What is the recommended treatment for a 14-year-old female with a urinary tract infection (UTI)?

Treatment of UTI in a 14-Year-Old Female

For a 14-year-old female with an uncomplicated UTI, treat with nitrofurantoin 100 mg twice daily for 5 days as first-line therapy, or alternatively trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days if local resistance rates are below 20%. 1

First-Line Antibiotic Options

The following agents are recommended based on current guidelines, prioritizing efficacy and minimizing antimicrobial resistance:

• Nitrofurantoin: 100 mg twice daily for 5 days is the preferred first-line agent due to high efficacy against common uropathogens and low resistance rates 1, 2, 3

• Trimethoprim-sulfamethoxazole (TMP-SMX): 160/800 mg twice daily for 3 days is appropriate if local E. coli resistance is <20% 1, 2

  • According to FDA labeling, the pediatric dose for UTI is 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim per 24 hours, given in two divided doses every 12 hours for 10 days 4
  • However, guidelines support shorter 3-day courses for uncomplicated cystitis in adolescents 1

• Fosfomycin trometamol: 3 g single dose is another first-line option, though specifically recommended for women with uncomplicated cystitis 1, 2, 3

Treatment Duration

Keep antibiotic courses as short as reasonable, generally no longer than 7 days for uncomplicated UTI. 1 For simple cystitis, 3-5 day courses are adequate with first-line agents 1, 2

Diagnostic Considerations Before Treatment

While adolescents can often be treated empirically, consider the following:

• Obtain urine culture and sensitivity if this is a recurrent UTI (≥3 UTIs/year or 2 UTIs in 6 months) before initiating treatment 1

• Confirm symptomatic infection with dysuria, frequency, urgency, or suprapubic pain—do not treat asymptomatic bacteriuria 1

• Urinalysis with nitrite dipstick and leukocyte esterase can support diagnosis without culture in straightforward cases 5, 2

Agents to Avoid or Use as Second-Line

• Fluoroquinolones should be reserved for more invasive infections, not used as first-line for simple cystitis due to concerns about resistance and side effects 1, 2, 6

• β-lactam agents (amoxicillin-clavulanate, cephalosporins) are less effective as empirical first-line therapy compared to nitrofurantoin or TMP-SMX 2

Important Caveats

• Do not perform extensive workup (cystoscopy, imaging) in young females with uncomplicated UTI unless there are risk factors for complicated infection 1

• Avoid treating asymptomatic bacteriuria—surveillance urine testing should be omitted in asymptomatic patients 1

• Check local antibiogram patterns to guide empiric therapy, as resistance rates vary by community 1, 6

• Nitrofurantoin contraindications: Avoid if creatinine clearance <30 mL/min or if there is concern for pyelonephritis, as it does not achieve adequate tissue levels in the kidney 1

If Treatment Fails

If symptoms persist after 2-3 days or recur shortly after completion:

• Obtain urine culture and susceptibility testing to guide retreatment 1

• Assume the organism is not susceptible to the original agent and use a different antibiotic class for 7 days 1

• Consider complicated UTI if there are repeated failures, prompting evaluation for anatomic abnormalities or other risk factors 1