What are the diagnostic criteria and treatment for Central Line-Associated Bloodstream Infection (CLABSI)?

Diagnosis and Treatment of Central Line-Associated Bloodstream Infection (CLABSI)

The definitive diagnosis of CLABSI requires either growth of the same organism from both a peripheral blood culture and catheter tip culture, or growth of the same organism from both catheter-drawn and peripheral blood cultures with specific quantitative differences or time to positivity differences. 1

Diagnostic Criteria for CLABSI

Definition

• CLABSI is defined as a primary bloodstream infection in a patient who had a central venous catheter (CVC) within 48 hours before the development of the infection, not related to infection at another site 2, 3
• When the interval between infection onset and device use is >48 hours, there must be compelling evidence linking the infection to the central catheter 2

Definitive Diagnostic Methods

• Catheter tip culture with peripheral blood culture: Growth of the same organism from at least one peripheral blood culture and from the catheter tip culture 1
• Paired blood cultures with quantitative analysis: Growth of the same organism from catheter-drawn and peripheral blood samples with colony count from catheter hub at least 3-fold greater than from peripheral vein 1
• Differential time to positivity (DTP): Growth of the same organism from catheter-drawn blood at least 2 hours before growth is detected in peripheral blood sample 1
• Alternative for multi-lumen catheters: Two quantitative blood cultures from different catheter lumens with one lumen showing a colony count at least 3-fold greater than the other 1

Blood Culture Collection Technique

• Obtain blood cultures before initiating antimicrobial therapy 1
• Draw paired blood samples from the catheter and a peripheral vein 1
• If peripheral blood sample cannot be obtained, draw ≥2 blood samples through different catheter lumens 1
• Properly disinfect catheter hub with alcohol, alcoholic chlorhexidine (>0.5%), or tincture of iodine 1
• Clearly mark blood culture bottles to indicate the source (catheter vs. peripheral) 1

Catheter Culture Methods

• Catheter cultures should only be performed when CLABSI is suspected, not routinely 1
• For short-term catheters, the roll plate technique (semi-quantitative) is recommended 1
• Growth of >15 CFU from a 5-cm segment of catheter tip by semi-quantitative culture or >10² CFU by quantitative culture indicates catheter colonization 1
• For suspected pulmonary artery catheter infection, culture the introducer tip 1

Treatment of CLABSI

Empiric Antimicrobial Therapy

• Start empiric therapy after obtaining blood cultures when CLABSI is suspected 1
• Use vancomycin for empiric coverage of gram-positive organisms in settings with elevated MRSA prevalence 1
• For institutions where MRSA isolates have vancomycin MIC values >2 μg/mL, consider alternative agents such as daptomycin 1
• Include gram-negative coverage based on local susceptibility patterns (e.g., fourth-generation cephalosporin, carbapenem, or β-lactam/β-lactamase combination) 1
• For neutropenic patients, severely ill patients with sepsis, or patients colonized with MDR gram-negative bacilli, use empiric combination therapy 1
• For femoral catheters in critically ill patients, include coverage for gram-negative bacilli and Candida species 1

Catheter Management

• Remove non-tunneled CVCs in cases of:
  • Evident local infection at exit site 1
  • Clinical signs of sepsis 1
  • Positive culture of catheter exchanged over guidewire 1
  • Positive paired blood cultures 1
• Long-term catheters should be removed with:
  • Severe sepsis 1
  • Suppurative thrombophlebitis 1
  • Endocarditis 1
  • Persistent bloodstream infection despite appropriate antimicrobial therapy 1

Duration of Antimicrobial Therapy

• Day 1 of therapy is considered the first day on which negative blood culture results are obtained 1
• For uncomplicated CLABSI with catheter removal: 10-14 days of antimicrobial therapy 1
• For persistent bacteremia or fungemia (>72h after catheter removal): 4-6 weeks of therapy 1
• For patients with infective endocarditis or suppurative thrombophlebitis: 4-6 weeks 1
• For osteomyelitis: 6-8 weeks in adults; 4-6 weeks in pediatric patients 1

Risk Factors and Prevention

Risk Factors for CLABSI

• Duration of catheterization (>1 week significantly increases risk) 2, 4
• Catheter site (femoral and jugular sites have higher infection rates than subclavian) 2, 4
• Use of catheter for parenteral nutrition 2, 4
• Multilumen catheters 3
• Use of more than one central venous catheter 3
• Hematologic malignancy 4, 3
• Prolonged ICU stay 3

Prevention Strategies

• Select optimal insertion site (subclavian preferred over jugular or femoral) 4
• Use maximal sterile barrier precautions during insertion 4
• Implement proper hand hygiene 4
• Use >0.5% chlorhexidine with alcohol for skin antisepsis 4
• Apply sterile, transparent dressings and change according to protocol 1
• Choose catheters with minimum number of lumens necessary 4
• Consider antimicrobial-impregnated catheters for high-risk patients 4
• Maintain adequate nurse-to-patient ratio in ICUs 1
• Apply chlorhexidine-containing dressings for patients over two months of age 1

Common Pitfalls and Caveats

• Avoid diagnosing CLABSI based solely on clinical symptoms without microbiological confirmation 1
• Do not draw blood cultures only from the catheter, as this increases the risk of false-positive results 1
• Avoid routine catheter tip cultures when CLABSI is not suspected 1
• Do not use qualitative broth culture of catheter tips as it has poor specificity 1
• Avoid routine prophylactic antibiotics before or during CVC use 1
• Do not use linezolid for empirical therapy in patients suspected but not proven to have bacteremia 1
• Remember that DTP may not discriminate between CLABSI and non-CLABSI for patients already receiving antibiotics 1