What is the treatment for Enterococcus (E.) faecalis and Staphylococcus (Staph) aureus in a foot culture?

Treatment for Enterococcus faecalis and Staphylococcus aureus in Foot Culture

For diabetic foot infections with E. faecalis and S. aureus, ampicillin-sulbactam is the most appropriate first-line treatment, with vancomycin as an alternative for penicillin-allergic patients or MRSA concerns. 1

Antibiotic Selection Based on Infection Severity

Mild Infections

• For mild infections with minimal cellulitis, narrow-spectrum antibiotics targeting gram-positive cocci are usually sufficient 1
• Oral therapy options:
  • Amoxicillin-clavulanate (covers both E. faecalis and methicillin-susceptible S. aureus) 1
  • Clindamycin (if S. aureus is the predominant pathogen and patient is not allergic) 1
  • For penicillin-allergic patients: trimethoprim-sulfamethoxazole (effective against S. aureus but may have limited activity against E. faecalis) 1

Moderate to Severe Infections

• Parenteral therapy is recommended initially for moderate to severe infections 1
• First-line options:
  • Ampicillin-sulbactam 3g IV every 6 hours (effective against both E. faecalis and S. aureus) 1
  • Piperacillin-tazobactam (for broader coverage if gram-negative pathogens are also suspected) 1
• For penicillin-allergic patients or MRSA concerns:
  • Vancomycin 30 mg/kg per 24h IV in 2 equally divided doses (effective against both E. faecalis and MRSA) 1
  • Consider adding gentamicin 3 mg/kg per 24h IV in 3 divided doses for synergistic effect in severe infections 1

Special Considerations

MRSA Concerns

• If MRSA is suspected or confirmed:
  • Vancomycin is recommended as first-line therapy 1
  • Daptomycin 6 mg/kg IV daily is an effective alternative, with activity against both E. faecalis and S. aureus (including MRSA) 2
  • Linezolid may be considered for patients who cannot tolerate vancomycin 1

Beta-lactamase Producing Strains

• Rarely, E. faecalis may produce beta-lactamase, making it resistant to ampicillin 1
• These strains remain susceptible to ampicillin-sulbactam and vancomycin 1
• For S. aureus, beta-lactamase production is common, necessitating beta-lactamase-stable agents 3

Duration of Therapy

• For soft tissue infections without bone involvement: 1-2 weeks for mild infections and 2-3 weeks for moderate to severe infections 1
• Continue antibiotic therapy until resolution of infection signs but not through complete wound healing 1
• Consider longer duration if there is underlying osteomyelitis 1

Monitoring and Follow-up

• Monitor clinical response within 48-72 hours of initiating therapy 1
• Adjust antibiotic regimen based on culture and susceptibility results when available 1
• For patients receiving aminoglycosides, monitor renal function and drug levels (peak 3-4 μg/mL, trough <1 μg/mL for gentamicin) 1

Important Caveats

• Avoid prolonged aminoglycoside therapy due to risk of nephrotoxicity and ototoxicity 1
• Consider short-course (approximately 2 weeks) gentamicin therapy when used in combination with beta-lactams to reduce toxicity risk 1
• Diabetic foot infections often require surgical debridement in addition to antibiotic therapy 1
• Tailor therapy based on wound culture results when available to ensure appropriate coverage and avoid unnecessary broad-spectrum antibiotics 1

Combination Therapy Considerations

• Double beta-lactam regimens (ampicillin plus ceftriaxone) may be effective for E. faecalis infections when aminoglycosides cannot be used 1
• Daptomycin combined with beta-lactams has shown synergistic effects against resistant strains 1, 2
• For polymicrobial infections including anaerobes, add metronidazole to regimens that lack anaerobic coverage 1