Prevalence of Bacterial Infection in Febrile Infant 61–90 Days Old Compared With Younger Infants

Abstract

The objective is to compare the prevalence of serious bacterial infection (SBI) and invasive bacterial infection (IBI) in febrile infants <60 days of age and in those between 61 and 90 days. Prospective registry-based cohort study including all the infants ≤90 days with fever without a source evaluated in a pediatric emergency department between 2003 and 2017. We compared the prevalence of SBI and IBI in febrile infants <60 days of age and those between 61 and 90 days. We included 3,301 infants. Overall, 605 (18.3%) had a SBI (mainly urinary tract infection), of these 81 (2.5%) had an IBI (bacteremia 60, meningitis 12, sepsis 9). The prevalence of SBI in infants >60 days old was 18.5% (95% CI: 16.4-20.7) versus 16.6% (95% CI: 14.7-18.7; n.s.) in those between 29 and 60 days and versus 21.5% (95% CI: 18.6-24.7; n.s.) in those <28 days of age. The prevalence of IBI among infants >60 days old was 1.1% (95% CI: 0.6-2.2) versus 2.3% (95% CI: 1.6-3.3; P < 0.05) in those between 29 and 60 days and 5.1% (95% CI: 3.7-7.0; P < 0.05) in those <28 days of age. The prevalence of IBI in well appearing >60 days was 1.0% (versus 4.5% in those <28 days old, P < 0.01; and 2.0% in those between 29 and 60 days, P = 0.06). All bacterial meningitis, except one, were diagnosed in infants <28 days. The prevalence of IBI in febrile infants between 61 and 90 days of age is high enough to support the recommendation for obtaining urine and blood tests in this population.