Texas — Targeted Issue

Author(s)/Presenter(s)

Andrea Cruz, Prashant Mahajan, Bema Bonsu, Jonathan Bennett, Deborah Levine, Elizabeth Alpern, Lise Nigrovic, Shireen Atabaki, Daniel Cohen, John VanBuren, Octavio Ramilo, Nathan Kuppermann, Febrile Infant Working Group of PECARN

Abstract/Description

Importance: Clinicians often risk stratify young febrile infants for invasive bacterial infections (IBIs), defined as bacteremia and/or bacterial meningitis, using complete blood cell count parameters.

Objective: To estimate the accuracy of individual complete blood cell count parameters to identify febrile infants with IBIs.

Design, setting, and participants: Planned secondary analysis of a prospective observational cohort study comprising 26 emergency departments in the Pediatric Emergency Care Applied Research Network from 2008 to 2013. We included febrile (≥38°C), previously healthy, full-term infants younger than 60 days for whom blood cultures were obtained. All infants had either cerebrospinal fluid cultures or 7-day follow-up.

Main outcomes and measures: We tested the accuracy of the white blood cell count, absolute neutrophil count, and platelet count at commonly used thresholds for IBIs. We determined optimal thresholds using receiver operating characteristic curves.

Results: Of 4313 enrolled infants, 1340 (31%; 95% CI, 30% to 32%) were aged 0 to 28 days, 2412 were boys (56%), and 2471 were white (57%). Ninety-seven (2.2%; 95% CI, 1.8% to 2.7%) had IBIs. Sensitivities were low for common complete blood cell count parameter thresholds: white blood cell count less than 5000/µL, 10% (95% CI, 4% to 16%) (to convert to 109 per liter, multiply by 0.001); white blood cell count ≥15 000/µL, 27% (95% CI, 18% to 36%); absolute neutrophil count ≥10 000/µL, 18% (95% CI, 10% to 25%) (to convert to × 109 per liter, multiply by 0.001); and platelets <100 × 103/µL, 7% (95% CI, 2% to 12%) (to convert to × 109 per liter, multiply by 1). Optimal thresholds for white blood cell count (11 600/µL), absolute neutrophil count (4100/µL), and platelet count (362 × 103/µL) were identified in models that had areas under the receiver operating characteristic curves of 0.57 (95% CI, 0.50-0.63), 0.70 (95% CI, 0.64-0.76), and 0.61 (95% CI, 0.55-0.67), respectively.

Conclusions and relevance: No complete blood cell count parameter at commonly used or optimal thresholds identified febrile infants 60 days or younger with IBIs with high accuracy. Better diagnostic tools are needed to risk stratify young febrile infants for IBIs.

Author(s)/Presenter(s)

Leah Tzimenatos, Prashant Mahajan, Peter S. Dayan, Melissa Vitale, James G. Linakis, Stephen Blumberg, Dominic Borgialli, Richard M. Ruddy, John Van Buren, Octavio Ramilo, Nathan Kuppermann, PECARN

Abstract/Description

Objectives: Reports of the test accuracy of the urinalysis for diagnosing urinary tract infections (UTIs) in young febrile infants have been variable. We evaluated the test characteristics of the urinalysis for diagnosing UTIs, with and without associated bacteremia, in young febrile infants.

Methods: We performed a planned secondary analysis of data from a prospective study of febrile infants ≤60 days old at 26 emergency departments in the Pediatric Emergency Care Applied Research Network. We evaluated the test characteristics of the urinalysis for diagnosing UTIs, with and without associated bacteremia, by using 2 definitions of UTI: growth of ≥50 000 or ≥10 000 colony-forming units (CFUs) per mL of a uropathogen. We defined a positive urinalysis by the presence of any leukocyte esterase, nitrite, or pyuria (>5 white blood cells per high-power field).

Results: Of 4147 infants analyzed, 289 (7.0%) had UTIs with colony counts ≥50 000 CFUs/mL, including 27 (9.3%) with bacteremia. For these UTIs, a positive urinalysis exhibited sensitivities of 0.94 (95% confidence interval [CI]: 0.91-0.97), regardless of bacteremia; 1.00 (95% CI: 0.87-1.00) with bacteremia; and 0.94 (95% CI: 0.90-0.96) without bacteremia. Specificity was 0.91 (95% CI: 0.90-0.91) in all groups. For UTIs with colony counts ≥10 000 CFUs/mL, the sensitivity of the urinalysis was 0.87 (95% CI: 0.83-0.90), and specificity was 0.91 (95% CI: 0.90-0.92).

Conclusions: The urinalysis is highly sensitive and specific for diagnosing UTIs, especially with ≥50 000 CFUs/mL, in febrile infants ≤60 days old, and particularly for UTIs with associated bacteremia.

Author(s)/Presenter(s)

Elizabeth Powel, Prashant Mahajan, Genie Roosevelt, John Hoyle Jr, Rajender Gattu, Andrea Cruz, Alexander Rogers, Shireen Atabaki, David Jaffe, T Charles Casper, Octavio Ramilo, Nathan Kuppermann, Febrile Infant Working Group of PECARN

Abstract/Description

Study objective: To describe the current epidemiology of bacteremia in febrile infants 60 days of age and younger in the Pediatric Emergency Care Applied Research Network (PECARN).

Methods: We conducted a planned secondary analysis of a prospective observational study of febrile infants 60 days of age and younger presenting to any of 26 PECARN emergency departments (2008 to 2013) who had blood cultures obtained. We excluded infants with significant comorbidities or critically ill appearance. The primary outcome was prevalence of bacteremia.

Results: Of 7,335 screened infants, 4,778 (65.1%) had blood cultures and were enrolled. Of these patients, 84 had bacteremia (1.8%; 95% confidence interval [CI] 1.4% to 2.2%). The prevalence of bacteremia in infants aged 28 days or younger (47/1,515) was 3.1% (95% CI 2.3% to 4.1%); in infants aged 29 to 60 days (37/3,246), 1.1% (95% CI 0.8% to 1.6%). Prevalence differed by week of age for infants 28 days of age and younger (0 to 7 days: 4/156, 2.6%; 8 to 14 days: 19/356, 5.3%; 15 to 21 days: 15/449, 3.3%; and 22 to 28 days: 9/554, 1.6%). The most common pathogens were Escherichia coli (39.3%; 95% CI 29.5% to 50.0%) and group B streptococcus (23.8%; 95% CI 16.0% to 33.9%). Bacterial meningitis occurred in 19 of 1,515 infants 28 days of age and younger (1.3%; 95% CI 0.8% to 2.0%) and 5 of 3,246 infants aged 29 to 60 days (0.2%; 95% CI 0.1% to 0.4%). Of 84 infants with bacteremia, 36 (42.9%; 95% CI 32.8% to 53.5%) had urinary tract infections (E coli 83%); 11 (13.1%; 95% CI 7.5% to 21.9%) had bacterial meningitis.

Conclusion: The prevalence of bacteremia and meningitis among febrile infants 28 days of age and younger is high and exceeds that observed in infants aged 29 to 60 days. E coli and group B streptococcus are the most common bacterial pathogens.

Author(s)/Presenter(s)

Lise Nigrovic, Prashant Mahajan, Stephen Blumberg, Lorin Browne, James Linakis, Richard Ruddy, Jonathan Bennett, Alexander Rogers, Leah Tzimenatos, Elizabeth Powell, Elizabeth Alpern, T. Charles Casper, Octavio Ramilo, Nathan Kuppermann

Abstract/Description

Objectives: To assess the performance of the Yale Observation Scale (YOS) score and unstructured clinician suspicion to identify febrile infants ≤60 days of age with and without serious bacterial infections (SBIs).

Methods: We performed a planned secondary analysis of a prospective cohort of non-critically ill, febrile, full-term infants ≤60 days of age presenting to 1 of 26 participating emergency departments in the Pediatric Emergency Care Applied Research Network. We defined SBIs as urinary tract infections, bacteremia, or bacterial meningitis, with the latter 2 considered invasive bacterial infections. Emergency department clinicians applied the YOS (range: 6-30; normal score: ≤10) and estimated the risk of SBI using unstructured clinician suspicion (<1%, 1%-5%, 6%-10%, 11%-50%, or >50%).

Results: Of the 4591 eligible infants, 444 (9.7%) had SBIs and 97 (2.1%) had invasive bacterial infections. Of the 4058 infants with YOS scores of ≤10, 388 (9.6%) had SBIs (sensitivity: 51/439 [11.6%]; 95% confidence interval [CI]: 8.8%-15.0%; negative predictive value: 3670/4058 [90.4%]; 95% CI: 89.5%-91.3%) and 72 (1.8%) had invasive bacterial infections (sensitivity 23/95 [24.2%], 95% CI: 16.0%-34.1%; negative predictive value: 3983/4055 [98.2%], 95% CI: 97.8%-98.6%). Of the infants with clinician suspicion of <1%, 106 had SBIs (6.4%) and 16 (1.0%) had invasive bacterial infections.

Conclusions: In this large prospective cohort of febrile infants ≤60 days of age, neither the YOS score nor unstructured clinician suspicion reliably identified those with invasive bacterial infections. More accurate clinical and laboratory predictors are needed to risk stratify febrile infants.