The Risk for Serious Bacterial Infection among Infants with History of Prematurity: A Retrospective Cohort Study

Introduction: Neonatal fever in infants with a history of prematurity present a challenge to the treating physician. Literature on the topic is sparse and it is not clear how and until what age should their age be adjusted.

Methods: A single-center retrospective analysis for the years 2010-2020 (10 years). The charts of all emergency department (ED) visits by infants with a history of admission to the neonatal intensive care unit (NICU) were reviewed. The study inclusion criteria were: Prematurity (<37 weeks), Fever (at the ED or at home), and Age (<52 weeks from conception). For each visit information from the electronic records of the ED encounter and the NICU hospitalization were extracted. We then analyzed the rate of SBI by chronological and adjusted age.

Results: A total of 903 charts were reviewed and 297 (33%) met the inclusion criteria. The median age at the time of the visit was 10.7-weeks chronological or 3.6-weeks adjusted. Blood or CSF cultures were available in 97% of the cases (n=288), of which 3.8% were positive (n=11). Urine cultures were available in 90% of the cases (n=266), of which 11% were positive (n=28). Among the 171 infants who were otherwise low-risk infants, there were 5.8% cases with either UTI or bacteremia. The majority of which (70%) were infants under 3- months chronological age and 1- month adjusted age.

Conclusion: Well-appearing, otherwise low-risk infants, who were born prematurely, have a high risk for bacteremia or UTI until three-months chronological age and one-month adjusted age.