Line associated infections and bacteraemia

Dr. Brian O’Connell

Adapted from Bone et al. Chest 1992; 101: 1644-55

Gram negative cell wall

Diagram of a Gram-positive bacterial cell-wall

Microbial triggers of sepsis

• Bacteraemia/fungaemia– Positive blood cultures are more common the more severe

the disease• More likely to have positive blood cultures in patients with septic

shock• Severe local infections associated with greater mortality

• Endotoxaemia – lipopolysaccharide

• Other bacterial toxins– Bacterial superantigens (e.g. TSST-1, streptococcal

pyrogenic exotoxins)

Diagnosis of Sepsis

• No bedside or laboratory test provides a definitive diagnosis

• Clinical evidence of SIRS (tachycardia, tachypnea, leucocytosis, fever) with altered mental status, hyperbilirubinaemia, acidosis, thrombocytopenia

• Non-infective causes include:– Burns, pancreatitis, trauma, adrenal insufficiency, malignant

hyperthermia, heat-stroke, hypersensitivity reactions)

Identifying Acute Organ Dysfunction as a Marker of Severe Sepsis

TachycardiaHypotension

CVP PAOP

Jaundice Enzymes Albumin

PT

Altered Consciousness

ConfusionPsychosis

TachypneaPaO2 <70 mm Hg

SaO2 <90%PaO2/FiO2 300

OliguriaAnuria

Creatinine

Platelets PT/APTT Protein C D-dimer

Bacteraemia/Blood-stream Infection (BSI)

• Primary • cause majority of hospital-acquired BSI (64%)• most are due to infected intravascular catheters• remainder have bacteraemia with no identifiable source

• Secondary • Secondary infections are related to severe infections at

other sites, such as the urinary tract, lung, postoperative wounds, and skin.

• Cause the majority of community-acquired BSI

Patterns of bacteraemia3 patterns of bacteraemia

1. Transient– Lasts minutes to hours– Instrumentation of contaminated mucosal surface

• Tooth brushing, dental procedures, cystoscopy– manipulation of infected tissue

2. Intermittent• Usually from un-drained infection

3. Continuous– Usually from an endovascular infection

• Endocarditis, infected aneurysm,

Diagnosis of bacteraemia

• Blood culture– Take two sets from different sites

• Should be performed on all hospitalised patients with fever (≥38ºC) combined with leucocytosis or leucopaenia before the use of parenteral or systemic antimicrobial therapy

• Systemic and localized infections including suspected acute sepsis, meningitis, osteomyelitis, arthritis, acute untreated bacterial pneumonia, or fever of unknown origin in which abscess or other bacterial infection is suspected or possible

Taking a blood culture from a central line

Taking a blood culture from a Peripheral vein

Blood cultures

Take at least 10 ml per set

• What are the most common organisms recovered from blood?

Different groups of patients

Traditional divisions : 2 broad groups

hospital acquired

community acquired

New divisions: 3 groups

Hospital acquired

Health-care association

Non health-care association / Unknown

DefinitionsHospital acquired (HA):

isolate recovered from inpatient > 48 h in hospital

Health care associated (HCA):

isolate recovered from patient with one of the following risk factors

• inpatient in SJH in previous 90 days

• outpatient in SJH in previous 30 days

• referred or transferred from another hospital

• resident in nursing home

Non Hospital or Healthcare associated (NHCA):

isolate from patient not defined as HA or HCA

Top 5 Bacteraemia isolates in SJH during 2006

HA

n = 658CNS 315 (48%)

S. aureus 78 (12%)

E. coli 60 (9%)

E. faecium 30 (5%)

E. faecalis 22 (3%)

HCA

n = 279CNS 122 (44%)

E. coli 35 (13%)

S. aureus 24 (9%)

S. pneumoniae 17 (6%)

S. maltophilia 7 (3%)

NHCA

n = 274CNS 142 (52%)

E. coli 39 (14%)

S. aureus 1 8 (7%)

S. pneumoniae 11 (4%)

BHS Gp.A 7 (3%)

Micro-organisms causing bacteraemia

• Overall change from predominantly Gram-negative infection to Gram-positive infection

Single organism bacteraemias in EORTC trials of febrile neutropenia

02468101214161820

I(1973-

78)

II(1978-

80)

III(1980-

83)

IV(1983-

86)

V(1986-

88)

VIII(1988-

90)

IX(1991-

92)

X(1993-

94)

XIV(1997-

00)

EORTC Trials

%

Gram (-)

Gram (+)

What are the common sources of blood-stream infection?

• Hospital-acquired– Central line– Urinary tract– Intra-abdominal

• Community-acquired– Urinary tract – Intra-abdominal– Respiratory tract

Management1. Antimicrobial therapy

– Early appropriate antimicrobial therapy improves survival2. Surgical drainage

– Important to look for and drain sources of infection3. IV- fluids, blood transfusion, pressors4. Nutrition5. Other possible therapies

– Steroids– vasopressin– Anti-inflammatory drugs– Anticoagulants

Empiric antimicrobial therapy

• choice depends upon institutional spectrum of infections, susceptibility pattern of infecting micro-organisms and individual clinical situation

Catheter-related infections

• Intravascular catheters are indispensable in modern-day medical practice

• Infections associated with intravascular catheters are a major cause of morbidity & mortality

Infectious complications of central venous catheters (CVCs)

• Local site infection• Catheter-related blood stream infection (CRBSI)• Septic thrombophlebitis

– Endocarditis– Metastatic infection – e.g. endocarditis, lung abscess, brain

abscess, osteomyelitis & endopthalmitis

Appearance of a central venous catheter associated with bacteraemia. Note the minimal surrounding erythema and purulence at the insertion site

Incidence of catheter-related infection varies:-

• Type of catheter - non-tunnelled vs. tunnelled

• Site of catheter – int. jugular > subclavian

• Number of catheter days

• Frequency of catheter manipulation

• Setting of catheter placement i.e. emergency/elective

Incidence of catheter-related infection varies:

• Hospital size

• Hospital service/unit

• Patient-related factors e.g. underlying disease and acuity of illness

Pathogenesis of catheter-related blood-stream infection

Scanning electron micrograph of a Staphylococcus biofilm.Emerging Infectious Diseases 2001; 7: 277-281

Epidemiology

• In the U.S., 15 million catheter days occur in ICUs each year

• Average rate of catheter associated bacteraemias is 5.2 per 1,000 catheter days

• So, approximately 78,000 catheter associated infections occur in ICUs in the US each year

• 250,000 cases annually if entire hospitals assessed rather than exclusively ICUs

Consequences

• Significant increase in patient morbidity & mortality

• Significant increase in hospital costs

• Significant increase in duration of hospitalisation

Morbidity & Mortality

Meta-analysis of 2573 CRBSIs

• Case fatality rate – 14%

• Directly attributable to CVC – 19%

• Mortality rate highest for S. aureus bacteraemia – 8.2% overall

Cost

• In ICU studies, cost per infection is an estimated $34,500 - $56,000

• Annual cost of caring for patients with CRBSIs estimated at up to $2.3 billion

Common pathogens isolated in CRBSIs

Pathogen 1986 – 1989 (%) 1992 – 1999 (%)

Coagulase negative Staphylococci

27 37

Staphylococcus aureus 1613

(>50% MRSA isolated)

Enterococcus spp.8

(0.5% VRE)

13

(25.9% VRE)

Gram-negative rods

E.coli

Enterobacteraciae

P. aeruginosa

K. pneumoniae

19

6

5

4

4

14

2

5

4

3

Candida spp. 8 8

Catheter-Related Blood stream infection (CRBSI)

DefinitionEssential Criteria: Peripheral blood culture positive

Clinical signs and symptoms of infection

(Temp>=38ºC or rigors/chills or hypotension)

No other obvious source of sepsis

And one of the following:

1. 15 CFU on line tip

2. > 2 h differential time to positivity

(Central vs. Peripheral)Guidelines for prevention of Intra-vascular Catheter Related infections

MMWR August 9,2002/Vol.51/No.RR-10

Tunnelled CVC-related blood stream infection

Complicated infection

Tunnel infection or port abscess

Septic thrombosis, endocarditis, osteomyelitis

Remove CVC/ID & treat with antibiotics for10–14 days

Remove CVC/ID & treat with antibiotics for 4 – 6 weeks, 6 – 8 weeks for osteomyelitis

Management of Catheter-related blood-stream infection

Tunnelled CVC-related blood stream infection

Uncomplicated infection

Coagulase negative Staphylococcus

S. aureus

•May retain CVC & use systemic antibiotic for 7 days plus antibiotic lock therapy for 10 – 14 days

•Remove CVC if there is clinical deterioration or persisting or relapsing bacteraemia

•Remove CVC & use systemic antibiotic for 14 days if TOE –ve

•For CVC salvage, if TOE –ve use systemic & antibiotic lock therapy for 14 days

•Remove CVC if there is clinical deterioration, persisting or relapsing bacteraemia

Tunnelled CVC-related blood stream infection

Uncomplicated infection

Gram-negative bacilli Candida spp.

•Remove CCV & treat from 10 –14 days

•For CVC salvage use systemic & antimicrobial lock therapy for 14 days

•If no response, remove CVC & treat with systemic antibiotics for 10 – 14 days

•Remove CVC & treat with antifungal therapy for 14 days after last positive culture

Strategies for prevention

Quality assurance and continuing education• Standardisation of aseptic care• Staff training in CVC insertion & maintenance• Specialised “IV teams”• Appropriate staffing levels

Audit:• site of catheter insertion• choice of catheter material• hand hygiene• aseptic technique• catheter site dressing regimens