Low prevalence of invasive bacterial infection in febrile infants under 3 months of age with enterovirus infection.

Infants under 3 months of age with fever without source (FWS) generally undergo a full, invasive septic evaluation to exclude invasive bacterial infection (IBI). Enterovirus (EV) infections are mostly banal and self-limiting and show a high prevalence rate at this age. We aimed to investigate the prevalence of IBI in EV-infected and uninfected infants under 3 months of age with FWS. This was a prospective observational cohort study of infants aged <90 days who were admitted because of FWS. As per protocol, blood and urine analysis and culture were obtained in all cases, and RNA EV from blood and/or cerebrospinal fluid samples was determined by real-time PCR. Three hundred and eighty-one previously healthy infants with FWS were included. EV infection was diagnosed in 64 children (16.8%; 95% confidence interval, 13.2-20.9%) and showed an uneventful evolution in all cases. Laboratory markers of infection were consistently lower in EV-infected patients; only one case of IBI (1.6%) was observed in an EV-infected patient as compared with 25.2% in EV-negative infants (p <0.001). Intravenous antibiotic use and length of stay were no different in EV-infected and uninfected patients. In our study, febrile infants (<90 days) diagnosed with EV infection showed a low risk of IBI when compared with uninfected patients. The systematic investigation of EV infection in young infants with FWS may allow a more conservative approach to the management of these patients. Further studies on this diagnostic approach are needed.