What is the recommended treatment for a 12-year-old girl with an uncomplicated urinary tract infection (UTI)?

Treatment of Uncomplicated UTI in a 12-Year-Old Girl

For a 12-year-old girl with an uncomplicated urinary tract infection, prescribe nitrofurantoin 100 mg twice daily for 5 days as first-line therapy. 1

First-Line Antibiotic Options

The following antibiotics are recommended as first-line treatment, with nitrofurantoin being the preferred choice due to minimal resistance patterns and low collateral damage to normal flora:

• Nitrofurantoin monohydrate/macrocrystals: 100 mg twice daily for 5 days 1, 2

  • This is the optimal choice with proven efficacy in pediatric patients and minimal resistance 3, 4
  • Specifically studied and effective in girls as young as 2 years with lower UTI 4

• Trimethoprim-sulfamethoxazole: 160/800 mg (one double-strength tablet) twice daily for 3 days 1, 5

  • Only use if local resistance rates are <20% or if the organism is known to be susceptible 1
  • FDA-approved dosing for children ≥2 months: 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours in two divided doses 5
  • For a 12-year-old, the adult dose of one DS tablet twice daily is appropriate 6, 5

• Fosfomycin trometamol: 3 g single dose 1

  • Convenient single-dose regimen but slightly lower efficacy than nitrofurantoin 1

Important Clinical Considerations

Do not routinely obtain urine culture unless there are specific indications such as: 1, 2

• Suspected pyelonephritis (fever, flank pain, systemic symptoms)
• Symptoms persist or recur within 4 weeks after treatment
• History of resistant organisms
• Recurrent infections (≥3 UTIs per year or ≥2 UTIs in 6 months) 1

Avoid fluoroquinolones in this age group unless absolutely necessary, as pediatric infectious disease consultation is recommended prior to their use in children 6

Treatment Duration Rationale

Three to five-day regimens are superior to single-dose therapy for uncomplicated UTIs in all age groups, with 3-day trimethoprim-sulfamethoxazole or 5-day nitrofurantoin showing optimal efficacy 7, 4. The shorter courses reduce adverse effects while maintaining therapeutic effectiveness 2, 4.

Common Pitfalls to Avoid

• Do not treat asymptomatic bacteriuria - screening and treatment increase antimicrobial resistance without clinical benefit 1
• Do not use nitrofurantoin if pyelonephritis is suspected - it does not achieve adequate tissue levels for upper tract infections 6, 1
• Verify local resistance patterns before prescribing trimethoprim-sulfamethoxazole, as resistance rates >20% make it inappropriate for empiric therapy 1