What is the recommended oral antibiotic for uncomplicated cystitis?

Recommended Oral Antibiotic for Uncomplicated Cystitis

Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days) is the recommended first-line oral antibiotic for uncomplicated cystitis in women, based on its high efficacy (88-93% clinical cure rates), minimal resistance patterns, and limited collateral damage to the microbiome. 1

First-Line Treatment Options

The Infectious Diseases Society of America prioritizes three antibiotics as first-line agents, with nitrofurantoin leading the recommendations: 1

• Nitrofurantoin monohydrate/macrocrystals: 100 mg twice daily for 5 days

  • Clinical cure rates: 88-93% 1
  • Bacterial cure rates: 81-92% 1
  • Equivalent efficacy to ciprofloxacin (93% vs 95%) and trimethoprim-sulfamethoxazole (93% vs 95%) 1
  • Minimal resistance and collateral damage 1

• Trimethoprim-sulfamethoxazole (Bactrim DS): 160/800 mg twice daily for 3 days

  • Only use when local E. coli resistance is documented <20% 1, 2
  • Clinical cure rates: 90-100% for susceptible organisms 2
  • Efficacy drops dramatically to 41-54% against resistant strains 1, 2
  • Avoid if patient used this antibiotic in preceding 3-6 months or traveled outside the United States recently 2

• Fosfomycin trometamol: 3 g single oral dose 1, 3

  • Clinical cure rate: approximately 90% 1
  • Microbiological cure rate: 78% (lower than nitrofurantoin's 86%) 1
  • Convenient single-dose regimen 3
  • FDA-approved specifically for uncomplicated cystitis in women 3

Alternative Agents (Reserve for When First-Line Cannot Be Used)

• Fluoroquinolones (ciprofloxacin, levofloxacin): 3-day regimens 1

  • Highly effective but should be reserved for more serious infections like pyelonephritis 1, 2
  • Promote significant collateral damage and resistance 1
  • Resistance rates still <10% in most regions but rising 2

• β-Lactam agents (amoxicillin-clavulanate, cefdinir, cefaclor, cefpodoxime-proxetil): 3-7 day regimens 1

  • Generally inferior efficacy compared to first-line agents 1
  • More adverse effects 1
  • Use only when first-line options unavailable 1

Antibiotics to Avoid

• Amoxicillin or ampicillin alone: Do not use empirically due to poor efficacy and high worldwide resistance rates 1

Treatment Algorithm

Step 1: Confirm diagnosis of uncomplicated cystitis (frequency, dysuria, no fever, no flank pain, no comorbidities) 4

Step 2: Prescribe nitrofurantoin monohydrate/macrocrystals 100 mg twice daily for 5 days as first choice 1

Step 3: If nitrofurantoin contraindicated (renal impairment, last trimester pregnancy), consider: 1, 2

• Fosfomycin 3 g single dose (second choice)
• Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (only if local resistance <20% and no recent antibiotic use)

Step 4: Reserve fluoroquinolones only when all first-line agents cannot be used 1

Critical Caveats

• The 20% resistance threshold for trimethoprim-sulfamethoxazole is crucial: Above this level, treatment failures outweigh benefits 2
• Hospital antibiograms overestimate community resistance: Use local outpatient surveillance data when available 2
• Each additional day of antibiotics beyond recommended duration increases adverse events by 5% without added benefit 2
• Nitrofurantoin is contraindicated in any degree of renal impairment and in the last trimester of pregnancy 2, 5
• No routine post-treatment urine culture needed if symptoms resolve 6
• If symptoms persist or recur within 2 weeks: Obtain urine culture and consider 7-day regimen with alternative agent 6

Special Populations

• Men with UTI: Require 7 days of treatment (not 3 days) with trimethoprim-sulfamethoxazole 160/800 mg twice daily 2
• Women with diabetes: Treat similarly to women without diabetes if no voiding abnormalities present 7
• Patients with penicillin allergy: Nitrofurantoin remains first-line choice 6
• Patients with both penicillin and sulfa allergies: Use nitrofurantoin or fosfomycin 6