What is the recommended treatment for a urinary tract infection (UTI)?

Treatment of Urinary Tract Infections

For uncomplicated urinary tract infections (UTIs), first-line treatment options are nitrofurantoin 100mg twice daily for 5 days, fosfomycin as a single 3g dose, or trimethoprim-sulfamethoxazole (TMP-SMX) for 3 days if local resistance is below 20%. 1

First-Line Treatment Options for Uncomplicated UTIs

Nitrofurantoin

• Dosage: 100mg twice daily for 5 days
• Advantages: Low resistance rates, effective against most common uropathogens including ESBL-producing E. coli
• Limitations: Not recommended for patients with CrCl <30 mL/min or for upper UTIs

Fosfomycin

• Dosage: Single 3g dose
• Advantages: Convenient single-dose regimen, low resistance rates
• Limitations: Slightly lower efficacy compared to multi-day regimens

Trimethoprim-Sulfamethoxazole (TMP-SMX)

• Dosage: 160/800mg (double strength) twice daily for 3 days
• Advantages: FDA-approved for UTIs due to E. coli, Klebsiella, Enterobacter, Morganella morganii, and Proteus species 2
• Limitations: Should only be used when local resistance rates are <20%

Treatment for Complicated UTIs

For complicated UTIs (including pyelonephritis, UTIs in men, or UTIs with systemic symptoms):

• Levofloxacin: 750mg once daily for 5-7 days (uncomplicated) or 7-10 days (complicated) 1, 3
• Alternative options for complicated UTIs if fluoroquinolones cannot be used:
  • Carbapenems (for severe infections)
  • Ceftazidime-avibactam (for resistant organisms)
  • Parenteral therapy with aminoglycosides 1

Special Considerations

Antimicrobial Resistance

• Local resistance patterns should guide empiric therapy
• Fluoroquinolones should be reserved for complicated UTIs due to increasing resistance and adverse effects 4, 1
• For ESBL-producing organisms, nitrofurantoin remains effective for lower UTIs 1, 5

Catheter-Associated UTIs

• Replace urinary catheter before starting antimicrobial therapy to improve outcomes 1
• Longer treatment duration (7-10 days) is typically required

Recurrent UTIs

• Defined as ≥3 UTIs in 12 months or ≥2 in 6 months 6
• Preventive strategies:
  • Adequate hydration and post-coital voiding
  • Vaginal estrogen for postmenopausal women (reduces UTI risk by 30-50%) 1
  • Methenamine hippurate for women without urinary tract abnormalities 1
  • Antibiotic prophylaxis as last resort due to resistance concerns

Treatment Algorithm

1. Assess for complicated vs. uncomplicated UTI:

   • Uncomplicated: Healthy non-pregnant women with no structural/functional abnormalities
   • Complicated: Men, pregnancy, immunocompromised, structural abnormalities, or systemic symptoms

2. For uncomplicated UTIs:

   • First-line: Nitrofurantoin 100mg BID for 5 days, fosfomycin 3g single dose, or TMP-SMX for 3 days
   • Second-line: Cephalexin, amoxicillin-clavulanate 5

3. For complicated UTIs:

   • Levofloxacin 750mg daily for 7-10 days
   • Consider parenteral therapy for severe infections or resistant organisms

4. Follow-up:

   • Symptoms should improve within 48-72 hours
   • No routine post-treatment cultures needed for uncomplicated UTIs with symptom resolution 1
   • Consider follow-up cultures for complicated cases or treatment failures

Common Pitfalls to Avoid

• Treating asymptomatic bacteriuria: Only treat if pregnant or before urologic procedures 6
• Overuse of fluoroquinolones: Reserve for complicated UTIs due to resistance concerns and adverse effects
• Inadequate treatment duration: Too short courses may lead to treatment failure; too long courses promote resistance
• Ignoring local resistance patterns: Local antibiogram data should guide empiric therapy
• Failure to replace catheters: Always replace urinary catheters before starting antibiotics

By following these evidence-based recommendations, clinicians can effectively treat UTIs while practicing antimicrobial stewardship to limit the development of antibiotic resistance.