Enterococcus faecalis Bacteremia: Sources and Management
Common Sources of E. faecalis Bacteremia
The urinary tract is the most frequently identified source of E. faecalis bacteremia (25-36%), followed by intra-abdominal infections (13%), vascular catheters (15%), and wounds/abscesses (9-11%). 1, 2, 3
Source Distribution
- Urinary tract infections: 25-36% of cases 1, 2
- Intra-abdominal/pelvic sources: 13% 2
- Central venous catheters: 15% 1
- Burn and decubital wounds: 11% 2
- Unknown/primary bacteremia: 33-49% of cases 1, 3
Important Clinical Context
- 83-85% of E. faecalis bacteremia is nosocomial and associated with prior invasive procedures 3
- Polymicrobial bacteremia occurs in a minority of cases but is associated with significantly higher mortality 1
- The gastrointestinal tract may serve as an alternate source through bacterial translocation, particularly when no other source is identified 1
- Prior broad-spectrum antibiotic therapy (particularly cephalosporins, imipenem, aztreonam, or ciprofloxacin) precedes 60% of cases, selecting for enterococcal overgrowth 2, 3
Treatment Approach
Catheter-Related Bloodstream Infections (CRBSI)
For E. faecalis catheter-related bacteremia, the catheter can be retained with systemic antibiotic therapy, unlike S. aureus which mandates removal. 4
Antibiotic Selection for CRBSI
- Ampicillin is the preferred first-line agent for susceptible strains 4
- Vancomycin should be used for ampicillin-resistant strains 4
- For ampicillin- and vancomycin-resistant enterococci, use linezolid or daptomycin based on susceptibility testing 4
Duration and Catheter Management
- Treatment duration is 7-14 days if no endocarditis or metastatic infection is present 4
- If the long-term catheter is retained, combine systemic antibiotics with antibiotic lock therapy (gentamicin + ampicillin) 4
- Remove the catheter if bacteremia persists >72 hours after initiating appropriate therapy 4
Non-Catheter Related Bacteremia
Ampicillin remains the drug of choice for ampicillin-susceptible E. faecalis bacteremia from any source. 4, 3
First-Line Therapy
- Ampicillin monotherapy is appropriate for uncomplicated bacteremia 4
- Combination therapy with gentamicin + ampicillin showed benefit only when attempting catheter salvage, not for improved survival in general 4, 2
- High-dose aminoglycosides added to penicillins did not improve mortality in one study 2
Resistant Organisms
- For vancomycin-resistant E. faecalis (rare, only 2% of strains): Use ampicillin if susceptible, or linezolid/daptomycin if ampicillin-resistant 4, 5
- High-dose daptomycin (10-12 mg/kg/day) is preferred for serious infections, particularly for vancomycin-tolerant strains 5, 6
- Daptomycin 12 mg/kg IV q24h successfully cleared vancomycin-tolerant E. faecalis bacteremia in a documented case 6
Endocarditis Evaluation
Transesophageal echocardiography (TEE) should be performed if clinical signs of endocarditis are present, but routine TEE is not required for all E. faecalis bacteremia. 4
Indications for TEE
- New cardiac murmur or embolic phenomena 4
- Prolonged bacteremia or fever >72 hours despite appropriate therapy 4
- Presence of prosthetic valve or other endovascular foreign bodies 4
- The risk of endocarditis is higher with E. faecalis than E. faecium (though still relatively low at 1.5% in one large study) 4
Critical Pitfalls to Avoid
- Do not assume all enterococcal bacteremia requires catheter removal—E. faecalis CRBSI can often be treated with catheter retention, unlike S. aureus 4
- Persistent bacteremia >4 days is independently associated with mortality and warrants catheter removal and extended evaluation 4
- Inadequate empirical antibiotic therapy is a significant predictor of mortality—ensure coverage if enterococcal bacteremia is suspected in high-risk patients 4, 3
- Do not routinely use combination therapy for uncomplicated bacteremia—monotherapy with ampicillin is sufficient 4, 2
Prognostic Factors
Mortality from E. faecalis bacteremia ranges from 10-24%, with only 10% directly attributable to the infection itself. 1, 3