What is the recommended antibiotic therapy for uncomplicated acute cystitis?

Recommended Antibiotic Therapy for Uncomplicated Acute Cystitis

First-line treatment for uncomplicated acute cystitis includes nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days), trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) if local resistance is <20%, or fosfomycin trometamol (3 g single dose). 1, 2

First-Line Treatment Options

1. Nitrofurantoin Monohydrate/Macrocrystals

• Dosage: 100 mg twice daily for 5 days
• Advantages:
  • Minimal resistance patterns
  • Limited collateral damage to normal flora
  • Efficacy comparable to 3-day trimethoprim-sulfamethoxazole regimen 1
  • Equivalent microbiological eradication rates to fosfomycin (76-82%) 3
• Cautions:
  • Not recommended for patients with significant renal impairment (GFR <30 ml/min/1.73m²)
  • Rare but possible systemic inflammatory response syndrome 4

2. Trimethoprim-Sulfamethoxazole (TMP-SMX)

• Dosage: 160/800 mg (1 double-strength tablet) twice daily for 3 days
• Advantages:
  • Proven efficacy in numerous clinical trials
  • Short treatment duration (3 days)
  • High microbiological eradication rate (98%) 3
• Key consideration: Only appropriate when local resistance rates of uropathogens do not exceed 20% or when the infecting strain is known to be susceptible 1, 2

3. Fosfomycin Trometamol

• Dosage: 3 g single dose
• Advantages:
  • Convenient single-dose administration
  • Minimal resistance patterns
  • Limited collateral damage to normal flora
• Limitations:
  • Inferior efficacy compared to standard short-course regimens
  • Lower microbiological eradication rates (82%) compared to TMP-SMX and ciprofloxacin (98%) 1, 3
  • Equivalent to nitrofurantoin in clinical efficacy 3

Alternative Options

Fluoroquinolones (e.g., Ciprofloxacin)

• Should be reserved for more invasive infections or when first-line agents cannot be used 2, 5
• Higher risk of collateral damage and increasing resistance concerns
• High microbiological eradication rates (98%) 3

Beta-lactams (e.g., Amoxicillin-Clavulanate, Cephalexin)

• Not recommended as first-line empirical therapy 1, 5
• Less effective than other options for uncomplicated cystitis
• Consider only when first-line agents cannot be used
• Cephalexin 500 mg twice daily for 5-7 days may be an alternative option 2

Clinical Decision Algorithm

1. Assess for uncomplicated cystitis:

   • Female patient with dysuria, frequency, urgency
   • No fever, flank pain, or systemic symptoms
   • No anatomical or functional abnormalities of urinary tract
   • No recent urinary instrumentation or hospitalization

2. Select appropriate antibiotic:

   • First choice: Nitrofurantoin 100 mg BID for 5 days (if normal renal function)
   • Alternative first choice: TMP-SMX 160/800 mg BID for 3 days (if local E. coli resistance <20%)
   • Alternative first choice: Fosfomycin 3 g single dose (if compliance is a concern)

3. Consider fluoroquinolones or beta-lactams only if:

   • Patient has contraindications to all first-line agents
   • Known resistance to first-line agents
   • Previous treatment failure with first-line agents

Important Clinical Considerations

• Urine culture is not routinely necessary for uncomplicated cystitis but should be obtained if pyelonephritis is suspected or symptoms recur within 2-4 weeks 6, 5
• Immediate antimicrobial therapy is recommended rather than delayed treatment 5
• For recurrent uncomplicated cystitis, consider patient-initiated therapy where appropriate patients can self-start antibiotics at symptom onset 7
• Monitor for treatment failure and consider urine culture if symptoms persist beyond expected treatment duration

Common Pitfalls to Avoid

1. Using fluoroquinolones as first-line therapy (increases resistance and collateral damage)
2. Prescribing TMP-SMX in areas with high resistance rates (>20%)
3. Using nitrofurantoin in patients with significant renal impairment
4. Treating asymptomatic bacteriuria (except in pregnancy)
5. Prescribing unnecessarily long courses of antibiotics
6. Failing to consider local resistance patterns when selecting empiric therapy