Table 2 outlines the initial choices of antibiotics until culture and sensitivities are known.
The choices and dosage of antibiotics are dependent on the age of the patient and are selected based on the other most likely organisms and their expected sensitivities (12). Ampicillin is added to the less than 2-month age group not only to cover Enterococcus, but also as part of broader neonatal sepsis coverage for Listeria. The third-generation cephalosporins are felt to be adequate initial coverage for most of the common organisms causing UTI. Children with congenital anomalies known to be associated with genitourinary abnormalities may be infected with less common organisms. In these situations, consider tailoring initial antibiotic coverage.
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Complications
The major complication of UTIs in infants is bacteremia. The rate of bacteremia in infants 0–3 months has variably been reported as 10% (13), 21–31% (14), and 36% (15). Infants with and without bacteremia are often clinically indistinguishable, making early determination of bacteremia difficult. A recent comprehensive review of 17 studies by Malik noted both C-reactive protein (CRP) and procalcitonin (PCT) results were highly variable in infants under 90 days old with known positive bacterial cultures (16). These inflammatory markers are therefore currently not useful to predict bacteremia. In addition to blood stream infection, other acute complications include meningitis, renal and perinephric abscess, and infected calculi. Longer-term complications include reflux nephropathy, renal scarring, hypertension, decreased renal function, and renal failure.
Duration of Antibiotic Therapy
While most uncomplicated UTIs are successfully treated with a 10-day treatment course, many experts prefer a 14-day course for neonates, infants, and ill-appearing young children. Despite effectiveness in adults, very-short-course therapy (≤3 days) for pediatric patients is associated with more treatment failures and reinfections (17). Although it may be considered in older children with cystitis, at this time it is not appropriate for treating infants and younger children in whom pyelonephritis cannot be distinguished from isolated lower tract infection (17,18).
Total treatment time and total days of parenteral therapy needed continue to be debated. Hoberman randomized children as young as 1 month of age to either entirely oral treatment or parenteral therapy for 3 days followed by oral treatment (19). In both arms of this study, children received 14 days of total therapy as was the standard at the time. He suggested, however, that a 10-day course of antibiotics should be adequate therapy for noncomplicated acute pyelonephritis. Of the 306 children, only 13 were under 2 months of age. Although only 13 positive blood cultures were reported, 10 of these occurred in children under 6 months of age. Given the limited number of children less than 2 months of age and the prevalence of positive blood cultures noted, conclusions cannot be drawn on the safety of entirely oral treatment for young infants. Parenteral antibiotic therapy should be continued for all hospitalized children until the patient is afebrile and free from signs of toxicity. Most hospitalized pediatric patients defervesce quickly on parenteral therapy—89% within 48 hours and 97% within 72 hours (20). Longer parenteral therapy of at least 10 days should be considered for neonates and infants with urosepsis, because they are immunologically immature, at greater risk of complications, have higher incidence of urinary tract anomalies, and have less reliable absorption of oral antibiotics.
Delayed or lack of response to antibiotic therapy may indicate the presence of urinary tract obstruction, resistant organisms, or renal or perinephric abscess. A repeat urine culture and immediate renal ultrasound or CT should be performed if the patient is not improving within 48 hours.