What is the recommended treatment for urinary tract infections (UTIs) in children?

Treatment of Urinary Tract Infections in Children

For children aged 2-24 months with febrile UTI, initiate oral antibiotics immediately for 7-14 days using amoxicillin-clavulanate, a cephalosporin, or trimethoprim-sulfamethoxazole based on local resistance patterns, reserving parenteral therapy only for toxic-appearing children or those unable to tolerate oral medications. 1, 2

Diagnostic Requirements Before Treatment

• Obtain urine culture before starting antibiotics—this is non-negotiable for confirming diagnosis and guiding therapy adjustments 2
• For non-toilet-trained children, collect urine by catheterization or suprapubic aspiration; bag specimens should never be used for culture 1, 2
• For toilet-trained children, obtain midstream clean-catch urine after cleaning external genitalia 2, 3
• Diagnosis requires both pyuria (or bacteriuria on urinalysis) and ≥50,000 CFU/mL of a single uropathogen on culture 1

Initial Antibiotic Selection

First-line oral options (choose based on local resistance patterns): 1, 2

• Amoxicillin-clavulanate
• Cephalosporins (e.g., cephalexin for cystitis, cefixime for pyelonephritis)
• Trimethoprim-sulfamethoxazole (if local E. coli resistance <20%)

Parenteral therapy indications: 1, 2

• Toxic appearance
• Unable to retain oral intake
• Uncertain compliance
• Age <3 months (add ampicillin to cover Enterococcus and Listeria) 4

For parenteral therapy: Third-generation cephalosporins (ceftriaxone) or aminoglycosides 2, 4

Treatment Duration

• Febrile UTI/pyelonephritis: 7-14 days total 1, 2
• Uncomplicated cystitis in children >2 years: 3-5 days may be sufficient (though 7-10 days is traditional) 2
• Shorter courses (1-3 days) are inferior for febrile UTIs and should be avoided 2

Critical Medications to Avoid

Never use nitrofurantoin for febrile UTI/pyelonephritis—it does not achieve adequate serum or renal parenchymal concentrations to treat upper tract infection 2

Adjusting Therapy

• Adjust antibiotics based on culture and sensitivity results when available (typically 48-72 hours) 1, 2
• Consider local antibiotic resistance patterns when selecting empiric therapy 1, 2, 3
• If fever persists beyond 48 hours of appropriate therapy, reevaluate for treatment failure, resistant organisms, or anatomic abnormalities 2

Imaging Recommendations

Renal and bladder ultrasonography (RBUS): 1, 2

• Perform for all febrile infants <2 years with first UTI to detect anatomic abnormalities
• Timing: Can be done during acute illness or shortly after

Voiding cystourethrography (VCUG): 1, 2

• NOT recommended routinely after first UTI
• Perform VCUG if:
  • RBUS shows hydronephrosis, scarring, or findings suggesting high-grade VUR or obstruction
  • Second febrile UTI occurs
  • Atypical or complex clinical circumstances

This represents a major shift from older guidelines that recommended routine VCUG after first UTI, as recent evidence shows antimicrobial prophylaxis does not prevent scarring in most cases of VUR grades I-IV 1, 5

Follow-Up Strategy

Immediate (1-2 days): 2

• Clinical reassessment to confirm fever resolution and response to antibiotics
• This is when treatment failures become apparent—do not delay this follow-up

Long-term: 1, 2

• No routine scheduled visits after successful treatment of uncomplicated first UTI
• Instruct parents to seek prompt evaluation (within 48 hours) for any future febrile illness, as recurrent UTI risk is significant
• After second febrile UTI, obtain VCUG to evaluate for VUR

Antibiotic Prophylaxis

Prophylaxis is NOT routinely recommended for: 1, 2, 5

• Children after first UTI
• Children with recurrent UTIs
• Children with VUR grades I-IV
• Children with isolated hydronephrosis
• Children with neurogenic bladder

Consider prophylaxis only for: 2, 5, 3

• Significant obstructive uropathies until surgical correction
• High-grade VUR (grades III-V) with recurrent febrile UTIs (though evidence is mixed)

The RIVUR trial showed prophylaxis reduced recurrent UTI by ~50% but did not reduce renal scarring, and the emergence of antimicrobial resistance is a proven risk 2, 5

Dosing for Common Antibiotics

Trimethoprim-sulfamethoxazole: 6, 7

• 40 mg/kg sulfamethoxazole + 8 mg/kg trimethoprim per 24 hours, divided every 12 hours for 10-14 days
• Not recommended for children <2 months

Amoxicillin-clavulanate: 2

• 20-40 mg/kg/day (amoxicillin component) divided every 8-12 hours

Critical Pitfalls to Avoid

• Delaying treatment—early antimicrobial therapy (ideally within 48 hours of fever onset) may decrease risk of renal scarring 2, 8
• Using nitrofurantoin for febrile UTI—this is for uncomplicated cystitis only 2
• Treating for <7 days for febrile UTI—this increases treatment failure rates 2
• Failing to obtain culture before antibiotics—this prevents appropriate de-escalation 2, 4
• Treating asymptomatic bacteriuria—this does not require treatment and promotes resistance 8, 4
• Routine VCUG after first UTI—this is outdated practice 1, 2

When to Refer to Specialist

Refer for: 2

• Abnormal RBUS showing hydronephrosis, scarring, or structural abnormalities
• Recurrent febrile UTIs (≥2 episodes)
• Poor response to appropriate antibiotics within 48 hours
• Non-E. coli organisms suggesting complicated infection
• Age <3 months with febrile UTI (consider urology/nephrology consultation)