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

Treatment of Urinary Tract Infections (UTIs)

For uncomplicated UTIs in non-pregnant adults, first-line oral therapy should be nitrofurantoin 100 mg twice daily for 5 days, trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 3 days, or fosfomycin 3g single dose, with nitrofurantoin having the strongest evidence for clinical resolution. 1

First-Line Treatment Options for Uncomplicated UTIs

• Nitrofurantoin: 100 mg twice daily for 5 days (high strength of evidence) 1, 2

  • Achieves 70% clinical resolution rate 2
  • Maintains good activity against E. coli and other common uropathogens 3
  • Superior to fosfomycin in clinical and microbiological resolution 2

• Trimethoprim-sulfamethoxazole (TMP-SMX): 160/800 mg twice daily for 3 days 1, 4

  • Only use if local resistance is <20% 1
  • FDA-approved for UTIs caused by E. coli, Klebsiella, Enterobacter, Morganella morganii, and Proteus species 4

• Fosfomycin: 3g single dose (moderate strength of evidence) 1

  • Convenient single-dose regimen
  • Less effective than nitrofurantoin (58% vs 70% clinical resolution) 2

Second-Line Treatment Options

• Pivmecillinam: 400 mg twice daily for 5 days (moderate evidence) 1, 5
• Amoxicillin-clavulanate: 500/125 mg twice daily for 3-7 days (moderate evidence) 1
• Cephalexin: 500 mg four times daily for 5-7 days (moderate evidence) 1

Treatment for Complicated UTIs

Pyelonephritis

• Oral ciprofloxacin: 500 mg twice daily for 7 days (if fluoroquinolone resistance <10%) 1
• Severe cases: Parenteral ceftriaxone or cefotaxime initially 1

Special Populations

Pregnant Women

• First-line: Nitrofurantoin or Cephalexin 1
• Avoid: TMP-SMX in first and third trimesters (risk of neural tube defects and kernicterus) 1
• Contraindicated: Tetracyclines (potential fetal harm) 1

Patients with Renal Impairment

Levofloxacin dosing adjustment based on creatinine clearance:

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

Diagnostic Approach

1. Before starting antibiotics: Perform urinalysis and urine culture to confirm infection and guide therapy 1
2. Evaluate for complicated UTI: Check for fever, flank pain, nausea/vomiting 1
3. Imaging: Consider renal and bladder ultrasound if signs of upper tract involvement, failed therapy, recurrent UTIs, or suspected obstruction/stones 1

Antibiotic Resistance Considerations

• E. coli is the most common pathogen (39-81% of cases) 1
• Significant resistance to fluoroquinolones (39.9%) and TMP-SMX (46.6%) exists 1
• E. coli shows higher sensitivity to fosfomycin (95.5%), nitrofurantoin (85.5%), and cefuroxime (82.3%) 1
• Important: Check local resistance patterns before prescribing empiric therapy 1, 6, 5

Prevention of Recurrent UTIs

• Increase fluid intake to 2-3 liters daily 1
• Urinate frequently and after sexual intercourse 1
• For postmenopausal women: Consider vaginal estrogens 1
• For recurrent UTIs (≥3 episodes/year or 2 episodes in 6 months): Consider prophylactic antibiotics 1

Common Pitfalls to Avoid

1. Don't treat asymptomatic bacteriuria except in pregnant women or before urological procedures 1
2. Don't use fluoroquinolones as first-line due to resistance concerns and side effects 1
3. Don't forget to collect urine culture before starting antibiotics 1
4. Don't overlook local resistance patterns when selecting empiric therapy 1
5. Don't use TMP-SMX empirically if local resistance exceeds 20% 1, 6