How should I manage a catheter-related bloodstream infection when the catheter tip culture grows a levofloxacin-susceptible organism?

Management of Catheter-Related Infection with Levofloxacin-Susceptible Organism

Remove the catheter immediately and treat with systemic levofloxacin (or another appropriate fluoroquinolone like ciprofloxacin) for 7-14 days, depending on whether the infection is uncomplicated or complicated. 1

Immediate Actions

Catheter removal is mandatory for catheter-related bloodstream infections (CRBSI) caused by gram-negative bacilli, which are the most likely organisms to be levofloxacin-susceptible in this clinical context. 1 The guidelines are unequivocal: short-term catheters infected with gram-negative bacilli should be removed. 1

• Obtain two sets of blood cultures before initiating antibiotics—at least one drawn percutaneously and one through the catheter if still in place. 1, 2, 3
• Culture any purulent drainage from the exit site for Gram stain and culture. 1, 2
• Remove the catheter and culture the tip using semiquantitative (roll-plate) or quantitative methods. 1, 2

Antibiotic Selection and Duration

Once susceptibilities confirm levofloxacin sensitivity, transition to targeted therapy:

• For uncomplicated CRBSI with gram-negative bacilli: Treat for 7-14 days after catheter removal. 1
• For complicated infections (septic thrombosis, endocarditis, osteomyelitis, or metastatic seeding): Treat for 4-6 weeks for septic thrombosis/endocarditis or 6-8 weeks for osteomyelitis. 1

The 2001 IDSA guidelines specifically endorse oral fluoroquinolones like ciprofloxacin (and by extension levofloxacin) once the patient is stabilized and susceptibilities are known, due to their excellent oral bioavailability and tissue penetration. 1 This allows for step-down from IV to oral therapy in appropriate patients.

Determining Complicated vs. Uncomplicated Infection

Uncomplicated infection is defined as prompt clinical response to antibiotics and catheter removal, with no evidence of:

• Septic thrombosis 1
• Endocarditis 1
• Osteomyelitis 1
• Metastatic seeding to other sites 1

Workup for complications should include:

• Repeat blood cultures 48-72 hours after catheter removal to document clearance. 1
• For persistent bacteremia beyond 72 hours despite appropriate therapy, perform transesophageal echocardiography to rule out endocarditis. 3, 4
• Evaluate for septic thrombosis if there is ipsilateral neck, chest, or upper extremity swelling (for central lines) or pseudoaneurysm/embolic lesions (for arterial catheters). 1

Special Considerations for Gram-Negative Bacilli

The 2009 IDSA update emphasizes that certain multidrug-resistant gram-negative organisms (Acinetobacter baumannii, Pseudomonas species, Stenotrophomonas maltophilia) have a propensity for biofilm production and mandate catheter removal. 1 Even with levofloxacin susceptibility, do not attempt catheter salvage with antibiotic lock therapy for gram-negative CRBSI—the evidence for this approach is limited to small studies and primarily applies to coagulase-negative staphylococci. 1

Common Pitfalls to Avoid

• Do not leave the catheter in place for gram-negative CRBSI, even if the organism is susceptible to antibiotics. Unlike coagulase-negative staphylococci, gram-negative bacilli require catheter removal. 1
• Do not treat based on catheter tip culture alone without blood culture confirmation—a positive tip culture without bacteremia may represent colonization rather than true infection. 1
• Do not insert a new catheter at the same site immediately after removal—wait until blood cultures are negative and the patient has received at least 48 hours of appropriate antibiotics. 5
• Do not assume uncomplicated infection without ruling out metastatic complications, particularly if bacteremia persists beyond 72 hours. 1, 3

When Catheter Tip Culture is Positive but Blood Cultures are Negative

If the catheter tip grows >15 CFU by semiquantitative culture but blood cultures remain negative and the patient is febrile without another source:

• For gram-negative bacilli, close monitoring is recommended with repeat blood cultures. 1
• Some experts would administer a short course (5-7 days) of antibiotics if the patient has risk factors, though this is based on limited data. 1
• This scenario is less concerning than with S. aureus or Candida, which have higher rates of complications. 1