What are the recommended antibiotics for treating urinary tract infections (UTIs)?

Recommended Antibiotics for Urinary Tract Infections (UTIs)

For uncomplicated UTIs in adults, first-line treatment options include nitrofurantoin, fosfomycin, or trimethoprim-sulfamethoxazole, with selection based on local resistance patterns and patient factors. 1, 2, 3

First-Line Treatment Options

• Nitrofurantoin:

  • Dosage: 100 mg three times daily for 5 days
  • Advantages: High efficacy against common uropathogens, low resistance rates
  • Contraindications: Renal impairment (CrCl <30 mL/min), G6PD deficiency

• Fosfomycin trometamol:

  • Dosage: Single 3 g dose
  • Advantages: Convenient single-dose regimen, effective against multi-drug resistant pathogens
  • Note: Clinical resolution rates may be lower compared to nitrofurantoin (58% vs 70%) 4

• Trimethoprim-sulfamethoxazole (TMP-SMX):

  • Dosage: 1 double-strength tablet (160 mg/800 mg) every 12 hours for 10-14 days 2
  • Caution: Should be avoided in areas with >20% resistance rates

Second-Line Treatment Options

• Fluoroquinolones (e.g., ciprofloxacin, levofloxacin):

  • Ciprofloxacin: 500 mg twice daily or 1000 mg extended-release daily
  • Levofloxacin: 750 mg daily for 5-7 days 1
  • Caution: Reserve for complicated UTIs due to resistance concerns and adverse effects
  • Adjust dosing based on renal function 1

• Oral cephalosporins (e.g., cephalexin, cefixime)

• Beta-lactams (e.g., amoxicillin-clavulanate)

Treatment Algorithm Based on UTI Classification

Uncomplicated Lower UTI (Cystitis)

1. First-line: Nitrofurantoin 100 mg TID for 5 days OR fosfomycin 3 g single dose
2. Alternative: TMP-SMX 1 DS tablet BID for 10-14 days (if local resistance <20%)
3. Second-line: Fluoroquinolones or beta-lactams

Complicated UTI or Pyelonephritis

1. First-line: Fluoroquinolones (if local resistance <10%)
   • Ciprofloxacin 500 mg BID or levofloxacin 750 mg daily for 5-7 days 1
2. Alternative: TMP-SMX (if susceptibility confirmed)
3. For multi-drug resistant infections: Consider meropenem 1g IV q8h 1

UTI with Penicillin Allergy

• For patients with penicillin allergy, fluoroquinolones are recommended first-line options
• In cases of multi-drug resistance, fosfomycin is considered most appropriate 1

Special Considerations

• Renal Impairment: Adjust dosing based on creatinine clearance:

  Creatinine Clearance	Recommended Dosing
  ≥50 mL/min	Standard dosing
  26-49 mL/min	500 mg once daily (levofloxacin)
  10-25 mL/min	250 mg once daily (levofloxacin)
  <15 mL/min	TMP-SMX not recommended 1, 2

• Pregnant Women: Avoid TMP-SMX in first trimester and near term; nitrofurantoin or beta-lactams preferred

• Elderly Patients: Monitor for adverse effects, particularly with fluoroquinolones (risk of tendinopathy, CNS effects) 1

Antibiotic Stewardship Principles

• Obtain urine culture before starting antibiotics in complicated cases
• Reserve carbapenems for confirmed multi-drug resistant infections 1
• Consider local antibiogram data when selecting empiric therapy
• Avoid treating asymptomatic bacteriuria except in pregnant women or before urological procedures 1

Non-Antibiotic Measures for Prevention

• Increased fluid intake
• Frequent urination
• Vaginal estrogens for postmenopausal women (moderate evidence)
• Cranberry products (modest effect, low evidence) 1