Written by Kimiko Dunbar
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Febrile infants 61 to 90 days who were positive for a respiratory virus had significantly lower rates of UTI (4.4% vs. 12.5%) and bacteremia (1 vs. 3%); no infants who were virus-positive had meningitis.
To tap or not to tap?
The AAP has clear clinical practice guidelines on the management of febrile infants 60 days and younger. However, data are lacking on what to do with the infants aged 61-90 days and no clinical practice guideline for this group. This retrospective cohort study analyzed 3,678 febrile infants aged 61-90 days, using the PECARN registry, to determine the prevalence of UTIs, bacteremia, and meningitis with/without respiratory viruses. Critically ill infants, premature infants <32 weeks gestation, and those with significant pre-existing medical conditions were excluded.
Viral-positive infants had significantly lower rates of UTI (4.4% vs 12.5%) and bacteremia (1.0% vs 3.0%); none had meningitis. There was variation in the rate of bacteremia without meningitis identified based on virus detected. Infants with SARS-CoV-2 had a lower prevalence of bacteremia; however, those with rhinovirus, RSV, and influenza had similar rates of bacteremia to those who tested negative. There were no cases of bacteremia in infants positive for human metapneumovirus, adenovirus and seasonal coronavirus. Limitations include lack of uniform viral testing (some only had rapid influenza/COVID-19/RSV, whereas others had more extensive testing), symptom data, and potential underestimation of bacterial infections.
How does this change my practice?
When I was in training, all febrile infants less than 90 days old got a septic work-up. Clinical practice guidelines from the AAP were updated in 2021 for infants ages 8-60 days. Suddenly, 70-day-old febrile baby was no different from a febrile 18 month old. This well-powered study is helpful. While assessment of risk in this age group requires nuance, I’ll be more comfortable monitoring a febrile infant with a virus-positive respiratory infection without further blood testing, although urine testing in this age-group is probably reasonable – a 4.4% rate of UTI is not insignificant. That said, I may also be more likely to order extended viral testing in this population to prove they are virus-positive and might consider the specific virus identified when deciding on the utility of blood cultures.
Source
Risk of Bacterial Infections in Febrile Infants 61 to 90 Days Old With Respiratory Viruses. Pediatrics. 2025 Jun 13:e2025070617. doi: 10.1542/peds.2025-070617. Epub ahead of print. PMID: 40506050
