Serious Bacterial Infections in Hospitalized Febrile Infants in the First and Second Months of Life.

Abstract

Most protocols evaluating serious bacterial infection (SBI) risk in febrile infants classify neonates <30 days of age as high risk (HR), while other protocols do not distinguish between infants <30 and 30-60 days of age. We compared SBI rates in febrile infants at the first and the second months of life. This was a retrospective, population-based, cohort study. All febrile infants ≤60 days of age hospitalized in southern Israel, January 2013 through May 2014, were included. SBI risk assessment included medical history, physical examination, blood count and dipstick urine analysis. Overall, 623 infants were identified; 142 HR infants <30 days of age, 95 low-risk (LR) infants <30 days of age, 232 HR infants 30-60 days of age and 154 LR infants 30-60 days of age. Urinary tract infection comprised 84.7% (133/157) of all SBIs. Among HR infants, higher SBI rates were observed in <30 versus 30-60 days (45.0% vs. 29.3%; P = 0.003), while respective rates were similar among LR infants (8.4% vs. 11.0%; P = 0.66). SBI rates in HR infants 0-14 versus 15-60 days of age were 45.3% versus 33.6% (P = 0.12), and 19.2% versus 8.9% (P = 0.15) in LR infants. Among HR infants, SBI rates were 52.8% and 39.5% in infants <30 days of age with temperature ≥39°C and <39°C, respectively, while in infants ≥30 days of age, respective rates were 31.2% and 26.7% (P = 0.005, comparing the 4 groups). Among LR infants, rates were not affected by temperature degree. Thrombocytopenia was associated with higher SBI rates in HR, but not in LR. In HR infants, higher SBI rates were associated with younger age, higher body temperature and thrombocytopenia. In contrast, SBI (mostly urinary tract infection) rates among LR infants (approximately 10%) were not associated with these factors.