What are the recommended antibiotics for symptomatic Urinary Tract Infections (UTIs)?

Recommended Antibiotics for Symptomatic Urinary Tract Infections

For uncomplicated UTIs in non-pregnant adults, first-line antibiotics are nitrofurantoin 100mg twice daily for 5 days, trimethoprim-sulfamethoxazole 160/800mg twice daily for 3 days, or fosfomycin 3g single dose. 1

First-Line Treatment Options for Uncomplicated UTIs

Non-Pregnant Adults

• Nitrofurantoin (high strength of evidence)

  • Dosage: 100mg twice daily
  • Duration: 5 days
  • Advantages: High sensitivity against E. coli (85.5%)

• Trimethoprim-sulfamethoxazole (TMP-SMX)

  • Dosage: 160/800mg twice daily
  • Duration: 3 days
  • Note: Consider local resistance patterns (E. coli resistance ~46.6%)

• Fosfomycin (moderate strength of evidence)

  • Dosage: 3g single dose
  • Advantages: High sensitivity against E. coli (95.5%)

Special Populations and Considerations

Pregnant Women

• Preferred options:
  • Nitrofurantoin
  • Cephalexin (500mg four times daily for 5-7 days)
• Avoid:
  • TMP-SMX in first and third trimesters (risk of neural tube defects and kernicterus)
  • Tetracyclines (contraindicated throughout pregnancy)

Men

• All UTIs in men are considered complicated and require longer treatment
• Duration: 14-day course of antibiotics
• Options: Same antibiotics as for women but with extended duration

Patients with Renal Impairment

• Levofloxacin dosing adjustment:
  • CrCl ≥50 mL/min: 750mg once daily for 5 days
  • CrCl 20-49 mL/min: 500mg once daily
  • CrCl 10-19 mL/min: 250mg once daily
  • Hemodialysis: 250-500mg every 48 hours (post-HD on dialysis days) 1

Second-Line Options

• Pivmecillinam: 400mg twice daily for 5 days
• Amoxicillin-clavulanate: 500/125mg twice daily for 3-7 days
• Cephalexin: 500mg four times daily for 5-7 days
• Fluoroquinolones (reserve for more invasive infections):
  • Ciprofloxacin: 500-750mg twice daily for 7 days
  • Levofloxacin: 750mg once daily for 5 days 1, 2

Antibiotic Selection Based on Resistance Patterns

When to Obtain Urine Culture

• Recurrent infections
• Treatment failure
• History of resistant isolates
• Atypical presentation
• All cases in men
• Older adults (≥65 years) 1, 3

Considerations for Resistant Organisms

• E. coli is the most common pathogen (39-81% of cases)
• Local antibiotic resistance patterns should guide empiric therapy
• For ESBL-producing organisms, options include nitrofurantoin, fosfomycin, and carbapenems 2, 4

Prevention of Recurrent UTIs

• Increased fluid intake
• Vaginal estrogens for postmenopausal women
• Consider prophylactic strategies:
  • Post-coital antibiotics
  • Daily low-dose antibiotic prophylaxis with nitrofurantoin
  • Non-antibiotic alternatives: methenamine hippurate, cranberry products 1

Common Pitfalls to Avoid

1. Treating asymptomatic bacteriuria (except in pregnancy or before urological procedures)
2. Using fluoroquinolones as first-line therapy due to increasing resistance and risk of adverse effects
3. Inadequate treatment duration for men or complicated UTIs
4. Failing to adjust antibiotics based on culture results when available
5. Not changing indwelling catheters prior to collecting urine samples for culture 1

Remember that antibiotic selection should be guided by local resistance patterns, and treatment should be adjusted based on culture results when available. The goal is to achieve clinical cure while minimizing the risk of developing antibiotic resistance.