Risk of Bacterial Coinfections in Febrile Infants 60 Days Old and Younger with Documented Viral Infections.

Objective To determine the risk of serious bacterial infections (SBIs) in young febrile infants with and without viral infections. Study design Planned secondary analyses of a prospective observational study of febrile infants 60 days of age or younger evaluated at 1 of 26 emergency departments who did not have clinical sepsis or an identifiable site of bacterial infection. We compared patient demographics. clinical, and laboratory findings, and prevalence of SBIs between virus-positive and virus-negative infants. Results Of the 4778 enrolled infants, 2945 (61.6%) had viral testing performed, of whom 1200 (48.1%) were virus positive; 44 of the 1200 had SBIs (3.7%; 95% CI, 2.7%-4.9%). Of the 1745 virus-negative infants, 222 had SBIs (12.7%; 95% CI, 11.2%-14.4%). Rates of specific SBIs in the virus-positive group vs the virus-negative group were: UTIs (33 of 1200 [2.8%: 95% CI, 1.9%-3.8%] vs 186 of 1745 [10.7%: 95% CI, 9.2%12.2%]) and bacteremia (9 of 1199 [0.8%; 95% CI, 0.3%-1.4%] vs 50 of 1743 [2.9%; 95% CI, 2.1%-3.8%]). The rate of bacterial meningitis tended to be lower in the virus-positive group (0.4%) than in the viral-negative group (0.8%); the difference was not statistically significant. Negative viral status (aOR. 3.2; 95% CI, 2.3-4.6), was significantly associated with SBI in multivariable analysis. Conclusions Febrile infants 60 days of age with viral infections are at significantly lower, but non-negligible risk for SBIs, including bacteremia and bacterial meningitis.