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Emergency and Acute Medicine: Urinary Tract Infections (Pediatric)
Pediatric urinary tract infections (UTIs) occur when bacteria colonize the urinary tract, most commonly via retrograde spread from rectal or perineal flora. In infants, hematogenous spread can also occur, while in older children, Vesicoureteral reflux is a major predisposing factor. A definitive diagnosis requires a urine culture showing a single organism at >10,000 CFU/mL obtained from a catheterized or suprapubic specimen, as contamination rates are high with other collection methods. UTIs are particularly important in young infants because those aged 0–3 months have up to a 30% risk of associated sepsis.
Several risk factors increase susceptibility, including female sex (due to a shorter urethra), poor perineal hygiene, infrequent voiding, constipation, and sexual activity in adolescents. Lack of male circumcision may also increase risk. UTIs occur in approximately 4–7% of febrile infants. The most common pathogen is Escherichia coli, responsible for about 80% of cases, followed by organisms such as Klebsiella pneumoniae, Staphylococcus aureus, Enterobacter, Proteus, Pseudomonas aeruginosa, and Enterococcus species.
Clinical presentation varies significantly by age and is often nonspecific, especially in younger children. Neonates may present with signs of sepsis such as poor feeding, irritability, lethargy, fever, or even hypothermia. Children aged 1 month to 3 years commonly present with fever, vomiting, diarrhea, abdominal pain, and failure to thrive. In children older than 3 years, symptoms become more typical and include dysuria, urinary frequency, enuresis, abdominal or flank pain, fever, hematuria, and foul-smelling urine. Severe infections may present with systemic toxicity, including high fever, chills, and costovertebral angle tenderness.
Diagnosis can be challenging and requires laboratory confirmation. Urinalysis with microscopy and Gram stain is essential, although it has limited sensitivity in infants, and up to 80% of neonates with confirmed UTI may have a normal urinalysis. Leukocyte esterase suggests pyuria, while nitrites indicate nitrate-reducing bacteria, though false negatives are common. Urine culture remains the gold standard and must be processed promptly. Catheterization is the preferred method for obtaining urine in infants and young children due to high contamination rates with bag or clean-catch specimens. Blood tests, including CBC and blood cultures, are recommended in young or febrile children to evaluate for bacteremia.
Imaging plays an important role in selected cases. Renal and bladder ultrasound is used to detect structural abnormalities and is recommended in children under 2 years with a first febrile UTI, those with recurrent infections, or poor response to treatment. Voiding cystourethrogram (VCUG) may be used to detect vesicoureteral reflux, although its routine use is debated. Additional imaging may be indicated based on clinical severity and recurrence.
The differential diagnosis includes vulvovaginitis, viral cystitis, urethritis (including sexually transmitted infections in adolescents), glomerulonephritis, appendicitis, trauma, nephrolithiasis, diabetes, and possible abuse in certain contexts. Careful evaluation is essential to avoid misdiagnosis.
Management depends on age and severity. Infants younger than 3 months with suspected UTI should be treated empirically for sepsis with intravenous antibiotics such as ampicillin and gentamicin. Older children who are stable may be treated with oral antibiotics for 10–14 days, guided by local resistance patterns. Common options include amoxicillin, amoxicillin-clavulanate, cephalexin, trimethoprim–sulfamethoxazole, and third-generation cephalosporins such as cefixime or cefdinir. Shorter courses (≈5 days) may be considered in older children with uncomplicated, afebrile infections.
Hospital admission is indicated for infants under 3 months, toxic appearance, dehydration, inability to tolerate oral medications, suspected pyelonephritis, urinary obstruction, immunocompromised state, or failure of outpatient therapy. Patients who are stable, hydrated, and able to take oral medications with reliable follow-up may be discharged.
Follow-up is essential to ensure resolution of infection, monitor for recurrence, and evaluate for underlying abnormalities such as reflux or structural anomalies. Long-term complications include recurrent UTIs, renal scarring, hypertension, and chronic kidney disease. Early diagnosis and treatment are critical to reducing these risks.
Key clinical points include recognizing that symptoms are often nonspecific in young children, that laboratory confirmation is essential, and that febrile infants with UTIs are at risk for bacteremia and require careful evaluation and management.
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