Antibiotics for Uncomplicated UTI in Healthy Adults
For uncomplicated cystitis in otherwise healthy adult women, prescribe nitrofurantoin 100 mg twice daily for 5 days, trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days (only if local resistance <20%), or fosfomycin 3 g single dose as first-line therapy. 1, 2
First-Line Treatment Options for Uncomplicated Cystitis
The choice among first-line agents depends on local resistance patterns and patient-specific factors:
Nitrofurantoin 100 mg twice daily for 5 days is recommended as a preferred first-line agent by multiple guidelines 1, 2. This agent has excellent efficacy with minimal collateral damage to gut flora and low resistance rates 3.
Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days remains first-line therapy only when local resistance rates are below 20% 1, 2. Rising resistance rates, particularly outside the United States, have necessitated this restriction 1. Check your local antibiogram before prescribing empirically 2.
Fosfomycin trometamol 3 g as a single dose is an appropriate first-line option, particularly convenient for patient adherence 1, 2, 3.
Agents to Avoid or Reserve
Fluoroquinolones (ciprofloxacin, levofloxacin) should NOT be used for uncomplicated cystitis despite their high efficacy in 3-day regimens, because they have significant propensity for collateral damage and serious adverse effects affecting tendons, muscles, joints, nerves, and the central nervous system 1. Reserve these agents for more serious infections like pyelonephritis or when resistant organisms are documented 1.
Amoxicillin or ampicillin should never be used empirically due to poor efficacy and very high worldwide resistance rates 1.
β-lactam agents (amoxicillin-clavulanate, cefdinir, cefaclor, cefpodoxime-proxetil) have inferior efficacy compared to first-line agents and more adverse effects, making them second-line choices only when first-line agents cannot be used 1, 3.
Treatment Duration
Treat for the shortest effective duration—generally no longer than 7 days 1, 2. The specific durations are:
- Nitrofurantoin: 5 days 1, 2
- Trimethoprim-sulfamethoxazole: 3 days 1, 2, 4
- Fosfomycin: single dose 1, 2
- β-lactams (if used): 3-7 days 1
Single-dose regimens other than fosfomycin show higher rates of bacteriological persistence and are not recommended 2.
Special Populations
For men with uncomplicated UTI, use trimethoprim-sulfamethoxazole 160/800 mg twice daily for 7 days (longer than in women) 2. Limited evidence supports 7-14 days of therapy for acute UTI in men 1, 3.
For women with diabetes but no voiding abnormalities, treat similarly to women without diabetes using the same first-line agents and durations 1, 3.
Pyelonephritis (Upper UTI)
For uncomplicated pyelonephritis requiring oral therapy:
- Ciprofloxacin 500-750 mg twice daily for 5-7 days 1, 2
- Levofloxacin 750 mg once daily for 5 days 1, 2
- Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 14 days (if susceptible) 1, 2
Do NOT use nitrofurantoin, fosfomycin, or pivmecillinam for pyelonephritis due to insufficient tissue penetration and lack of efficacy data for upper tract infections 2.
For severe pyelonephritis, use ceftriaxone or cefotaxime, with amikacin as an alternative 1.
Critical Clinical Pitfalls
Always check local antibiograms before prescribing empiric therapy, as resistance patterns vary significantly by geography 2, 5.
Obtain urine culture before treatment in patients with recurrent UTIs, suspected pyelonephritis, symptoms not resolving within 4 weeks, atypical symptoms, or pregnancy 2.
Do not treat asymptomatic bacteriuria except in pregnant women or before invasive urinary procedures 2.
Avoid fluoroquinolones for simple cystitis despite their effectiveness—reserve them for pyelonephritis or documented resistant organisms to minimize collateral damage and serious adverse effects 1.