What is the recommended treatment for a patient with a catheter-related bloodstream infection (CRBSI) due to Enterococcus faecalis and Enterobacter cloacae?

Management of Polymicrobial CRBSI with Enterococcus faecalis and Enterobacter cloacae

Remove the catheter immediately and treat with ampicillin (if E. faecalis is susceptible) plus a fourth-generation cephalosporin or carbapenem (based on E. cloacae susceptibilities) for 7-14 days after catheter removal in uncomplicated cases. 1, 2, 3

Immediate Catheter Management

The catheter must be removed—this is non-negotiable for gram-negative CRBSI and strongly recommended for enterococcal infection. 1, 2, 3

• Short-term catheters: Remove immediately upon diagnosis 1, 2, 3
• Long-term catheters: Remove promptly, especially given the polymicrobial nature with a gram-negative organism 1, 2
• Do not attempt catheter salvage with Enterobacter cloacae present, as gram-negative bacilli require catheter removal for cure 2
• The only scenario where enterococcal CRBSI catheter retention might be considered is with long-term catheters in uncomplicated cases without gram-negative co-infection, but this does not apply to your polymicrobial scenario 1, 3

Empirical Antibiotic Therapy (Before Susceptibilities)

Start broad-spectrum coverage immediately for both organisms:

• For E. faecalis coverage: Ampicillin or vancomycin 1, 3
• For E. cloacae coverage: Fourth-generation cephalosporin (cefepime), carbapenem (meropenem/imipenem), or piperacillin-tazobactam based on local resistance patterns 2
• If critically ill or septic: Use combination therapy with two different classes of gram-negative agents until susceptibilities return 2

Definitive Antibiotic Therapy (After Susceptibilities)

De-escalate to the narrowest-spectrum regimen that covers both organisms once susceptibility data are available. 2, 3

For Enterococcus faecalis:

• Ampicillin is the drug of choice if susceptible (E. faecalis is typically ampicillin-susceptible in >98% of cases) 1, 3
• Vancomycin if ampicillin-resistant 1, 3
• Linezolid or daptomycin for ampicillin- and vancomycin-resistant strains 1, 3

For Enterobacter cloacae:

• Fourth-generation cephalosporin (cefepime) if susceptible 2
• Carbapenem (meropenem or imipenem) if resistant to cephalosporins or if AmpC β-lactamase production suspected 2
• Fluoroquinolone (ciprofloxacin or levofloxacin) based on susceptibility 2

Combination Therapy Considerations:

• The role of adding an aminoglycoside to ampicillin for E. faecalis is unresolved in CRBSI without endocarditis 1, 3
• However, one retrospective study found combination therapy with gentamicin and ampicillin more effective than monotherapy when catheters were retained, though this is not applicable since your catheter should be removed 1, 4
• Do not use combination therapy for E. cloacae once susceptibilities confirm adequate single-agent coverage and the patient is clinically stable 2

Treatment Duration

Standard duration is 7-14 days after catheter removal for uncomplicated CRBSI. 1, 2, 3, 5

• 7 days may be sufficient for uncomplicated enterococcal CLABSI with prompt catheter removal and clinical improvement 5
• Extend to 4-6 weeks if any of the following complications occur: 1, 2, 3
  • Persistent bacteremia >72 hours after catheter removal and appropriate antibiotics
  • Endocarditis
  • Suppurative thrombophlebitis
  • Metastatic infection
• 6-8 weeks for osteomyelitis if this complication develops 2

Critical Monitoring and Follow-up

Obtain follow-up blood cultures 72 hours after initiating appropriate therapy. 2, 3

• If cultures remain positive at 72 hours, evaluate for: 2, 3
  • Endovascular infection (perform transesophageal echocardiography)
  • Suppurative thrombophlebitis
  • Metastatic seeding (especially osteomyelitis, epidural abscess)

Perform transesophageal echocardiography (TEE) if: 1, 3

• New murmur or embolic phenomena
• Bacteremia or fever persisting >72 hours despite appropriate therapy
• Prosthetic valve present
• Radiographic evidence of septic pulmonary emboli

Common Pitfalls to Avoid

• Do not use linezolid empirically before bacteremia is confirmed—it has been associated with increased mortality in patients without confirmed bacteremia 1
• Do not assume E. faecalis is vancomycin-resistant—only 2% of E. faecalis are vancomycin-resistant, so ampicillin is almost always appropriate 1
• Do not use third-generation cephalosporins for Enterobacter species due to inducible AmpC β-lactamase production leading to treatment failure 2
• Enterococcal bacteremia persisting >4 days is independently associated with mortality, so aggressive source control and appropriate antibiotics are critical 1, 3
• Do not delay catheter removal in polymicrobial bacteremia—the presence of gram-negative organisms mandates removal 2