Recommended Antibiotic Dosing for Uncomplicated UTI in Females
For uncomplicated cystitis in women, prescribe nitrofurantoin 100 mg twice daily for 5 days as the preferred first-line agent, with trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days or fosfomycin 3 g single dose as alternatives. 1, 2
First-Line Treatment Options
The following regimens are recommended based on current guidelines:
Nitrofurantoin (Preferred)
- Nitrofurantoin monohydrate/macrocrystals: 100 mg twice daily for 5-7 days 1, 2, 3
- Clinical cure rates of 88-93% 2
- Lowest risk of treatment failure compared to other first-line agents 4
- Do not use if pyelonephritis is suspected 2
Trimethoprim-Sulfamethoxazole (TMP-SMX)
- 160/800 mg twice daily for 3 days 1, 5, 3
- Only use if local E. coli resistance is <20% or susceptibility is confirmed 2, 5
- Higher treatment failure risk than nitrofurantoin (1.6% absolute increase in prescription switches and 0.2% increase in pyelonephritis) 4
Fosfomycin
- 3 g single oral dose 1, 2, 5, 3
- Convenient single-dose regimen with slightly lower efficacy than nitrofurantoin 2
Second-Line Options
Fluoroquinolones should be reserved for complicated infections or resistant organisms, not used as first-line therapy 1, 5:
- Ciprofloxacin or levofloxacin for 3 days if needed 1
- High propensity for adverse effects and resistance concerns 1, 5
Treatment Duration Rationale
The 5-day nitrofurantoin regimen is based on:
- Consistent recommendations from IDSA/ESCMID and European Association of Urology guidelines 1, 2, 5
- Equivalent efficacy to 3-day TMP-SMX regimens 2
- Optimal balance between efficacy and minimizing adverse effects 2
When to Obtain Urine Culture
Do not routinely obtain urine culture for typical uncomplicated cystitis in women 5, 3. Culture is indicated only for:
- Recurrent infections 5, 3
- Treatment failure 5, 3
- History of resistant organisms 3
- Atypical symptoms 5, 3
- Pregnancy 5
Management of Treatment Failure
If symptoms persist at end of treatment or recur within 2 weeks 5:
- Obtain urine culture with susceptibility testing 5
- Retreat with a 7-day regimen using a different antibiotic class 5
Common Pitfalls to Avoid
- Avoid β-lactams (amoxicillin-clavulanate, cefpodoxime) as empiric first-line therapy - they are less effective than nitrofurantoin, TMP-SMX, or fosfomycin 6
- Do not treat asymptomatic bacteriuria 5
- Do not perform routine post-treatment cultures in asymptomatic patients 2, 5
- Avoid nitrofurantoin if early pyelonephritis is suspected (flank pain, fever, nausea/vomiting) 2
Special Considerations
For women with diabetes and no voiding abnormalities, treat the same as women without diabetes 6. Real-world evidence demonstrates nitrofurantoin has the lowest risk of progression to pyelonephritis (0.3%) compared to TMP-SMX (0.5%) 4, making it the safest empiric choice when resistance patterns are unknown.