How do I treat a patient with a urinary tract infection?

Treatment of Urinary Tract Infections

For urinary tract infections, first-line treatment should be nitrofurantoin, trimethoprim-sulfamethoxazole (TMP-SMX), or fosfomycin, with selection guided by local antibiogram patterns and patient-specific factors. 1, 2

Diagnostic Approach

• Obtain urinalysis and urine culture before initiating treatment
• Document positive urine cultures associated with symptomatic episodes
• Consider obtaining catheterized specimen if initial sample is suspect for contamination
• Cystoscopy and upper tract imaging are not routinely needed for uncomplicated UTIs

Treatment Algorithm

First-Line Therapy for Uncomplicated UTIs

1. Nitrofurantoin (100 mg twice daily for 5 days)

   • Highly effective against E. coli
   • Low resistance rates
   • Minimal impact on gut flora
   • Contraindicated if CrCl <30 mL/min

2. Trimethoprim-sulfamethoxazole (TMP-SMX) (160/800 mg twice daily for 3 days)

   • Cost-effective option
   • Only use if local resistance is <20%
   • Avoid in patients with sulfa allergies

3. Fosfomycin (3 g single dose)

   • Convenient single-dose administration
   • Good option when adherence is a concern
   • Effective against many resistant organisms

Alternative Therapy

• Cephalexin (500 mg four times daily for 5-7 days)
• Amoxicillin-clavulanate (875/125 mg every 12 hours) 3
  • Effective for complicated UTIs
  • Consider when first-line agents cannot be used

Treatment Duration

• Uncomplicated UTI: 3-5 days
• Complicated UTI: 7-14 days (generally no longer than 7 days) 1, 2

Special Considerations

Recurrent UTIs

• Document positive cultures with symptomatic episodes
• Consider patient-initiated treatment (self-start) while awaiting cultures 1
• Prophylaxis options:
  • TMP-SMX (40/200 mg once daily or three times weekly)
  • Nitrofurantoin (50-100 mg daily)
  • Methenamine (1 g twice daily) as a non-antibiotic option

Resistant Organisms

• For cultures resistant to oral antibiotics, use culture-directed parenteral antibiotics for as short a course as reasonable 1
• Adjust therapy when culture results return to ensure effective treatment

Renal Impairment

• Avoid nitrofurantoin if CrCl <30 mL/min
• Adjust dosages for other antibiotics based on renal function

Important Caveats

• Avoid fluoroquinolones as first-line therapy due to high risk of adverse effects and increasing resistance 2, 4, 5
• Do not treat asymptomatic bacteriuria except in pregnant women and patients undergoing urologic procedures 2
• Use shortest effective duration of antibiotics to reduce risk of resistance development 1, 2
• Consider local antibiogram patterns when selecting empiric therapy 1, 2
• Obtain cultures before starting antibiotics to guide appropriate therapy 1
• Pain relief with NSAIDs can be considered while awaiting culture results in mild cases 6

The evidence strongly supports using nitrofurantoin, TMP-SMX, or fosfomycin as first-line agents for uncomplicated UTIs, with treatment duration of 3-5 days for uncomplicated infections and up to 7 days for complicated infections. Randomized controlled trials have demonstrated the efficacy of nitrofurantoin over placebo for both symptomatic improvement and bacteriological cure 7.