First-Line Antibiotic for Uncomplicated UTI
For uncomplicated urinary tract infections in women, nitrofurantoin (100 mg twice daily for 5 days) is the preferred first-line antibiotic, followed by fosfomycin (3g single dose) or pivmecillinam (400 mg three times daily for 3-5 days) where available. 1, 2
Recommended First-Line Options
The European Association of Urology and Infectious Diseases Society of America prioritize three agents based on minimal resistance patterns and preservation of broader-spectrum antibiotics for more serious infections:
Nitrofurantoin monohydrate/macrocrystals (100 mg twice daily for 5 days) is the most preferred option due to minimal resistance patterns and limited collateral damage to normal flora 2, 3
Fosfomycin trometamol (3g single dose) offers convenient single-dose therapy, though it may have slightly inferior efficacy compared to multi-day regimens 1, 2, 3
Pivmecillinam (400 mg three times daily for 3-5 days) is recommended primarily in European countries where it is available 1, 2
Alternative Options Based on Local Resistance
Trimethoprim-sulfamethoxazole (160/800 mg twice daily for 3 days) can be used only if local E. coli resistance rates are below 20% or if the specific isolate is known to be susceptible 1, 2, 4
Rising resistance rates globally have challenged trimethoprim-sulfamethoxazole's position as automatic first-line therapy, despite its historical use 1, 4
Trimethoprim alone (200 mg twice daily for 5 days) is an alternative, but should not be used in the first trimester of pregnancy 1
Antibiotics to Avoid for Empiric Treatment
Amoxicillin or ampicillin should never be used empirically due to poor efficacy and very high worldwide prevalence of antimicrobial resistance 1, 2
Fluoroquinolones (ciprofloxacin, levofloxacin) should be reserved for situations where first-line agents cannot be used, despite their high efficacy, to prevent promoting resistance to these important agents needed for more serious infections 2, 4
β-lactams (including amoxicillin-clavulanate, cefadroxil, cefdinir) generally have inferior efficacy and more adverse effects compared to other UTI antimicrobials 1, 2, 4
Special Population Considerations
Men with UTI
- Male UTIs are considered complicated and require 7-14 days of treatment rather than the shorter courses used in women 1, 3
- First-line options include trimethoprim-sulfamethoxazole (160/800 mg twice daily for 7-14 days) or fluoroquinolones (ciprofloxacin 500mg twice daily for 7 days) if local resistance is less than 10% 1, 3
Patients with Renal Impairment
- For trimethoprim-sulfamethoxazole: standard dosing for CrCl >30 mL/min; reduce to half-dose for CrCl 15-30 mL/min; consider alternative agent for CrCl <15 mL/min 1
Common Pitfalls to Avoid
Do not prescribe trimethoprim-sulfamethoxazole empirically without knowledge of local resistance patterns - this is only appropriate when local resistance is documented to be <20% 2, 4
Do not use fluoroquinolones as first-line therapy despite their excellent efficacy, as this promotes resistance to agents needed for pyelonephritis and other serious infections 2
Do not use 3-day regimens in men - they require 7-14 days of therapy regardless of the antibiotic chosen 1, 3
Do not fail to obtain urine culture in cases of suspected pyelonephritis, symptoms that don't resolve within 4 weeks, atypical symptoms, pregnant women, or treatment failure 1, 2
When to Obtain Urine Culture
- Urine culture is not routinely needed for straightforward uncomplicated cystitis in women 2, 3
- Obtain culture for: recurrent infection, treatment failure, history of resistant isolates, atypical presentation, male patients, or symptoms that don't resolve by end of treatment or recur within 2 weeks 1, 2, 3