What are the key points to cover when discussing pediatric urinary tract infections (UTIs) in terms of clinical presentation, diagnosis, treatment, and prevention?

Pediatric Urinary Tract Infections: Clinical and Shelf-Relevant Presentation

The most effective approach to pediatric UTIs requires proper specimen collection, prompt diagnosis, appropriate antimicrobial therapy based on local resistance patterns, and selective imaging to identify underlying abnormalities that could lead to renal scarring and long-term complications. 1

Epidemiology and Risk Factors

• UTIs are the second most common bacterial infection in children and the most frequent site of occult bacterial infections in febrile infants 1, 2
• Prevalence is approximately 5% in febrile infants 2-24 months of age 1
• Risk factors vary by age and gender:
  • Uncircumcised male infants have higher risk than circumcised males 1
  • Female infants and children have higher risk after 12 months of age 1
  • Congenital anomalies of the kidney and urinary tract (CAKUT) are found in approximately 30% of children with UTIs 3
  • Functional abnormalities like bladder and bowel dysfunction contribute to recurrent UTIs 2

Clinical Presentation

• Presentation varies significantly by age, with younger children having more nonspecific symptoms 4
• In infants and young children (2-24 months):
  • Fever without obvious source is often the only symptom 1
  • Other nonspecific symptoms include irritability, poor feeding, vomiting, and failure to thrive 4
• In verbal children:
  • Dysuria, frequency, urgency, abdominal/flank pain, and enuresis may be reported 4
• Distinguishing cystitis from pyelonephritis in young children is challenging:
  • Fever >38°C, poor feeding, and systemic symptoms suggest pyelonephritis 1
  • Absence of fever with primarily urinary symptoms suggests cystitis 1

Diagnosis

• Proper urine specimen collection is critical to avoid contamination and misdiagnosis 1:

  • Suprapubic aspiration or urethral catheterization are preferred methods for non-toilet-trained children 1, 3
  • Clean-catch midstream urine is acceptable for toilet-trained children 3
  • Bag urine specimens have high contamination rates and should only be used to rule out UTI when negative 1, 3

• Urinalysis interpretation:

  • Positive leukocyte esterase and/or nitrite on dipstick suggests UTI 1
  • Microscopy showing pyuria (>5 WBC/HPF) and bacteriuria supports diagnosis 1
  • Urinalysis alone cannot definitively diagnose UTI; culture is required 1

• Urine culture criteria for UTI diagnosis:

  • ≥50,000 CFU/mL of a single uropathogen from catheterized or suprapubic specimen 1
  • Common pathogens include E. coli (80-90%), Klebsiella, Proteus, and Enterococcus 4
  • Organisms like Lactobacillus, coagulase-negative staphylococci, and Corynebacterium are typically contaminants 1

Treatment

• Empiric therapy should be initiated promptly after urine collection to prevent renal scarring 1, 5

• Route of administration:

  • Oral therapy is appropriate for most children who can tolerate oral medications 1
  • Parenteral therapy is indicated for toxic-appearing children, those unable to tolerate oral intake, or when compliance is a concern 1

• Empiric antibiotic selection should be based on local resistance patterns 1:

  • Oral options include:
    • Amoxicillin-clavulanate: 20-40 mg/kg/day divided in 3 doses 1
    • Trimethoprim-sulfamethoxazole: 6-12 mg/kg trimethoprim and 30-60 mg/kg sulfamethoxazole per day in 2 doses (for children >2 months) 1, 6
    • Cephalosporins: Cefixime 8 mg/kg/day in 1 dose, cephalexin 50-100 mg/kg/day in 4 doses 1, 7
  • Parenteral options include:
    • Ceftriaxone: 75 mg/kg every 24 hours 1
    • Gentamicin: 7.5 mg/kg/day divided every 8 hours 1

• Duration of therapy:

  • 7-14 days is recommended for febrile UTIs/pyelonephritis 1
  • 3-5 days may be sufficient for afebrile cystitis in older children 1
  • Adjust antibiotics based on culture and sensitivity results when available 1

Imaging and Follow-up

• Renal and bladder ultrasonography (RBUS) is recommended after first febrile UTI to detect anatomic abnormalities 1

• Voiding cystourethrography (VCUG) is not routinely recommended after first UTI but should be performed if 1:

  • Ultrasound reveals hydronephrosis, scarring, or findings suggesting high-grade VUR or obstructive uropathy
  • There is recurrence of febrile UTI
  • Other atypical or complex clinical circumstances exist

• Follow-up considerations:

  • Clinical improvement (including fever resolution) typically occurs within 48-72 hours of treatment 1
  • Additional workup or treatment reassessment is warranted if no improvement within this timeframe 1
  • Parents should be instructed to seek prompt medical evaluation (within 48 hours) for future febrile illnesses to detect and treat recurrent UTIs early 1

Prevention of Recurrent UTIs

• Routine antibiotic prophylaxis is not recommended for all children after first UTI 1
• Management of underlying risk factors is essential:
  • Evaluation and treatment of bladder and bowel dysfunction in toilet-trained children 2
  • Proper hygiene practices and adequate hydration 2
  • Prompt treatment of constipation 2

Long-term Complications

• Renal scarring is the most significant complication of UTIs, particularly with delayed treatment 5, 2
• Risk factors for renal scarring include:
  • Young age at first UTI (especially <1 year) 5
  • Recurrent UTIs 1
  • Delayed treatment 1, 5
  • High-grade vesicoureteral reflux 1
• Long-term sequelae of renal scarring may include hypertension and reduced renal function, though population-based studies suggest these are rare complications 5, 4

Common Pitfalls to Avoid

• Using bag urine specimens for UTI diagnosis leads to overdiagnosis and overtreatment 1
• Treating asymptomatic bacteriuria may be harmful and promotes antimicrobial resistance 1
• Delaying treatment in febrile infants with suspected UTI increases risk of renal scarring 1, 5
• Failure to adjust antibiotics based on culture results and local resistance patterns 1
• Missing underlying anatomic or functional abnormalities that predispose to recurrent UTIs 2