What is the indication for antibiotic prophylaxis in women with recurrent cystitis?

Indications for Antibiotic Prophylaxis in Women with Recurrent Cystitis

Antibiotic prophylaxis should be considered only after counseling and behavioral modifications have been attempted and proven unsuccessful in women with recurrent urinary tract infections (rUTIs), defined as ≥3 UTIs in one year or ≥2 UTIs in 6 months. 1, 2

Diagnostic Criteria for Recurrent UTIs

• Confirmation of recurrent UTIs requires:
  • ≥3 culture-positive UTIs in one year OR
  • ≥2 culture-positive UTIs in 6 months 2
• Before initiating prophylaxis, eradication of previous UTI must be confirmed with a negative urine culture 1-2 weeks after treatment 1

Algorithm for Antibiotic Prophylaxis Decision-Making

1. First-line approach: Non-antimicrobial measures

   • Behavioral modifications:
     • Adequate hydration
     • Voiding after intercourse
     • Avoiding prolonged urine retention
     • Avoiding spermicide use
     • Avoiding sequential anal and vaginal intercourse 1

2. Second-line approach: Non-antibiotic prophylaxis options

   • Vaginal estrogen in postmenopausal women 1, 2
   • Methenamine hippurate (1g twice daily) 2
   • Cranberry products with minimum 36 mg/day proanthocyanidin A 1, 2

3. Third-line approach: Antibiotic prophylaxis

   • Indications for continuous daily prophylaxis:

     • Documented ≥3 UTIs per year or ≥2 UTIs in 6 months
     • Failure of non-antimicrobial and non-antibiotic prophylaxis measures
     • Significant impact on quality of life 1, 2

   • Indications for post-coital prophylaxis:

     • Clear temporal relationship between sexual intercourse and UTI episodes
     • Lower antibiotic exposure compared to daily prophylaxis 1, 3

Specific Antibiotic Prophylaxis Regimens

Post-coital Prophylaxis

• Single dose within 2 hours after intercourse:
  • Nitrofurantoin 50-100mg
  • Trimethoprim-sulfamethoxazole single strength
  • Cephalexin 250mg 1, 3

Continuous Daily Prophylaxis

• Duration: 6-12 months
• Options:
  • Nitrofurantoin 50-100mg daily
  • Trimethoprim-sulfamethoxazole 40/200mg daily
  • Cephalexin 125-250mg daily 1, 2

Important Considerations and Caveats

• Antibiotic selection: Base on previous culture results, local resistance patterns, and patient allergies 1, 2
• Avoid fluoroquinolones: High resistance rates (>80%) and increased risk of C. difficile infection 2
• Preferred option: Nitrofurantoin due to lower resistance rates and less impact on gut microbiome 2
• Duration of prophylaxis: Typically 6-12 months, then reassess 1
• Patient-initiated treatment: Consider self-start therapy for select patients with good understanding of their symptoms 2, 4

Evidence Strength and Limitations

• Continuous antibiotic prophylaxis reduces UTI recurrence by approximately 85-95% compared to placebo 1, 5
• Post-coital prophylaxis is highly effective with infection rates of 0.3 per patient-year versus 3.6 with placebo 3
• Post-coital and daily prophylaxis show similar efficacy in women with intercourse-related UTIs 6
• The benefit must be weighed against risks of adverse effects and development of antimicrobial resistance 5, 4

Remember that antibiotic prophylaxis should be reserved for cases where non-antimicrobial measures have failed, and the choice of antibiotic should be guided by previous culture results and local resistance patterns to minimize both morbidity and mortality associated with recurrent UTIs.