The 2011 American Academy of Pediatrics urinary tract infection (UTI) guideline suggests incorporation of a positive urinalysis (UA) into the definition of UTI. However, concerns linger over UA sensitivity in young infants. Infants with the same pathogenic organism in the blood and urine (bacteremic UTI) have true infections and represent a desirable population for examination of UA sensitivity.

Parenteral antibiotic treatment duration in young infants with bacteraemic UTI was variable and only minimally explained by measurable patient factors. Relapses were rare and were not associated with treatment duration. Shorter parenteral courses may be appropriate in some infants.

Objectives: To report the prevalence of bacteremia by age in a sample of infants <1 year of age with urinary tract infections (UTIs), to compare characteristics of infants with UTIs with and without bacteremia, and to describe treatment courses and 30-day outcomes in infants with UTIs with and without bacteremia. Methods: We used a retrospective cross-sectional design to determine the prevalence of bacteremia in infants with UTIs at our institution. A double cohort design matching for age and gender was used to compare clinical characteristics and outcomes between infants with bacteremic versus nonbacteremic UTIs. Results: We identified 1379 UTIs, with blood cultures obtained in 52% of cases. The prevalence of bacteremia was 4.1% (95% confidence interval 3.1%–5.3%) for all UTIs and 8% (95% confidence interval 6.1%–10.2%) for UTIs in which blood culture was obtained. Fifty-five infants with bacteremic UTIs were compared with 110 infants with nonbacteremic UTIs. Except for minor differences in the urinalysis and serum band count, there were no significant differences in clinical presentation between the 2 groups. Bacteremic infants received longer parenteral treatment courses than nonbacteremic infants (mean 6.7 vs 2.4 days, P < .001). Treatment courses in the bacteremic group were variable and predicted by age but not severity of illness. No bacteremic infant had recurrent UTI or bacteremia with the same organism within 30 days of discharge. Conclusions: Treatment was variable but outcomes were excellent in infants with bacteremic UTIs.

The risk of rebound hyperbilirubinemia can be quantified according to an infant's gestational age, age at phototherapy initiation, and TSB relative to the treatment threshold at phototherapy termination.

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Although RUS and VCUG abnormalities were common in this cohort, the frequency and severity were similar to previous studies of infants with UTIs in general. Our findings do not support special consideration of bacteremia in imaging decisions for otherwise well-appearing young infants with UTI.

OBJECTIVES: We previously reported a clinical prediction rule to estimate the probability of rebound hyperbilirubinemia using gestational age (GA), age at phototherapy initiation, and total serum bilirubin (TSB) relative to the treatment threshold at phototherapy termination. We investigated (1) how a simpler 2-variable model would perform and (2) the absolute rebound risk if phototherapy were stopped at 2 mg/dL below the threshold for treatment initiation. METHODS: Subjects for this retrospective cohort study were infants born 2012–2014 at ≥35 weeks’ gestation at 1 of 17 Kaiser Permanente hospitals who underwent inpatient phototherapy before age 14 days. TSB reaching the phototherapy threshold within 72 hours of phototherapy termination was considered rebound. We simplified by using the difference between the TSB level at the time of phototherapy termination and the treatment threshold at the time of phototherapy initiation as 1 predictor, and kept GA as the other predictor. RESULTS: Of the 7048 infants treated with phototherapy, 4.6% had rebound hyperbilirubinemia. The area under the receiver operating characteristic curve was 0.876 (95% confidence interval, 0.854 to 0.899) for the 2-variable model versus 0.881 (95% confidence interval, 0.859 to 0.903) for the 3-variable model. The rebound probability after stopping phototherapy at 2 mg/dL below the starting threshold was 2.5% for infants ≥38 weeks’ GA and 10.2% for infants <38 weeks’ GA. CONCLUSIONS: Rebound hyperbilirubinemia can be predicted by a simpler 2-variable model consisting of GA and the starting threshold–ending TSB difference. Infants <38 weeks’ gestation may need longer phototherapy because of their higher rebound risk.

U rinary tract infections (UTIs) are the most common bacterial infection and one of the most common reasons for hospitalization in young infants. 1,2 The American Academy of Pediatrics (AAP) has published several clinical practice guidelines for the evaluation and management of febrile children ages 2-24 months with first-time UTIs, most recently in 2011 and affirmed in 2016. 3 These guidelines do not provide recommendations for infants aged <2 months, which leads to uncertainty regarding the diagnosis and management of UTIs for infants in this age group. We assess the applicability of the AAP UTI Guideline's action statements for infants aged <2 months presenting with first-time UTIs, with an emphasis on recent evidence. Because the considerations for bacterial infections differ for febrile infants aged <2 months compared with older infants, we do not discuss action statements one and two (determination of the likelihood of UTIs and decision to test urine) and statement seven (medical evaluation for fever after first UTI). 3 Additionally, because concomitant bacteremia and meningitis are more common in this age group than in older infants, we review some of the controversies surrounding the diagnosis and treatment of these disease entities. DIAGNOSIS"Action Statement 3: To establish the diagnosis of UTI, clinicians should require both urinalysis results that suggest infection (pyuria and/or bacteriuria) and the presence of at least 50,000 colony-forming units (CFUs) per mL of a uropathogen cultured from a urine specimen obtained through catheterization or SPA." 3 To distinguish asymptomatic bacteriuria or contamination from a true UTI, the AAP Guideline requires both a positive urinalysis (UA) and culture for a diagnosis of a UTI. 3 Historically, the UA was considered to be poorly sensitive for infections in young infants, with older studies reporting sensitivities ranging from 40% to 82% using urine culture as the gold standard. 4-7 Thus, infants aged <2 months with positive urine cultures and negative UAs are often treated as having true UTIs, though this practice varies by institution. 8 Possible explanations for the low UA sensitivity in this population include rapid bladder emptying, immature immune systems, and inability to concentrate urine. However, a negative UA plus a positive urine culture could also represent a "true negative" UA and a "false positive" culture, a finding that may be more common in young infants in whom sterile urine obtainment is often challenging.Two recent studies have addressed this issue by evaluating the UA sensitivity in patients with bacteremic UTIs, as growth of the same pathogenic organism from the blood and urine almost certainly represents true infection. 9,10 In a retrospective study of 203 infants aged <3 months with bacteremic UTIs, the presence of any leukocyte esterase (LE) or pyuria (>3 white blood cells per high-powered field [WBC/HPF]) had a sensitivity of 99.5% (95% CI: 98.5%-100%) and specificity of 93.9% (95% CI: 87.8%-93.2%). 9 In a prospective, multicenter stu...