What is the optimal antibiotic treatment regimen for a patient diagnosed with chronic prostatitis caused by Enterococcus faecalis, considering the antibiogram results showing resistance to fluoroquinolones and sensitivity to amoxicillin at an increased dose?

Treatment of Chronic Prostatitis Caused by Enterococcus faecalis

For chronic prostatitis caused by Enterococcus faecalis resistant to fluoroquinolones but sensitive to amoxicillin at increased dose (S=2), the optimal treatment regimen is high-dose amoxicillin 1g orally three times daily for 4-6 weeks.

Rationale for Treatment Selection

Antibiotic Choice

• The patient's antibiogram shows resistance to fluoroquinolones but sensitivity to amoxicillin at an increased dose (S=2)
• Amoxicillin is effective against E. faecalis through inhibition of cell wall biosynthesis 1
• While fluoroquinolones are commonly used for prostatitis, they would be ineffective in this case due to confirmed resistance 2

Dosing Considerations

• Higher doses of amoxicillin are required for:
  • Adequate prostatic tissue penetration
  • Overcoming the relative impermeability of the chronically inflamed prostate
  • Achieving bactericidal concentrations against E. faecalis with reduced sensitivity (S=2)

Treatment Duration

• 4-6 weeks of therapy is recommended for chronic bacterial prostatitis to:
  • Ensure complete eradication of the infection
  • Prevent relapse
  • Allow sufficient time for resolution of inflammation

Alternative Treatment Options

If the patient fails to respond to high-dose amoxicillin or develops intolerance:

1. Amoxicillin-clavulanate: 875/125 mg orally twice daily for 4-6 weeks

   • Provides additional coverage if beta-lactamase production is present

2. Ampicillin plus gentamicin (if parenteral therapy is needed):

   • Ampicillin 2g IV every 4-6 hours plus gentamicin 3 mg/kg/day IV/IM in divided doses 3, 4
   • Consider only for severe cases requiring hospitalization

3. Vancomycin:

   • For patients with severe penicillin allergy
   • 30 mg/kg/day IV in 2 divided doses 3

Monitoring Recommendations

• Clinical response assessment at 2 weeks to determine continuation
• Follow-up culture of expressed prostatic secretions after completion of therapy
• Monitor for adverse effects:
  • Gastrointestinal symptoms (diarrhea, nausea)
  • Allergic reactions
  • Superinfection (Candida)

Important Considerations

• Prostate penetration of antibiotics is a critical factor in treatment success
• E. faecalis strains are often resistant to tetracycline (97.5%), erythromycin (95%), and trimethoprim/sulfamethoxazole (31.5%), making these poor empiric choices 2
• Chronic bacterial prostatitis requires longer treatment courses than acute prostatitis (4-6 weeks vs. 2 weeks) 5
• Adequate hydration should be maintained throughout treatment
• Anti-inflammatory medications may be added for symptom relief

Treatment Pitfalls to Avoid

• Using fluoroquinolones despite documented resistance
• Insufficient treatment duration (less than 4 weeks)
• Inadequate dosing that fails to achieve therapeutic concentrations in prostatic tissue
• Failure to distinguish between bacterial and non-bacterial forms of prostatitis
• Not considering patient compliance with long-term oral therapy

By following this treatment approach with high-dose amoxicillin for 4-6 weeks, you maximize the chances of eradicating the E. faecalis infection while minimizing the risk of treatment failure and recurrence.