Treatment of Pediatric Urinary Tract Infection
Immediate Diagnostic Requirements Before Starting Antibiotics
Obtain a urine culture by catheterization or suprapubic aspiration in non-toilet-trained children before initiating any antimicrobial therapy—this is the only opportunity for definitive diagnosis and susceptibility testing. 1 Bag-collected specimens have false-positive rates of 12–83% and should never be used for culture. 1 For toilet-trained children, a midstream clean-catch specimen is acceptable. 1
Diagnosis requires both pyuria (≥10 WBC/HPF or positive leukocyte esterase) and ≥50,000 CFU/mL of a single uropathogen from a properly collected specimen. 1, 2 Urinalysis alone is insufficient—culture confirmation is mandatory. 2
Age-Based Treatment Algorithm
Neonates (<28 days old)
- Hospitalize immediately and administer parenteral ampicillin + aminoglycoside (gentamicin) or third-generation cephalosporin (ceftriaxone 50 mg/kg IV/IM every 24 hours or cefotaxime 150 mg/kg/day divided every 6–8 hours) for a total of 14 days. 1, 3 After 3–4 days of IV therapy with clinical improvement, transition to oral antibiotics to complete the 14-day course. 3
Infants 28 days to 3 months
- If toxic-appearing or unable to retain oral intake: Hospitalize and give parenteral third-generation cephalosporin (ceftriaxone 50 mg/kg IV/IM every 24 hours) or gentamicin until afebrile for 24 hours, then complete 14 days total with oral antibiotics. 1, 3
- If well-appearing and able to tolerate oral intake: Outpatient management with daily parenteral ceftriaxone or gentamicin until afebrile for 24 hours, then complete 14 days with oral antibiotics. 3
Children ≥3 months with febrile UTI/pyelonephritis
Oral and parenteral routes are equally efficacious when the child can tolerate oral medications—only ~1% require parenteral therapy. 1
First-line oral options (7–14 days, most commonly 10 days):
- Amoxicillin-clavulanate 20–40 mg/kg/day divided into 3 doses 1, 2
- Cefixime 8 mg/kg once daily 1
- Cephalexin 50–100 mg/kg/day divided every 6 hours 1
- Trimethoprim-sulfamethoxazole only if local E. coli resistance is <10% 1
Parenteral options (for toxic appearance, vomiting, or uncertain compliance):
- Ceftriaxone 50–75 mg/kg IV/IM every 24 hours (maximum 2 g) 1, 2
- Cefotaxime 150 mg/kg/day divided every 6–8 hours 2
- Gentamicin (dose adjusted for age/weight) 3
Do not use nitrofurantoin for febrile UTI—it does not achieve adequate serum/parenchymal concentrations to treat pyelonephritis. 1
Children with uncomplicated cystitis (non-febrile lower UTI)
- First-line oral therapy for 5–7 days (moderate-to-severe symptoms) or 3–5 days (mild symptoms): 1
- Nitrofurantoin is a second-line option for uncomplicated cystitis only. 1
Critical Treatment Principles
- Initiate treatment within 48 hours of fever onset to reduce renal scarring risk by >50%. 1 Early antimicrobial therapy limits renal damage better than delayed treatment. 2
- Adjust antibiotics based on culture and sensitivity results when available—local resistance patterns vary widely. 1, 2
- Treatment courses shorter than 7 days are inferior for febrile UTI and must be avoided. 1 For uncomplicated cystitis, 3–5 days may be sufficient in children >2 years. 1
- Fluoroquinolones should be avoided in children due to musculoskeletal safety concerns; reserve them only for severe infections where benefits outweigh risks. 1
Follow-Up Imaging After First Febrile UTI
- Obtain renal and bladder ultrasound (RBUS) in all children <2 years with first febrile UTI to detect anatomic abnormalities (hydronephrosis, scarring, obstruction). 1, 2 Ideally perform within 48 hours of starting therapy. 1
- Voiding cystourethrography (VCUG) is NOT routinely indicated after the first UTI. 1, 2 Perform VCUG only if:
Clinical Follow-Up Strategy
- Reassess within 1–2 days to confirm fever resolution and clinical improvement. 1 If fever persists beyond 48–72 hours, evaluate for antibiotic resistance, obstruction, or abscess formation. 1
- Instruct parents to seek prompt medical evaluation (ideally within 48 hours) for any future febrile illness to enable early detection of recurrent UTI. 1, 2
- No routine follow-up urine culture is needed after successful treatment of uncomplicated first UTI. 1
Common Pitfalls to Avoid
- Do not delay antibiotic treatment while awaiting culture results in febrile children—early treatment (<48 hours) reduces renal scarring risk. 1
- Do not use bag-collected urine for culture—false-positive rates approach 85%, leading to overtreatment. 1
- Do not prescribe treatment courses shorter than 7 days for febrile UTI. 1
- Do not use nitrofurantoin for any child with fever and suspected pyelonephritis. 1
- Do not omit obtaining a urine culture before starting antibiotics—the initial culture is the only opportunity for definitive diagnosis. 1
- Do not order VCUG routinely after a first UTI; reserve it for the specific indications listed above. 1
- Do not treat asymptomatic bacteriuria—it offers no benefit and promotes resistance. 1
Special Populations
- Uncircumcised boys <6 months: Higher contamination risk (~43%); suprapubic aspiration should be considered for specimen collection. 1
- Children with bowel/bladder dysfunction (constipation, dysfunctional voiding): Aggressive treatment of constipation (disimpaction followed by maintenance regimen) and timed voiding schedules are essential to prevent recurrence. 1
- Recurrent UTI (≥2 episodes in 6 months or ≥3 in 12 months): Each episode must be documented with culture to monitor resistance patterns; consider VCUG after the second febrile UTI. 1
Long-Term Outcomes
Renal scarring occurs in approximately 15% of children after a first febrile UTI and can lead to hypertension in ~5% and chronic kidney disease in 3.5% of end-stage renal disease cases. 1 The risk of scarring increases with recurrent infections. 2 Early antimicrobial therapy initiated within 48 hours may decrease the risk of scarring. 1, 2