Part 3: Supplemental Prevention Strategies, Diagnosis & Management of CRBSI

1. Supplemental Prevention Strategies

The following strategies are recommended as supplemental approaches — to be considered when CLABSI rates remain elevated despite full implementation of and high compliance with the standard insertion and maintenance bundles, or in specific high-risk patient populations.¹²

1.1 Antimicrobial-Impregnated Catheters

Antimicrobial-impregnated or -coated central venous catheters deliver antimicrobial agents at the catheter surface to inhibit microbial adhesion and biofilm formation. Two primary types have been extensively studied:³⁴

1.1.1 Chlorhexidine–Silver Sulfadiazine (CHG-SS) Catheters

Description: First-generation CHG-SS catheters coat only the external surface; second-generation catheters coat both internal and external surfaces with higher concentrations of chlorhexidine and silver sulfadiazine.

Evidence:

• First-generation (external only) CHG-SS catheters reduce catheter colonization and CLABSI in patients with catheters in place for <7–10 days (meta-analysis: relative risk of CLABSI approximately 0.44)³
• Second-generation (internal + external) catheters provide more sustained activity and are effective for longer catheter dwell times⁴
• CHG-SS catheters are less effective than minocycline-rifampin catheters in head-to-head comparative trials⁵

1.1.2 Minocycline-Rifampin (M-R) Catheters

Description: Both the internal and external surfaces of the catheter are impregnated with minocycline and rifampin.

Evidence:

• A randomized controlled trial directly comparing M-R catheters with first-generation CHG-SS catheters demonstrated a threefold reduction in catheter colonization and CLABSI with M-R catheters⁵
• Meta-analytic data confirm that M-R catheters reduce CLABSI by approximately 55–70% compared with standard noncoated catheters⁴
• Concern about promoting rifampin resistance has not been substantiated in clinical studies, though monitoring is warranted
• M-R catheters are more expensive than standard catheters but are cost-effective when baseline CLABSI rates exceed approximately 2 per 1,000 catheter-days¹

1.1.3 When to Use Antimicrobial-Impregnated Catheters

1.2 Antimicrobial Lock Therapy for Prevention (Prophylactic Lock Solutions)

Antimicrobial lock therapy involves instilling a concentrated antimicrobial solution into the catheter lumen during periods of non-use (dwell time typically 8–24 hours) to prevent intraluminal biofilm formation and CLABSI.¹⁶

1.2.1 Agents for Prophylactic Antimicrobial Lock

1.2.2 Indications for Prophylactic Lock Therapy

• Patients with long-term central venous catheters (tunneled catheters, implanted ports) who have experienced recurrent CLABSI despite optimal catheter care
• Hemodialysis catheter-dependent patients with high CLABSI rates despite adherence to dialysis catheter care guidelines
• Patients with limited remaining vascular access sites in whom catheter preservation is critical
• Not recommended as a routine measure for all short-term ICU central venous catheters¹²

1.3 CHG-Impregnated Sponge Dressings

As discussed in Part 2, chlorhexidine-impregnated sponge or gel pad dressings placed at the catheter insertion site provide continuous local antisepsis and have been shown in randomized trials to reduce catheter colonization and CRBSI by 50–65%.⁷⁸

Recommendation: Use CHG-impregnated dressings for central venous catheters in patients older than 2 months of age, particularly when CLABSI rates are not decreasing despite implementation of the basic bundle, or in units with high baseline CLABSI rates.¹²

1.4 Antibiotic Ointments at the Insertion Site

Recommendation: Apply povidone-iodine antiseptic ointment or bacitracin/gramicidin/polymyxin B ointment to the hemodialysis catheter exit site at the time of catheter insertion and at each dressing change, unless the ointment is incompatible with the catheter material (manufacturer recommendations should be checked). Do not use antibiotic ointments at non-hemodialysis central line insertion sites, as they may promote fungal infections and antimicrobial resistance.³

2. Diagnosis of Catheter-Related Bloodstream Infection (CRBSI)

2.1 When to Suspect CRBSI

CRBSI should be suspected in any patient with a central venous catheter who develops:

• Fever (temperature ≥38.3 C) or hypothermia (temperature <36.0 C) without another obvious source
• Chills or rigors, especially occurring within 1–2 hours after catheter manipulation or flushing
• Hemodynamic instability (new hypotension, tachycardia) without other explanation
• Local signs at the catheter insertion site: erythema, tenderness, purulent drainage, induration
• New-onset sepsis or septic shock in a patient with a central line as the most likely source
• Positive blood culture drawn from the catheter or peripherally in a patient with a central line, without an identified alternative source³⁹

Important: Not all CLABSIs are CRBSIs, and not all bloodstream infections in patients with central lines are catheter-related. Clinical judgment combined with microbiologic data is essential to determine whether the catheter is truly the source.

2.2 Diagnostic Methods

2.2.1 Paired Blood Cultures (Peripheral and Catheter-Drawn)

Recommended as the first-line diagnostic approach when CRBSI is suspected and catheter retention is desired.

• Draw at least two sets of blood cultures: one from a peripheral vein (by percutaneous venipuncture) and one from the catheter hub/lumen
• Each set should contain both an aerobic and an anaerobic bottle
• Cultures should be drawn simultaneously (or within a short time window) and before initiation of empiric antibiotics whenever possible
• The samples should be of adequate volume (20 mL per set in adults: 10 mL per bottle)
• Label each culture with the draw site (peripheral vs. catheter lumen, specifying which lumen in multilumen catheters)⁹¹⁰

2.2.2 Differential Time to Positivity (DTP)

This is the most practical method for diagnosing CRBSI without requiring catheter removal.

Important considerations:

• DTP is most reliable when cultures are drawn simultaneously and processed in the same automated blood culture system
• DTP is not valid if the patient has received antibiotics through the catheter before the cultures were drawn (antibiotic activity in the lumen can delay time to positivity)
• DTP applies to short-term nontunneled catheters; its accuracy for long-term tunneled catheters and ports is less well established¹⁰¹¹

2.2.3 Catheter Tip Culture (Post-Removal)

Performed when the catheter has been removed and CRBSI is suspected.

CRBSI is diagnosed when:

• The same organism is isolated from both the catheter tip (by semi-quantitative or quantitative culture meeting the threshold) and a peripheral blood culture
• No other source of infection is identified

Important notes on catheter tip culture:

• The catheter tip should be sent for culture only when CRBSI is clinically suspected — do not routinely culture catheter tips upon removal, as this leads to unnecessary antibiotic use and does not improve outcomes
• The catheter tip should be cut with sterile scissors and transported in a sterile, dry container (not in liquid broth, which may yield false-positive results)
• Do not culture the catheter tip after applying antiseptic to the external surface, as this may yield false-negative results³¹²

2.2.4 Quantitative Catheter-Drawn Blood Cultures

When paired with peripheral quantitative cultures, a catheter-to-peripheral colony count ratio of ≥3:1 (or ≥5:1 by some criteria) supports the diagnosis of CRBSI. This method requires quantitative blood culture capability, which is not available in all clinical microbiology laboratories.¹⁰

2.3 Diagnostic Algorithm

Patient with central line + suspected bloodstream infection
    │
    ├── Can catheter be removed?
    │       │
    │       ├── YES → Remove catheter → Send catheter tip for
    │       │          semi-quantitative or quantitative culture
    │       │          + Draw 2 sets of peripheral blood cultures
    │       │          → CRBSI confirmed if same organism from
    │       │             catheter tip (≥15 CFU) AND peripheral blood
    │       │
    │       └── NO (catheter salvage desired)
    │               │
    │               └── Draw PAIRED blood cultures simultaneously:
    │                   1 set from catheter, 1 set from peripheral vein
    │                   → Assess differential time to positivity (DTP)
    │                   → CRBSI supported if catheter-drawn culture
    │                      positive ≥2 hours before peripheral culture
    │
    └── Start empiric antibiotics after cultures drawn
        (do NOT delay therapy for diagnostic workup)

3. Management of Catheter-Related Bloodstream Infection

3.1 General Principles

1. Obtain blood cultures (paired peripheral and catheter-drawn) before initiating empiric antibiotics
2. Start empiric antimicrobial therapy promptly in patients with suspected CRBSI who are hemodynamically unstable, septic, or critically ill — do not withhold antibiotics pending culture results
3. Assess the need for catheter removal based on the clinical scenario, causative organism, catheter type, and patient factors
4. Narrow antimicrobial therapy once culture and susceptibility results are available (de-escalation)
5. Determine duration of therapy based on the organism, whether the catheter is removed or retained, and the presence or absence of complications⁹¹³

3.2 Empiric Antimicrobial Therapy

Recommendation: Empiric therapy for suspected CRBSI should cover the most likely pathogens based on the patient’s risk factors, catheter type, and local antibiogram.⁹¹³

Vancomycin Dosing:

• Loading dose: 25–30 mg/kg actual body weight IV
• Maintenance: target AUC/MIC 400–600 (guided by Bayesian vancomycin monitoring software when available); traditional trough-based monitoring targets of 15–20 mcg/mL have been superseded by AUC-guided dosing¹⁴

Daptomycin (6–10 mg/kg IV once daily) is an alternative to vancomycin for gram-positive coverage, particularly in patients with vancomycin-resistant organisms, documented vancomycin allergy, or persistent MRSA bacteremia not responding to vancomycin.⁹¹³

3.3 Catheter Removal vs. Salvage

The decision to remove or attempt to salvage the catheter depends on the causative organism, catheter type, clinical severity, and availability of alternative vascular access.⁹¹³

3.3.1 Indications for Catheter Removal

3.3.2 Catheter Salvage

Catheter salvage (retaining the catheter and treating with systemic antibiotics ± antibiotic lock therapy) may be considered in limited circumstances:⁹¹³

Salvage protocol:

1. Systemic antibiotics targeted to the organism (see duration tables below)
2. Antibiotic lock therapy instilled into the catheter lumen (dwell 8–24 hours per day) for the duration of systemic therapy
3. Repeat blood cultures at 48–72 hours to confirm clearance
4. If cultures remain positive at 72 hours, remove the catheter
5. Monitor for relapse after completion of therapy

3.3.3 Antibiotic Lock Therapy for Catheter Salvage

Lock technique:

• Fill the catheter lumen with the antibiotic lock solution (typical volume 2–5 mL depending on catheter lumen volume)
• Allow the solution to dwell for 8–24 hours (usually overnight or between uses)
• Aspirate and discard the lock solution before each catheter use
• Reinstill fresh lock solution after each use
• Continue for the duration of systemic antibiotic therapy (typically 7–14 days)⁹¹⁵

3.4 Duration of Antimicrobial Therapy by Organism

Duration depends on the organism, whether the catheter is removed, and whether complications are present.⁹¹³

3.5 Special Considerations by Organism

3.5.1 Staphylococcus aureus CRBSI

S. aureus bacteremia from any source — including CRBSI — warrants particularly rigorous management due to the high rate of metastatic complications (endocarditis, osteomyelitis, septic emboli).¹³¹⁶

Mandatory workup and management steps:

1. Remove the catheter — salvage is not recommended for S. aureus CRBSI
2. Obtain repeat blood cultures every 24–48 hours until clearance is documented
3. Obtain transesophageal echocardiography (TEE) to evaluate for endocarditis — transthoracic echocardiography (TTE) has insufficient sensitivity to exclude vegetations; TEE is recommended for all cases of S. aureus bacteremia unless comorbidities preclude the procedure
4. Minimum 14 days of IV antibiotics from the first negative blood culture date if TEE is negative, there is no prosthetic material, and bacteremia clears within 72 hours of catheter removal
5. 4–6 weeks of IV antibiotics if TEE shows vegetations, if prosthetic material is present, or if bacteremia persists >72 hours after catheter removal
6. Infectious disease consultation is recommended for all cases of S. aureus bacteremia — studies demonstrate reduced mortality and relapse rates with ID consultation¹⁶

3.5.2 Candida CRBSI

1. Remove the catheter — this is mandatory for all Candida bloodstream infections associated with a central line
2. Empiric antifungal therapy: Echinocandin (micafungin 100 mg IV daily, caspofungin 70 mg IV load then 50 mg daily, or anidulafungin 200 mg IV load then 100 mg daily) is the preferred first-line agent. Fluconazole 800 mg load then 400 mg daily is acceptable if the patient is hemodynamically stable, not neutropenic, and has no recent azole exposure
3. Duration: 14 days from the first negative blood culture after catheter removal
4. Ophthalmologic evaluation for Candida endophthalmitis in all patients with candidemia (within 1 week of diagnosis in non-neutropenic patients; after neutrophil recovery in neutropenic patients)
5. Speciate the Candida isolate and obtain antifungal susceptibility testing; adjust therapy based on species and susceptibility (C. glabrata and C. krusei may be fluconazole-resistant; C. auris may be multidrug-resistant)¹³¹⁷

3.5.3 Persistent Bacteremia / Fungemia

If blood cultures remain positive after 72 hours of appropriate antimicrobial therapy and catheter removal, evaluate for:

• Metastatic infection: Endocarditis (TEE), osteomyelitis (MRI), septic thrombophlebitis (CT with contrast or duplex ultrasound), epidural abscess, septic arthritis, septic pulmonary emboli
• Retained infected foreign body (e.g., another intravascular device, prosthetic valve, prosthetic joint)
• Antimicrobial resistance — review susceptibility data; consider broadening therapy
• Inadequate source control — consider repeat imaging for undrained collections

3.6 Suppurative Thrombophlebitis

Suppurative (septic) thrombophlebitis involves infection of a thrombus within the catheterized vein, creating a continuous source of bacteremia or fungemia. It should be suspected when:⁹¹³

• Bloodstream infection persists despite catheter removal and appropriate antimicrobial therapy
• There is clinical evidence of venous thrombosis (edema, erythema along the vessel course, palpable cord)
• Imaging (CT with contrast, Doppler ultrasound) demonstrates thrombus in the catheterized vein

Management of Suppurative Thrombophlebitis:

4. Guidewire Exchange

Recommendation: Guidewire exchange of a central venous catheter should not be performed routinely to prevent infection. However, guidewire exchange may be appropriate in the following circumstances:³

• Catheter malfunction (occlusion, malposition) in a patient without evidence of infection at the existing insertion site
• Need for a different catheter type (e.g., exchange to a larger-bore or multilumen catheter) when the existing site is preferred

Contraindications to guidewire exchange:

• Documented or suspected catheter-related infection at the existing site
• Purulence or cellulitis at the insertion site
• Known bacteremia/fungemia

If guidewire exchange is performed:

• Full maximal sterile barrier precautions must be used (as for new insertion)
• The removed catheter tip should be sent for semi-quantitative culture
• If the catheter tip culture subsequently returns ≥15 CFU, the newly placed catheter should be removed and a new catheter inserted at a different site³