What is the appropriate antibiotic (abx) regimen for an adult patient with yeast and Enterococcus faecalis in both urine and blood cultures?

Treatment of Yeast and Enterococcus faecalis in Urine and Blood Cultures

For this dual bloodstream and urinary infection with E. faecalis and yeast, treat with ampicillin 2 g IV every 4-6 hours PLUS an echinocandin (caspofungin, micafungin, or anidulafungin) for critically ill patients, or fluconazole if the patient is stable and Candida albicans is confirmed. 1, 2, 3

Immediate Assessment Required

Before initiating therapy, you must determine:

• Severity of illness: APACHE II score, hemodynamic stability, and organ dysfunction 3
• Healthcare-associated vs. community-acquired: Recent hospitalizations, prior antibiotics, immunosuppression, or prosthetic devices 3
• Presence of endocarditis risk factors: New murmur, valvular heart disease, prosthetic valves, or embolic phenomena 3

Enterococcus faecalis Treatment Strategy

First-Line Antibacterial Therapy

Ampicillin is the gold standard for E. faecalis bloodstream infections, as 97% of E. faecalis strains remain ampicillin-susceptible despite only 3% being multidrug-resistant 1, 2. The recommended dosing is ampicillin 2 g IV every 4-6 hours (or 200 mg/kg/day in divided doses) 3, 2.

When to Add Gentamicin for Synergy

Add gentamicin 3 mg/kg/day IV in divided doses (every 8 hours, NOT once daily) if:

• Endocarditis is suspected or confirmed (treat for 4-6 weeks for native valve, minimum 6 weeks for prosthetic valve) 3
• Severe sepsis with hemodynamic instability requiring bactericidal activity 3, 2
• Healthcare-associated infection with prosthetic materials 3

Critical pitfall: Gentamicin must be dosed multiple times daily (every 8 hours) for enterococcal synergy, NOT once-daily dosing, with target 1-hour peak of ~3 μg/mL and trough <1 μg/mL 3. Duration is typically 2 weeks when combined with ampicillin, though some experts recommend 2-6 weeks depending on clinical response 3.

Alternative for Penicillin Allergy

If the patient has documented severe penicillin allergy, use vancomycin 30 mg/kg/day IV in 2 divided doses (target trough 10-20 μg/mL) PLUS gentamicin for 6 weeks 3, 2. However, ampicillin-gentamicin is superior to vancomycin-gentamicin and should be preferred whenever possible 3, 2.

If Vancomycin-Resistant E. faecalis (VRE)

Linezolid 600 mg IV/PO every 12 hours is the preferred agent for vancomycin-resistant E. faecalis, with proven clinical efficacy and cure rates of 67% in documented VRE infections 3, 1, 2, 4. Alternative options include daptomycin 8-12 mg/kg/day IV 3, 1.

Antifungal Therapy for Candidemia

Critical Patient or Unknown Candida Species

For critically ill patients or when Candida species is unknown, initiate an echinocandin immediately (caspofungin, micafungin, or anidulafungin) 3. This recommendation is based on superior outcomes in severe infections and broader coverage of fluconazole-resistant species 3.

Stable Patient with Confirmed C. albicans

Fluconazole is appropriate if the patient is hemodynamically stable AND Candida albicans is confirmed on culture 3. However, do not wait for speciation in critically ill patients—start with an echinocandin and de-escalate to fluconazole once C. albicans is confirmed and the patient improves 3.

Duration of Antifungal Therapy

Treat candidemia for 14 days after the first negative blood culture AND resolution of symptoms 3. If endocarditis is present, treatment duration extends to 6 weeks minimum 3.

Mandatory Workup for Endocarditis

Obtain transesophageal echocardiography (TEE) if any of the following are present:

• New cardiac murmur or embolic phenomena 3
• Persistent bacteremia or fever >72 hours despite appropriate antibiotics 3
• Prosthetic valve or other intravascular prosthetic material 3
• Radiographic evidence of septic pulmonary emboli 3

Enterococcal bacteremia carries a relatively low risk of endocarditis (1.5% in one large series), but the consequences of missing it are catastrophic 3. Infectious disease consultation is mandatory for enterococcal endocarditis management 1, 2.

Treatment Duration for Non-Endocarditis Infections

• Uncomplicated bacteremia with catheter removal: 7-14 days after catheter removal and blood culture clearance 3, 1, 2
• Complicated bacteremia without endocarditis: 14 days minimum 3, 1
• Urinary tract infection with bacteremia: 14 days 2, 5

Critical Pitfalls to Avoid

Never use cephalosporins for enterococcal coverage—they have zero intrinsic activity against enterococci despite in vitro synergy when combined with ampicillin 1, 2. This is a common error in empiric sepsis protocols.

Do not assume E. faecium has the same susceptibility as E. faecalis—E. faecium has intrinsic penicillin resistance in most strains and requires vancomycin or linezolid empirically 3, 1. However, 83% of enterococcal infections are E. faecalis 5, making ampicillin the appropriate empiric choice pending speciation.

Avoid amphotericin B as initial antifungal therapy due to significant nephrotoxicity, especially problematic when combining with aminoglycosides for enterococcal synergy 3.

Tailoring Therapy Based on Susceptibilities

Once culture and susceptibility results return, narrow therapy immediately 3. If E. faecalis is ampicillin-susceptible (MIC ≤8 mg/L), continue ampicillin and discontinue broader agents 2. If Candida albicans is confirmed and the patient is stable, consider switching from echinocandin to fluconazole 3.