Infants ≤60 days old with fever and confirmed viral infection are at a substantially lower risk for serious bacterial infection compared to infants without a virus, according to new findings published in the Journal of Pediatrics.

Previous research has attempted to determine the risk for serious bacterial infection in febrile infants with viral infection, but limitations of these studies include small cohorts, a retrospective study design, evaluation of a single viral infection, and lack of up-to-date research. In this study, the researchers conducted a subanalysis of a large, multicenter, prospective cohort study that included 4778 infants age 60 days or younger to evaluate the prevalence of serious bacterial infections between infants with a confirmed viral infection vs those without a viral infection.

In a cohort of 2945 infants, 61.6% underwent viral testing, with 48.1% (n=1200) of participants demonstrating a positive test result. Of this subgroup, 44 of the 1200 had serious bacterial infections (3.7%; 95% CI, 2.7%-4.9%), and among remaining infants, 222 had serious bacterial infections (12.7%; 95% CI, 11.2%-14.4%). The rate of urinary tract infections in the infants who tested positive for a viral infection was 33 of 1200 (2.8%) vs 186 of 1745 (10.7%) infants who did not have a viral infection. Bacteremia developed in 9 of 1199 (0.8%) infants who had a viral infection vs 50 of 1743 (2.9%) infants who did not. In addition, the rate of bacterial meningitis was also lower in infants who tested positive for virus (0.4%) vs those who did not (0.8%), although the difference was not statistically significant. In multivariable analysis, negative viral status (adjusted odds ratio 3.2; 95% CI, 2.3-4.6) was significantly associated with serious bacterial infection in young febrile infants.

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“However, the non-negligible 3.7% rate of serious bacterial infections occurrence, including the 1.0% rate of invasive bacterial infections (bacteremia and meningitis), in febrile infants who tested positive for a viral infection should be taken into consideration during clinical decision making regarding evaluation, management, and disposition,” wrote the study authors.


Mahajan P, Browne LR, Levine DA, et al. Risk of bacterial coinfections in febrile infants 60 days old and younger with documented Viral Infections [published online September 6, 2018]. J Pediatr. doi: 10.1016/j.jpeds.2018.07.073

This article originally appeared on Infectious Disease Advisor