Recommended Antibiotic Regimen for Uncomplicated UTI
For uncomplicated urinary tract infections in women, prescribe nitrofurantoin 100 mg twice daily for 5 days as first-line therapy. 1
First-Line Treatment Options
The following antibiotics are recommended as first-line therapy, with selection based on local resistance patterns and patient factors:
Nitrofurantoin 100 mg twice daily for 5 days - This is the preferred first-line agent recommended by both IDSA and AUA guidelines 1. It maintains excellent activity against common uropathogens despite decades of use 2, 3 and causes minimal collateral damage to normal flora 4.
Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 3 days - Use only if local E. coli resistance rates are below 20% 4, 1, 5. Rising resistance has made this less reliable in many regions 1.
Fosfomycin 3 g single oral dose - Convenient single-dose option 1, 6, though may have slightly inferior efficacy compared to nitrofurantoin 1. Mix with water before ingesting; never take in dry form 6.
Trimethoprim 100 mg twice daily for 3 days - Alternative when TMP-SMX cannot be used 7.
Treatment Duration
Keep antibiotic courses as short as reasonable, generally no longer than 7 days 4. The standard 5-day course for nitrofurantoin balances efficacy with minimizing adverse effects 1. Three-day regimens are appropriate for TMP-SMX and trimethoprim 4, 7.
When to Avoid First-Line Agents
Fluoroquinolones (ciprofloxacin, levofloxacin) should be reserved for more invasive infections 1, 8 due to serious FDA warnings about tendon, muscle, joint, nerve, and CNS toxicity 1. Despite high efficacy, their use causes significant collateral damage and promotes resistance 1.
β-lactam agents (amoxicillin-clavulanate, cefdinir, cefaclor, cefpodoxime) have inferior efficacy 1, 8 and should only be used when first-line agents cannot be tolerated. Amoxicillin or ampicillin alone should never be used empirically due to poor efficacy and high resistance 1.
Diagnostic Approach
For initial uncomplicated UTI in women, diagnosis can be made clinically without urine culture 1, 7. Self-diagnosis with typical symptoms (frequency, urgency, dysuria, nocturia, suprapubic pain) without vaginal discharge is sufficiently accurate 7.
Obtain urine culture and sensitivity before treatment in these situations:
- Recurrent UTIs (each symptomatic episode) 4
- Treatment failure 4, 7
- History of resistant organisms 4, 7
- Atypical presentation 4, 7
- Men with UTI symptoms 7
- Adults ≥65 years old 7
Special Populations
Men with uncomplicated UTI: Always obtain urine culture and treat for 7 days with trimethoprim, TMP-SMX, or nitrofurantoin 7. Consider urethritis and prostatitis as alternative diagnoses 7.
Recurrent UTIs: Continue obtaining cultures with each symptomatic episode to guide therapy and track resistance patterns 4. Do not treat asymptomatic bacteriuria 4, 1 and omit surveillance urine testing in asymptomatic patients 4, 1.
Resistant organisms: For VRE causing uncomplicated UTI, use nitrofurantoin 100 mg every 6 hours 4. For carbapenem-resistant Enterobacteriaceae, single-dose aminoglycoside may be considered 4.
Important Contraindications
Do not use nitrofurantoin for:
- Upper UTIs or pyelonephritis (inadequate tissue concentrations) 1
- Infants under 4 months (risk of hemolytic anemia) 1
- Any degree of renal impairment 2
- Last trimester of pregnancy 2
Common Pitfalls to Avoid
- Do not routinely prescribe fluoroquinolones for simple cystitis - reserve them for complicated infections despite their high efficacy 1, 8
- Do not treat asymptomatic bacteriuria except in pregnancy or before invasive urologic procedures 4, 1
- Do not use longer courses than necessary - this increases adverse effects without improving outcomes 4
- Do not order follow-up cultures unless symptoms persist or recur within 2-4 weeks 1