Is amoxicillin (amoxicillin) effective as a follow-up treatment for Enterococcus Faecalis prostatitis after a regimen of linezolid (linezolid)?

Amoxicillin for Enterococcus Faecalis Prostatitis After Linezolid Treatment

Amoxicillin 500 mg orally every 8 hours is an effective follow-up treatment for Enterococcus faecalis prostatitis after a regimen of linezolid, particularly when the organism is susceptible to amoxicillin. 1, 2

Treatment Considerations for E. faecalis Prostatitis

• Ampicillin/amoxicillin is the drug of choice for enterococcal infections when the organism is susceptible, making it an appropriate follow-up option after linezolid therapy 1
• High-dose amoxicillin (500 mg PO every 8 hours) is recommended for enterococcal infections to achieve sufficient tissue penetration, including in the prostate 1
• Linezolid is typically used for vancomycin-resistant enterococci (VRE) infections, but prolonged use (>14-21 days) can lead to adverse effects like thrombocytopenia, making transition to oral amoxicillin beneficial 3, 4

Antimicrobial Selection Algorithm

1. Confirm susceptibility testing results:

   • Ensure E. faecalis isolate is susceptible to amoxicillin before initiating therapy 2
   • If beta-lactamase producing, consider amoxicillin-clavulanate instead 1

2. For amoxicillin-susceptible E. faecalis:

   • Prescribe amoxicillin 500 mg orally every 8 hours 1, 2
   • Duration typically 4-6 weeks for prostatitis to ensure complete eradication 1

3. For amoxicillin-resistant E. faecalis:

   • Continue linezolid 600 mg orally every 12 hours 1, 4
   • Consider alternative oral options based on susceptibility:
     • Nitrofurantoin (if limited to lower urinary tract) 5, 6
     • Fosfomycin (for uncomplicated UTI, not specifically studied for prostatitis) 1, 7

Clinical Evidence and Rationale

• Amoxicillin achieves high urinary concentrations that can overcome even relatively resistant strains of E. faecalis in the urogenital tract 1
• Clinical and microbiological eradication rates of 88.1% and 86% respectively have been reported with ampicillin/amoxicillin for enterococcal urinary tract infections 1, 2
• A case report of chronic prostatitis due to vancomycin-resistant Enterococcus faecium (more resistant than E. faecalis) showed that appropriate oral antibiotic therapy for 6 weeks resulted in long-lasting cure 6

Important Considerations and Pitfalls

• Prostate tissue penetration can be challenging for many antibiotics; amoxicillin achieves adequate levels when dosed appropriately 2, 7
• Always confirm susceptibility before switching from linezolid to amoxicillin, as resistance patterns can vary 5, 4
• Monitor for clinical response within 48-72 hours of initiating amoxicillin therapy 8
• If symptoms persist despite appropriate therapy, consider:
  • Prostatic abscess requiring drainage 8
  • Biofilm formation requiring longer duration of therapy 7
  • Development of resistance during therapy 4

Special Situations

• For patients with penicillin allergy, continue linezolid or consider alternative agents based on susceptibility testing 3, 4
• For patients with renal impairment, adjust amoxicillin dosing accordingly while maintaining adequate tissue concentrations 1, 2