What is the best course of action for a patient with persistent coagulase-negative staph (CoNS) infection despite treatment with cephazolin (Ancef), who has a permcath (peripherally inserted central catheter)?

Remove the Permcath and Switch to Vancomycin

For persistent coagulase-negative staph (CoNS) bacteremia despite cefazolin treatment in a patient with a permcath, you must remove the catheter and switch to vancomycin, as treatment failure with persistent positive cultures is a clear indication for catheter removal. 1

Why Catheter Removal is Mandatory

• Persistent bacteremia or fever despite appropriate antibiotics mandates immediate catheter removal 1
• Treatment failure manifesting as persistent positive blood cultures after antibiotics have been started is the strongest indication for removing the catheter 1
• Attempting catheter salvage with cefazolin alone has already failed in this case, making removal non-negotiable 2, 3

Antibiotic Management

Switch from Cefazolin to Vancomycin

• Start vancomycin immediately because the CoNS strain is likely resistant to cefazolin (evidenced by persistent bacteremia) and may have methicillin resistance 1
• Empirical vancomycin is recommended for CoNS catheter-related bloodstream infections, with de-escalation to a semisynthetic penicillin only if the isolate proves susceptible AND the patient responds clinically 1
• For hemodialysis patients, dose vancomycin at 20 mg/kg after each dialysis session 3

Why Cefazolin Failed

• While cefazolin can be effective for methicillin-susceptible CoNS 4, 5, persistent bacteremia indicates either:
  • Methicillin resistance (common in CoNS, occurring in 30-70% of isolates) 6
  • Vancomycin heteroresistance (present in up to 39% of CoNS isolates) 7
  • Biofilm formation on the catheter that antibiotics cannot penetrate 1

Treatment Duration After Catheter Removal

• Treat with vancomycin for 5-7 days if the catheter is removed and the infection is uncomplicated 1
• Extend treatment to 10-14 days if there are signs of complicated infection 1
• Treat for 4-6 weeks if there is persistent bacteremia after catheter removal, endocarditis, or suppurative thrombophlebitis 1, 3

Evaluation for Metastatic Infection

• Obtain repeat blood cultures 2-3 days after catheter removal to confirm clearance 2, 3
• Consider transesophageal echocardiography if bacteremia persists >72 hours after catheter removal or if S. aureus is identified (though less commonly needed for CoNS) 3
• Assess for signs of tunnel infection, pocket abscess, or septic thrombophlebitis 2, 3

Catheter Replacement Strategy

• Place a temporary catheter at a different anatomical site immediately after removing the infected permcath 2, 3
• Wait until blood cultures are negative before placing a new permanent catheter 3
• Do not exchange over a guidewire in the setting of persistent bacteremia, as this has high failure rates 1, 2

Common Pitfalls to Avoid

• Never attempt antibiotic lock therapy when there is already treatment failure with systemic antibiotics - this approach has a 50% failure rate even in ideal circumstances and is contraindicated with persistent bacteremia 1
• Do not continue cefazolin hoping for delayed response - persistent bacteremia after 48-72 hours of appropriate therapy mandates catheter removal 1, 2
• Avoid using vancomycin prophylactically in the future, as prior vancomycin exposure increases risk of heteroresistant CoNS 7