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

Treatment of Urinary Tract Infection in Teenagers

For teenagers with uncomplicated UTI, treat with oral antibiotics for 3 days for cystitis or 7-14 days for pyelonephritis, using trimethoprim/sulfamethoxazole, nitrofurantoin, or a cephalosporin based on local resistance patterns. 1

Antibiotic Selection and Duration

For Cystitis (Lower UTI)

• First-line oral agents include:

  • Trimethoprim/sulfamethoxazole for 3 days 2, 3
  • Nitrofurantoin for 5 days 3
  • Trimethoprim alone for 3 days 3
  • Cephalexin 50-100 mg/kg per day divided in 4 doses 1

• Treatment duration should be 3 days for uncomplicated lower tract infections 2

For Pyelonephritis (Upper UTI)

• Treatment duration should be 7-14 days 1

• Oral options include:

  • Cefixime 8 mg/kg per day in 1 dose 1
  • Cefpodoxime 10 mg/kg per day in 2 doses 1
  • Amoxicillin-clavulanate 20-40 mg/kg per day in 3 doses 1
  • Trimethoprim/sulfamethoxazole (6-12 mg/kg trimethoprim component per day in 2 doses) 1

• For severe illness or inability to tolerate oral intake, use parenteral therapy:

  • Ceftriaxone 75 mg/kg every 24 hours 1
  • Cefotaxime 150 mg/kg per day divided every 6-8 hours 1
  • Switch to oral therapy once clinical improvement occurs (typically 24-48 hours) 1

Key Treatment Principles

Route of Administration

• Oral and parenteral routes are equally efficacious 1
• Base the choice on practical considerations: use parenteral therapy only if the patient appears toxic or cannot retain oral medications 1
• Most teenagers can be treated entirely with oral antibiotics 1

Antibiotic Selection Strategy

• Base empiric choice on local antimicrobial sensitivity patterns 1
• Adjust therapy according to culture and susceptibility results once available 1
• Avoid nitrofurantoin for febrile UTI/pyelonephritis as it does not achieve adequate blood concentrations 1

Important Clinical Considerations

Sexual Activity Assessment

• All adolescents with UTI should be questioned about sexual activity 2
• UTIs in teenagers are markers for sexual activity, unlike younger children where they indicate anatomic abnormalities 2
• Screen for sexually transmitted diseases and provide counseling about safe sexual practices 2

Follow-Up

• Clinical improvement (including fever resolution) should occur within 48-72 hours 1
• If no improvement by 72 hours, reassess diagnosis and consider imaging or treatment change 1
• Routine follow-up is not necessary for uncomplicated first UTI in teenagers unless recurrence occurs 1

Imaging Recommendations

• Renal ultrasound is NOT routinely indicated for first uncomplicated UTI in teenagers over 6 years of age 1
• After age 6, vesicoureteral reflux is less common and routine imaging provides minimal benefit 1
• Consider imaging only for recurrent infections, complicated UTI, or atypical presentation 1

Common Pitfalls to Avoid

• Do not use bag-collected urine specimens for culture in any age group due to high contamination rates 1, 4
• Do not treat asymptomatic bacteriuria as this may be harmful and promotes antibiotic resistance 1
• Do not prescribe prophylactic antibiotics after first UTI; reserve for high-risk patients with recurrent infections 1, 5
• Do not order voiding cystourethrogram (VCUG) after first uncomplicated UTI in teenagers 1