, clothes heavily soiled with human bloodor other body fluids)

● waste that has been in contact with infectedpatients undergoing haemodialysis (e.g. dialysisequipment such as tubing and filters, disposabletowels, gowns, aprons, gloves and laboratory coats)

● infected animals from laboratories

● any other instruments or materials that have beencontaminated by infected persons or animals.

8.5.2 Handling, storage and transportation ofhealth care waste

All waste disposal practices must meet local regula-tions. The following practices are recommended as ageneral guide:

● For safety and economic reasons, health care in-stitutions must organize a selective collection ofhospital waste, differentiating between medicalwaste, general waste and some specific wastes(sharp instruments, highly infectious waste, cytoxicwaste).

● General health care waste may be disposed in thestream of domestic refuse.

● Sharps should be collected at source of use inpuncture-proof containers (usually made of metalor high-density plastic) with fitted covers. Con-tainers should be rigid, impermeable, and punc-ture proof. To discourage abuse, containers shouldbe tamper-proof (difficult to open or break).Where plastic or metal containers are unavail-able or too costly, containers made of dense card-board are recommended — these fold for ease oftransport and may be supplied with a plasticlining.

● Bags and other containers used for infectiouswaste must be marked with the international in-fectious substance symbol.

● Infectious health care waste should be stored in asecure place with restricted access.

● Microbiological laboratory waste should be steri-lized by autoclaving. It must be packaged in bagscompatible with the process: red bags, suitablefor autoclaving, are recommended.

● Cytotoxic waste, most of which is produced inmajor hospital or research facilities, must be col-lected in strong, leak-proof containers clearlylabelled “Cytotoxic wastes”.

● Small amounts of chemical or pharmaceuticalwaste may be collected together with infectiouswaste.

● Large quantities of obsolete or expired pharma-ceuticals stored in hospital wards or departmentsmust be returned to the pharmacy for disposal.Other pharmaceutical waste generated at thewards, such as spilled or contaminated drugs, orpackaging containing drug residues must not bereturned because of the risk of contaminating thepharmacy; it must be deposited in the correctcontainer at the point of generation.

● Large quantities of chemical waste must be packedin chemical-resistant containers and sent to spe-cialized treatment facilities (if available). The iden-tity of the chemicals must be clearly marked onthe containers: hazardous chemical wastes ofdifferent types should never be mixed.

● Waste with a high content of heavy metals (e.g.cadmium or mercury) must be collected and dis-posed of separately.

● Pressurized containers may be collected with gen-eral health care waste once they are completelyempty, provided that the waste is not destinedfor incineration.

● Low-level radioactive infectious waste (e.g. swabs,syringes for diagnostic or therapeutic use) maybe collected in yellow bags or containers forinfectious waste if these are destined for incin-eration.

● Health care personnel and other hospital work-ers should be informed about the hazards relatedto health care waste and trained in appropriatewaste management practices.

● Additional information on collection, handling,storage and disposal of health care wastes, as wellas personal protection and training issues is pro-vided in a referenced document (10).

55

8. American Society of Hospital Pharmacists. ASHPtechnical assistance bulletin on quality assurancefor pharmacy-prepared sterile products. Am J HospPharm, 1993, 50:2386–98.

9. Ministère français des Affaires sociales etsanitaires. Circulaire DGS/DH/AFSSAPS No.311du 7 juin 2000 relative aux spécifications tech-niques et à la sécurité sanitaire de la pratique del’hémofiltration et de l’hémodiafiltration en lignedans les établissements de santé. Circulaire DGS/DH/AFSSAPS No 337 du 20 juin 2000 relative à ladiffusion d’un guide pour la production d’eaupour l’hémodialyse des patients insuffisantsrénaux.

10. Prüss A, Giroult B, Rushbrook P. Safe managementof wastes from health-care activities. Geneva, WHO,1999.

11. American Institute of Architects. Guidelines fordesign and construction of hospital and health care facili-ties. Washington, American Institute of ArchitectsPress, 2001.


References

1. ISO — rue de Varembé 1, CH 1200 Geneva.www.iso.ch

2. Limacher H. Construction hospitalière — Guide deplanification. Département de la Santé publiquedu Canton de Zurich.

3. Ducel G. Comment penser une construction ouune reconstruction hospitalière? Hygiènes, 1993,1:46–49.

4. Knight MD. Airborne transmission and pulmonarydeposition of respiratory viruses — Airborne transmissionand airborne infection. Enschede, Oosthoek Publish-ing Company, 1973:175–183.

5. Guide Uniclima — Traitement de l’air en milieu hospitalier.Paris, Editions SEPAR. ISBN 2.951 117.0.3.

6. World Health Organization. Guidelines for drinking-water quality, Vol. 1, Recommendations, 2nd edition.Geneva, WHO, 1993.

7. Pollack M. Pseudomonas aeruginosa in principles andpractices of infectious diseases, 4th ed. New York,Churchill-Livingstone, 1995, chapter 197.


56

CHAPTER IX

Antimicrobial use andantimicrobial resistance

Following the discovery and widespread use ofsulfonamides and penicillin in the mid-20th cen-

tury, the years between 1950 and 1970 saw a “goldenage” of antimicrobial discovery (Table 1) . Many in-fections that were once serious and potentially fatalcould now be treated and cured. However, thesesuccesses encouraged the overuse and misuse ofantibiotics. Currently many microorganisms havebecome resistant to different antimicrobial agents,and in some cases to nearly all agents. Resistant bac-teria may cause increased morbidity and death,particularly among patients with significant under-lying diseases or who are immunocompromised.Resistance to antimicrobial agents is a problem inthe community as well as health care facilities, butin hospitals, transmission of bacteria is amplified be-cause of the highly susceptible population.

Resistance and its spread among bacteria is gener-ally the result of selective antibiotic pressure (1,2).Resistant bacteria are transmitted among patients,and resistance factors are transferred between bac-teria, both occurring more frequently in health caresettings. The continuous use of antimicrobial agentsincreases selection pressure favouring the emergence,multiplication, and spread of resistant strains. Inap-propriate and uncontrolled use of antimicrobialagents including overprescribing, administration ofsuboptimal doses, insufficient duration of treatment,and misdiagnosis leading to inappropriate choice ofdrug, contribute to this. In health care settings, thespread of resistant organisms is facilitated whenhandwashing, barrier precautions, and equipmentcleaning are not optimal. The emergence of resist-ance is also favoured by underdosing due to short-age of antibiotics, where lack of microbiologicallaboratories results in empiric prescribing, and wherethe lack of alternate agents compounds the risk oftherapeutic failure.

TABLE 1. Commonly used antimicrobials by class

Class Antibiotics

Aminoglycosides Streptomycin, kanamycin,tobramycin, gentamicin,neomycin, amikacin

Beta-lactams

• Penicillins Benzylpenicillin (penicillin G),procaine-benzyl penicillin,benzathine-benzyl penicillin,phenoxymethylpenicillin(penicillin V), ampicillin,amoxycillin, methicillin,cloxacillin

• Penicillin/beta- amoxicillin/clavulanic acid,lactamase inhibitors piperacillin/tazobactam

• Cephalosporins 1st generation: cephalexin,cephalothin

2nd generation: cefuroxime,cefoxitin, cefaclor

3rd generation: cefotaxime,ceftriaxone, ceftazidime

Other beta-lactams Aztreonam,

• Carbapenems Imipenem, meropenem

• Glycopeptides Vancomycin, teicoplanin

• Macrolides/azolides Erythromycin, oleandomycin,spiramycin, clarithromycin,azithromycin

• Tetracyclines Tetracycline, chlortetracycline,minocycline, doxycycline,oxytetracycline

• Quinolones Nalidixic acid, ciprofloxacin,norfloxacin, pefloxacin,sparfloxacin, fleroxacin,ofloxacin, levofloxacin,gatifloxacin, moxifloxacin

• Oxazolidinone linezolid

• Streptogramin Quinupristin/dalfopristin

• Others Bacitracin, cycloserine,novobiocin, spectinomycin,clindamycin, nitrofurantoin

Sulfonamides and Trimethoprim, trimethoprim/trimethoprim sulfamethoxazole

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9.1 Appropriate antimicrobial use

Each health care facility should have an antimicro-bial use programme (3,4). The goal is to ensureeffective economical prescribing to minimize theselection of resistant microorganisms. This policymust be implemented through the Antimicrobial UseCommittee.

● Any antibiotic use must be justifiable on the ba-sis of the clinical diagnosis and known or expectedinfecting microorganisms.

● Appropriate specimens for bacteriological exami-nation must be obtained before initiating antibi-otic treatment, to confirm the treatment isappropriate.

● The selection of an antibiotic must be based notonly on the nature of the disease and that of thepathogenic agent(s), but on the sensitivity pat-tern, patient tolerance, and cost.

● The physician should receive timely, relevant in-formation of the prevalence of resistance in thefacility.

● An agent with as narrow a spectrum as possibleshould be used.

● Antibiotic combinations should be avoided, ifpossible.

● Selected antibiotics may be restricted in use.

● The correct dose must be used. Low dosages maybe ineffective for treating infection, and encour-age the development of resistant strains. On theother hand, excessive doses may have increasedadverse effects, and may not prevent resistance.

Generally speaking, a course of antibiotics shouldbe of limited duration (5-14 days), depending on thetype of infection. There are selected indications forlonger courses. As a rule, if an antibiotic has notbeen effective after three days of therapy, the anti-biotic should be discontinued and the clinical situ-ation reassessed.

9.1.1 Therapy

Empirical antimicrobial therapy must be based oncareful clinical evaluation and local epidemiologi-cal data regarding potential pathogens and antibi-otic susceptibility. Appropriate specimens for Gramstain, culture and, if available, sensitivity testing mustbe obtained before starting therapy. Therapy selectedshould be effective, limit toxicity, and be of the nar-

CHAPTER IX. ANTIMICROBIAL USE AND ANTIMICROBIAL RESISTANCE

rowest spectrum possible. The choice of parenteral,oral or topical antimicrobial formulations is madeon the basis of clinical presentation (site and sever-ity of infection). Oral administration is preferred, ifpossible. Combinations of antibiotics should be usedselectively and only for specific indications such asenterococcal endocarditis, tuberculosis, and mixedinfections.

The physician must decide whether antibiotictherapy is really necessary. In patients with fever,non-infectious diagnoses must be considered.

The aim of antimicrobial therapy is to choose a drugthat is selectively active against the most likelypathogen(s) and the least likely to cause adverseeffects or promote resistance.

9.1.2 Chemoprophylaxis

Antibiotic prophylaxis is used only when it has beendocumented to have benefits which outweigh risks.Some accepted indications include:

● selected surgical prophylaxis (Table 2)

● endocarditis prophylaxis.

Where chemoprophylaxis is appropriate, antibioticsmust be initiated intravenously within one hour priorto the intervention. It is often most efficient to ordertherapy given at call to the operating room or at thetime of induction of anaesthesia. In most cases,prophylaxis with a single preoperative dose is suffi-cient. The regimen selected depends on the prevail-ing pathogen(s), the pattern of resistance in thesurgical service, the type of surgery, the serum half-life of the antibiotic, and the cost of the drugs.Administration of prophylactic antibiotics for alonger period prior to the operation is counterpro-ductive, as there will be a risk of infection by a re-sistant pathogen.

Antibiotic prophylaxis is not a substitute for appro-priate aseptic surgical practice.

9.2 Antimicrobial resistance

Nosocomial infections are often caused by antibi-otic-resistant organisms. Where transmission of theseorganisms in the health care setting is occurring,specific control measures are necessary (Table 3,Table 4). Antimicrobial restriction is also an impor-tant intervention.


58

TABLE 3. Infection control measures forcontainment of outbreaks withantimicrobial-resistant organisms

Identify reservoirs

Colonized and infected patients

Environmental contamination

Halt transmission

Improve handwashing and asepsis

Isolate colonized and infected patients

Eliminate any common source; disinfect environment

Separate susceptible from infected and colonizedpatients

Close unit to new admissions, if necessary

Modify host risk

Discontinue compromising factors when possible

Control antibiotic use (rotate, restrict, or discon-tinue)

TABLE 4. Control of endemic antibiotic resistance

• Ensure appropriate use of antibiotics (optimalchoice, dosage and duration of antimicrobialtherapy and chemoprophylaxis based on definedhospital antibiotic policy, monitoring andantibiotic resistance, and up-to-date antimicro-bial guidelines).

• Institute protocol (guidelines) for intensiveinfection control procedures and provideadequate facilities and resources, especially forhandwashing, barrier precautions (isolation), andenvironmental control measures.

• Improve antimicrobial prescribing practicesthrough educational and administrative methods.

• Limit use of topical antibiotics.

9.2.1 MRSA (methicillin-resistantStaphylococcus aureus)

Some strains of methicillin-resistant Staphylococcusaureus (MRSA) have a particular facility for nosoco-mial transmission. MRSA strains are often resistantto several antibiotics in addition to the penicillinase-resistant penicillins and cephalosporins, and occa-sionally are sensitive only to vancomycin andteicoplanin. MRSA infections are similar to thosecaused by sensitive strains of S. aureus, e.g. woundinfections, lower respiratory and urinary tract infec-tions, septicaemia, infections of sites for invasivedevices, pressure sores, burns, and ulcers. Severe

TABLE 2. Recommendations for antibioticprophylaxis in surgery (5,6,7,8)

Type of surgery Prophylaxis

Gastrointestinal Single dose:Oesophageal, cephalothin/cefazolin 2 g orgastric, duodenal cefuroxime 1.5 g or

piperacillin 4 g or

Biliary tract above anddoxycycline 200 mg

Pancreatic, intestinal any of above andmetronidazole 1 g ortinidazole 800 mg

Urological Single dose:Prostatectomy cefuroxime 1.5 g or

ciprofloxacin 500 mg ornorfloxacin 500 mg orTMP/SMX* 160/800 mg

Enteric substitutes same as intestinalImplanted prosthesis cefuroxime 1.5 gTransrectal prostate ciprofloxacin 500 mg or

biopsy norfloxacin 400 mg

Gynaecological/ Single dose:obstetrical

Total hysterectomy cefuroxime 1.5 g orcefazolin 2 g orpiperacillin 4 g

Orthopaedic 3–4 doses over 24 hrsJoint replacement cloxacillin/nafcillinOsteosynthes of 1–2 g/dose

trochanteric femur cephalothin/cefazolinfractures 1-2 g/dose or

Amputations clindamycin 600 mg/dose

VascularReconstructive cefuroxime 1.5 g q8h forAmputations 24 hours orAortic graft stents ciprofloxacin 750 mg q12h for

24 hours or**vancomycin 1 g q12h for

24 hours

Thoracic 3–4 doses over 24 hrsCardiac cephalothin/cefazolin 2 g orImplantation cloxacillin/nafcillin 2 g or

pacemaker/ clindamycin 600 mg ordefibrillator **vancomcyin 1 g IV(2 doses)

Pulmonary cephalothin/cefazolin 2 g orcefuroxime 1.5 g orbenzylpenicillin 3 g orclindamycin 600 mg

* TMP/SMX: Trimethoprim/sulfamethoxazole

** For penicillin-allergic only

59

formulary, prescribing policies, reviews and approvespractice guidelines, audits antibiotic use, overseeseducation, and interacts with pharmaceutical repre-sentatives. The committee must be multidisciplinary,and should include: infectious disease physicians,surgeons, infection control nurses, pharmacists,microbiologists, and administration as well as otherrelevant professionals.

Each hospital will develop its own antibiotic policy,usually including classification of antimicrobialagents into the following categories:

● unrestricted (effective, safe and inexpensive, e.g.benzyl penicillin)

● restricted or reserved (to be used only in specialsituations by selected practitioners with exper-tise, for severe infection, with particular patternof resistance, etc.)

● excluded (preparations without additional ben-efit to other, less costly alternatives).

The Antimicrobial Use Committee will usually be asubcommittee of the Pharmacy and TherapeuticsCommittee.

Hospitals should have a simple, flexible and regularlyupdated antibiotic-prescribing policy on a disease-specific basis, relying whenever possible on knowl-edge of prevailing antibiotic-sensitivity patterns andcontrolled use of reserve antibiotics. This shouldincorporate local practice guidelines.

9.3.2 Role of the microbiology laboratory

The microbiology laboratory has a major role inantimicrobial resistance. This includes:

● perform antibiotic susceptibility testing of appro-priate microbial isolates consistent with standards

● determine which antimicrobials are tested andreported for each organism

● provide additional antimicrobial testing for se-lected resistant isolates, as requested

● participate in activities of the Antimicrobial UseCommittee

● monitor and report trends in prevalence of bac-terial resistance to antimicrobial agents

● provide microbiological support for investigationsof clusters of resistant organisms

CHAPTER IX. ANTIMICROBIAL USE AND ANTIMICROBIAL RESISTANCE

infections are most common in the intensive careand other high-risk units with highly-susceptiblepatients (e.g. burn and cardiothoracic units). Epidemicspread of MRSA may occur; highly-transmissiblestrains tend to spread regionally and nationally tomany hospitals. Factors increasing the likelihood ofacquisition of resistant organisms are shown in thefollowing box (9).

Patient risk factors for MRSA

• Possible sites of colonization or infection: nose,throat, perineum, inguinal folds, less frequentlyvagina or rectum; skin of buttocks area in immo-bile patients (superficial skin lesions, pressure sores,ulcers, dermatitis); surgical wounds and burns; in-vasive devices (intravascular and urinary catheters,stoma tubes, tracheostomy tubes).

• Prolonged hospital stay.

• Elderly patients, particularly with reduced mobil-ity, immunosuppression or previous antibiotictherapy.

• Patients in special units, e.g. intensive care unit(ICU) and burns or referral hospitals.

• Frequent transfers of patients and staff betweenwards or hospitals.

• Excessive use of antibiotics in unit.

• Patient overcrowding.

• Staff shortages.

• Inadequate facilities for handwashing and appro-priate isolation.

9.2.2 Enterococci

Some enterococci are now resistant to all antibioticsexcept vancomycin (VRE). The combination of peni-cillin and glycopeptide resistance in Enterococcusfaecium causes infections which cannot be effectivelytreated. Fortunately, most VRE cause colonization,not infection. When infection does occur, it may notbe treatable with antibiotics.

9.3 Antibiotic control policy

9.3.1 Antimicrobial Use Committee

The appropriate use of antimicrobial agents is facili-tated through the Antimicrobial Use Committee(3,10). This committee recommends antibiotics for the


60

● notify infection control promptly of any unusualantimicrobial resistance patterns in organisms iso-lated from clinical specimens.

One of the most important functions of the microbi-ology laboratory is to determine the antibioticsusceptibility of organisms isolated from infectedpatients, in order to assist the physician in the choiceof treatment.

9.3.3 Monitoring antimicrobial use

Antimicrobial use in the facility must be monitored.This is usually performed by the pharmacy depart-ment, and should be reported in a timely manner tothe Antimicrobial Use Committee and the MedicalAdvisory Committee. Specific elements to be moni-tored include the amount of different antimicrobialsused during a given period and trends in antimi-crobial use over time. In addition, the antimicrobialuse in specific patient areas such as the intensivecare units or haematology/oncology units shouldbe analysed.

In addition to monitoring antimicrobial use, inter-mittent audits should be undertaken to explore theappropriateness of antimicrobial use. These auditsshould be undertaken under the auspices of theAntimicrobial Use Committee. The antimicrobial useto be audited will be based on changes observed inantimicrobial use, antimicrobial resistance of organ-isms, or concerns about poor patient outcomes. Phy-sicians who are caring for patients must participatein planning the audit and analysis of data. Prior toundertaking the audit a series of appropriate guide-lines for antimicrobial use should be developed andapproved by the medical staff. A chart audit to de-termine to what extent the antimicrobials prescribedmeet these criteria is then performed. If the criteriahave not been met, reasons for inappropriate useshould be identified.

References

1. World Health Organization.WHO Global Strategy forContainment of Antimicrobial Resistance. WHO/CDS/CSR/DRS/2001.2.

2. Struelens MJ. The epidemiology of antimicrobialresistance in hospital-acquired infections: prob-lems and possible solutions. BMJ, 1998, 317:652–654.

3. Shlaes DM et al. Society for Healthcare Epidemi-ology of America and Infectious Diseases Societyof America Joint Committee on the Preventionof Antimicrobial Resistance: Guidelines for theprevention of antimicrobial resistance in hospi-tals. Infect Control Hosp Epidemiol, 1997, 18:275–291.

4. Working Party of the British Society for Antimi-crobial Chemotherapy. Hospital antibiotic con-trol measures in the UK. J Antimicrob Chemother,1994, 34:21–42.

5. Swedish-Norwegian Consensus Group. Antibioticprophylaxis in surgery: Summary of a Swedish-Norwegian consensus conference. Scand J Infect Dis,1998, 30:547–557.

6. Dellinger EP et al. Quality standard for antimi-crobial prophylaxis in surgical procedures. ClinInfect Dis 1994, 18:422–427.

7. Martin C, the French Study Group on Antimicro-bial Prophylaxis in Surgery, the French Societyof Anesthesia and Intensive Care. Antimicrobialprophylaxis in surgery: General concepts andclinical guidelines. Infect Control Hosp Epidemiol,1994,15:463–471.

8. Page CP et al. Antimicrobial prophylaxis for sur-gical wounds: Guidelines for clinical care. ArchSurg 1993, 128:79–88.

9. Ayliffe GAJ. Recommendations for the control of methi-cillin-resistant Staphylococcus aureus (MRSA).WHO/EMC/LTS/96.1.

10. Weekes LM, Brooks C. Drugs and therapeuticcommittees in Australia: Expected and actual per-formance. Brit J Clin Pharmacol, 1996, 42:551–557.

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CHAPTER X

Preventing infections of staff

Factors associated with an increased likelihood ofoccupational acquisition of HIV infection followinginjury include:

● deep (intramuscular) injury

● visible blood on the injuring device

● injuring device used to enter a blood vessel

● source patient with high viral load

● hollow-bore needle

Information on preventive measures must be pro-vided to all staff with potential exposure to bloodand blood products. Policies must include screeningof patients, disposal of sharps and wastes, protectiveclothing, managing inoculation accidents, steriliza-tion and disinfection.

Hospital policy must include measures to promptlyobtain serological testing of source patients wherenecessary. Postexposure prophylaxis should bestarted within four hours of exposure. The use ofpostexposure antiretroviral drugs is recommended.The combination of antiretroviral drugs, zidovudine(AZT), lamivudine (3TC), and indinavir is currentlyrecommended, but local or national guidelinesshould be followed, if available.

A blood sample must be obtained for HIV testingfrom the health care worker as soon as possibleafter exposure, and at regular intervals to documenta possible seroconversion. Health care workers mustbe informed of the clinical presentation of the acuteretroviral syndrome, resembling acute mononucle-osis, which occurs in 70% to 90% of patients withacute HIV infection, and immediately report any ill-ness occurring within 3 months of injury.

An occupational exposure can occur at any time:counselling, testing and treatment must therefore beavailable 24 hours a day. Follow-up of an HIV expo-sure must be standardized, with repeated serologi-cal investigations for up to one year.

Health care workers are at risk of acquiringinfection through occupational exposure (1).

Hospital employees can also transmit infections topatients and other employees. Thus, a programmemust be in place to prevent and manage infectionsin hospital staff.

Employees’ health should be reviewed at recruit-ment, including immunization history and previ-ous exposures to communicable diseases (e.g.tuberculosis) and immune status. Some previousinfections (e.g. varicella-zoster virus [VZV]) may beassessed by serological tests.

Immunizations recommended for staff include: hepa-titis A and B, yearly influenza, measles, mumps,rubella, tetanus, diphtheria. Immunization againstvaricella may be considered in specific cases. TheMantoux skin test will document a previous tuber-culosis infection and must be obtained as a base-line.

Specific postexposure policies must be developed,and compliance ensured for: human immunodefi-ciency virus (HIV), hepatitis A virus, hepatitis B virus,hepatitis C virus, Neisseria meningitidis, Mycobacteriumtuberculosis, varicella-zoster virus, hepatitis E virus,Corynebacterium diphtheriae, Bordetella pertussis, and rabies.

10.1 Exposure to human immunodeficiencyvirus (HIV) (2,3,4)

The probability of HIV infection following needlestickinjury from an HIV-positive patient is 0.2% to 0.4%per injury (1). Risk reduction must be undertakenfor all bloodborne pathogens, including:

● adherence to standard (routine) precautions withadditional barrier protection as appropriate

● use of safety devices and a needle disposal sys-tem to limit sharps exposure

● continuing training for health care workers in safesharps practice.


62

10.2 Exposure to hepatitis B virus (3,4,5)

Estimates of the probability of HBV infection byneedlestick injury range from 1.9% to 40% per in-jury. With a sharps injury, the source person mustbe tested at the time of exposure to determinewhether he or she is infected. Infection of the healthcare worker can occur when detection of hepatitis Bsurface antigen (HBsAg) or e antigen (HBeAg) is posi-tive in the source person.

For previously immunized individuals with an anti-HBs antibody greater than 10 mlU/ml, no furthertreatment is required. For others, prophylaxis con-sists of the intramuscular injection of hepatitis Bimmune globulin, and a complete course of hepati-tis B vaccine. Hepatitis B immunoglobulin must begiven as soon as possible, preferably within 48 hours,and not later than a week after exposure. Post-immunization serology should be obtained to dem-onstrate an adequate serological response.

Delta hepatitis occurs only in individuals with hepa-titis B virus infection, and is transmitted by similarroutes. Preventive measures against hepatitis B arealso effective for the delta agent.

10.3 Exposure to hepatitis C virus (5)

The routes of infection are similar to hepatitis B in-fection. No postexposure therapy is available forhepatitis C, but seroconversion (if any) must be docu-mented. As for hepatitis B viral infection, the sourceperson must be tested for HCV infection.

For any occupational exposure to bloodborne patho-gens, counselling and appropriate clinical and sero-logical follow-up must be provided.

10.4 Neisseria meningitidis infection

N. meningitidis can be transmitted through respira-tory secretions. Occupational infections are rare, butthe severity of the disease warrants appropriate che-moprophylaxis for close contact between patientsand health care workers. Close contact is defined asdirect mouth-to-mouth contact as in resuscitationattempts. Recommended prophylaxis includes oneof: rifampin (600 mg twice a day for two days), asingle dose of ciprofloxacin (500 mg), or a single doseof ceftriaxone (250 mg) IM.

10.5 Mycobacterium tuberculosis (6)

Transmission to hospital staff occurs through air-borne droplet nuclei, usually from patients withpulmonary tuberculosis. The association of tuber-culosis with HIV infection and multidrug-resistanttuberculosis are a current major concern. In the caseof health care exposure, individuals with Mantouxconversion (≥10 mm induration) following exposureshould be considered for isoniazid prophylaxis, de-pending on local recommendations.

10.6 Other infections (varicella, hepatitis Aand E, influenza, pertussis, diphtheriaand rabies) (1)

Transmission of these microorganisms may be un-common, but policies to manage staff exposureshould be developed. Vaccination of hospital staffagainst varicella and hepatitis A is recommended.Influenza vaccination should be given yearly. Ra-bies vaccination may be appropriate in some facili-ties in countries where rabies is endemic.

References

1. CDC guidelines for infection control in hospitalpersonnel. Am J Infect Control, 1998, 26:289–354 orInfect Control Hosp Epidemiol 1996; 17:438–473.

2. Bouvet E. Risk for health professionals of infec-tion with human immunodeficiency virus.Current knowledge and developments in preven-tive measures. Médecine et Maladies Infectieuses, 1993,23:28–33.

3. Health Canada. An integrated protocol to man-age health care workers exposed to bloodbornepathogens. Can Commun Dis Rep, 1997, 23 Suppl 2:i–iii, 1–14; i–iii, 1–16.

4. Health Canada. Preventing the transmission ofbloodborne pathogens in health care and publicservices. Can Commun Dis Rep, 1997, 23 Suppl 3:i–vii, 1–43; i–vii, 1–52.

5. AIDS/TB Committee of the Society of Health CareEpidemiology of America. Management of healthcare workers infected with hepatitis B virus, hepa-titis C virus, human immunodeficiency virus orother bloodborne pathogens. Infect Control HospEpidemiol, 1997, 18:347–363.

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ANNEX 1

Suggested further reading

Basic food safety for health workers, Adams M, MotarjemiM. WHO/SDE/PHE/FOS/99.1. Order No. 1930166.

Safe management of wastes from health-care activities, ed-ited by Prüss A, Giroult E, Rushbrook P, 1999. ISBN92 4 15425 9, Order No. 1150453.

Best infection control practices for skin-piercing intradermal,subcutaneous, and intramuscular needle injection. 2001,WHO/BCT/DCT/01.02.

Others

Abrutyn E, Goldmann D, Scheckler W, eds. Saundersinfection control reference service (2nd ed). Philadel-phia, Saunders, 2001.

Bennett JV and Brachman PS, eds. Hospital infections(4th ed). Philadelphia, Lippincott-Raven, 1998.

Damani NN. Manual of infection control procedures. Lon-don, Greenwich Medical Media, 1997.

Glynn A et al. Hospital-acquired infection: Surveillance,policies and practice. London, Public Health Labora-tory Service, 1997.

Herwaldt LA, Decker MD, eds. A practical handbook forhospital epidemiologists. Society for Healthcare Epi-demiology of America (SHEA), 1998.

Lynch P et al. Infection prevention with limited resources (Ahandbook for infection committees). Chicago, ETNACommunications, 1997.

Mayhall C Glen, ed. Hospital epidemiology and infectioncontrol (2nd ed). Philadelphia, Lippincott, Williams& Wilkins, 1999.

Wenzel RP, ed. Prevention and control of hospital infections(3rd ed). Philadelphia, Lippincott, Williams &Wilkins, 1997.

World Health Organization

Indoor air quality: Biological contaminants. EuropeanSeries No. 31, 1990. ISBN 92 890 1122 X, OrderNo. 1310031.

Hazard Analysis Critical Control Point Evaluation. A guideto identifying hazards and assessing risks associated withfood preparation and storage, Bryan FL, 1992. ISBN92 4 154433 3, Order No. 1150370.

The hospital in rural and urban districts. Report of a WHOStudy Group on the functions of hospitals at the first re-ferral level. WHO Technical Report Series, No. 819,1992. ISBN 92 4 120819 8, Order No. 1100819.

Basic epidemiology, Beaglehole R, Bonita R, KjellströmT, 1993. ISBN 92 4 154446 5, Order No. 1150395.

Guidelines for drinking-water quality, Vol. 1, Recommenda-tions, 2nd edition. WHO, Geneva, 1993.

Guidelines for antimicrobial resistance surveillance. WHORegional Publications, Eastern MediterraneanSeries No. 15, 1996. ISBN 92 9021 213 6, OrderNo. 14400 15.

Food safety and foodborne disease, World Health Sta-tistics Quarterly, Vol. 50, No. 1/2, 1997. Order No.0085012.

Assessment of exposure to indoor air pollutants, edited byJantunen M, Jaakkola JJK and Krzyzanowski M.European Series No. 78, 1997. ISBN 92 890 1342 7,Order No. 1310078.

Sanitation promotion. WSSCC Working Group on Promotionof Sanitation, edited by Simpson-Hébert M, WoodS. WHO/EOS/98.5. Order No. 1930147.

Infection control for viral haemorrhagic fevers in the Africanhealth care setting. WHO/EMC/ESR/98.2.

ANNEX 2

Internet resources

AIRHH: International Association for Research in Hospital Hygiene (Monaco)http://www.monaco.mc/assoc/airhh/

APIC: Association for Professionals in Infection Control and Epidemiology (USA)http://www.apic.org/

APSI: Associazione Controllo Infezioni (Italy)http://www.apsi.it

CDC: Centers for Disease Control and Prevention (USA)http://www.cdc.gov/cdc.htm

Health Canada: Division of Nosocomial and Occupational Infectionshttp://www.hc-sc.gc.ca/hpb/lcdc/bid/nosocom/index.html

HELICS: Hospital in Europe Link for Infection Control through Surveillancehttp://helics.univ-lyon1.fr

Hospital Infection Society (UK)http://www.his.org.uk/

Infection Control Nurses Association (UK)http://www.icna.co.uk

IFIC: International Federation of Infection Controlhttp://www.ific.narod.ru/

NNIS: National Nosocomial Infections Surveillance System (USA)http://www.cdc.gov/ncidod/hip/nnis/@nnis.htm

SFHH: Société Française d’Hygiène Hospitalière (France)http://sfhh.univ-lyon1.fr/

SHEA: Society for Healthcare Epidemiology of America (USA)http://www.shea-online.org

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