Prevalence of Invasive Bacterial Infection in Hypothermic Young Infants: A Multisite Study.

OBJECTIVE: To determine the prevalence of bacteremia and meningitis (invasive bacterial infection [IBI]) in hypothermic young infants, and also to determine the prevalence of serious bacterial infections (SBI) and neonatal herpes simplex virus and to identify characteristics associated with IBI. STUDY DESIGN: We conducted a retrospective cohort study of infants ≤90 days of age who presented to 1 of 9 hospitals with historical or documented hypothermia (temperature ≤36.0°C) from September 1, 2017, to May 5, 2021. Infants were identified by billing codes or electronic medical record search of hypothermic temperatures. All charts were manually reviewed. Infants with hypothermia during birth hospitalization, and febrile infants were excluded. IBI was defined as positive blood culture and/or cerebrospinal fluid culture treated as a pathogenic organism, whereas SBI also included urinary tract infection. We used multivariable mixed-effects logistic regression to identify associations between exposure variables and IBI. RESULTS: Overall, 1098 young infants met the inclusion criteria. IBI prevalence was 2.1% (95% CI, 1.3-2.9) (bacteremia 1.8%; bacterial meningitis 0.5%). SBI prevalence was 4.4% (95% CI, 3.2-5.6), and neonatal herpes simplex virus prevalence was 1.3% (95% CI, 0.6-1.9). Significant associations were found between IBI and repeated temperature instability (OR, 4.9; 95% CI, 1.3-18.1), white blood cell count abnormalities (OR, 4.8; 95% CI, 1.8-13.1), and thrombocytopenia (OR, 5.0; 95% CI, 1.4-17.0). CONCLUSIONS: IBI prevalence in hypothermic young infants is 2.1%. Further understanding of characteristics associated with IBI can guide the development decision tools for management of hypothermic young infants.

Time to Positive Blood and Cerebrospinal Fluid Cultures in Hypothermic Young Infants.

BACKGROUND AND OBJECTIVE: Hypothermia in young infants may be secondary to an invasive bacterial infection. No studies have explored culture time-to-positivity (TTP) in hypothermic infants. Our objective was to compare TTP of blood and cerebrospinal fluid (CSF) cultures between pathogenic and contaminant bacteria in hypothermic infants ≤90 days of age. METHODS: Secondary analysis of a retrospective cohort of 9 children's hospitals. Infants ≤90 days of age presenting to the emergency department or inpatient setting with hypothermia from September 1, 2017, to May 5, 2021, with positive blood or CSF cultures were included. Differences in continuous variables between pathogenic and contaminant organism groups were tested using a 2-sample t test and 95% confidence intervals for the mean differences reported. RESULTS: Seventy-seven infants met inclusion criteria. Seventy-one blood cultures were positive, with 20 (28.2%) treated as pathogenic organisms. Five (50%) of 10 positive CSF cultures were treated as pathogenic. The median (interquartile range [IQR]) TTP for pathogenic blood cultures was 16.8 (IQR 12.7-19.2) hours compared with 26.11 (IQR 20.5-48.1) hours for contaminant organisms (P < .001). The median TTP for pathogenic organisms on CSF cultures was 34.3 (IQR 2.0-53.7) hours, compared with 58.1 (IQR 52-72) hours for contaminant CSF organisms (P < .186). CONCLUSIONS: Our study is the first to compare the TTP of blood and CSF cultures between pathogenic and contaminant bacteria in hypothermic infants. All pathogenic bacteria in the blood grew within 36 hours. No difference in TTP of CSF cultures between pathogenic and contaminant bacteria was detected.

Performance of Febrile Infant Decision Tools on Hypothermic Infants Evaluated for Infection.

BACKGROUND: Given the lack of evidence-based guidelines for hypothermic infants, providers may be inclined to use febrile infant decision-making tools to guide management decisions. Our objective was to assess the diagnostic performance of febrile infant decision tools for identifying hypothermic infants at low risk of bacterial infection. METHODS: We conducted a secondary analysis of a retrospective cohort study of hypothermic (≤36.0 C) infants ≤90 days of age presenting to the emergency department or inpatient unit among 9 participating sites between September 1, 2016 and May 5, 2021. Well-appearing infants evaluated for bacterial infections via laboratory testing were included. Infants with complex chronic conditions or premature birth were excluded. Performance characteristics for detecting serious bacterial infection (SBI; urinary tract infection, bacteremia, bacterial meningitis) and invasive bacterial infection (IBI; bacteremia, bacterial meningitis) were calculated for each tool. RESULTS: Overall, 314 infants met the general inclusion criteria, including 14 cases of SBI (4.5%) and 7 cases of IBI (2.2%). The median age was 5 days, and 68.1% of the infants (214/314) underwent a full sepsis evaluation. The Philadelphia, Boston, IBI Score, and American Academy of Pediatrics Clinical Practice Guideline did not misclassify any SBI or IBI as low risk; however, they had low specificity and positive predictive value. Rochester and Pediatric Emergency Care Applied Research Network tools misclassified infants with bacterial infections. CONCLUSIONS: Several febrile infant decision tools were highly sensitive, minimizing missed SBIs and IBIs in hypothermic infants. However, the low specificity of these decision tools may lead to unnecessary testing, antimicrobial exposure, and hospitalization.

Variation in Care of Well-Appearing Hypothermic Young Infants: A Multisite Study.

BACKGROUND AND OBJECTIVES: Numerous decision tools have emerged to guide management of febrile infants, but limited data exist to guide the care of young infants presenting with hypothermia. We evaluated the variation in care for well-appearing hypothermic young infants in the hospital and/or emergency department setting between participating sites. METHODS: This is a retrospective cohort study of well-appearing infants ≤90 days old across 9 academic medical centers from September 1, 2016 to May 5, 2021. Infants were identified via billing codes for hypothermia or an initial temperature ≤36.0°C with manual chart review performed. Primary outcomes included assessment of variation in diagnostic evaluation, disposition, empirical antimicrobial therapy, and length of stay. RESULTS: Of 14 278 infants originally identified, 739 met inclusion criteria. Significant interhospital variation occurred across all primary outcomes. Across sites, a full serious bacterial illness evaluation was done in 12% to 76% of hypothermic infants. Empirical antibiotics were administered 20% to 87% of the time. Performance of herpes simplex viral testing ranged from 7% to 84%, and acyclovir was empirically started 8% to 82% of the time. Hospital admission rates ranged from 45% to 100% of patients. CONCLUSIONS: Considerable variation across multiple aspects of care exists for well-appearing young infants presenting with hypothermia. An improved understanding of hypothermic young infants and their risk of infection can lead to the development of clinical decision tools to guide appropriate evaluation and management.