Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Introduction: Febrile infants ≤60 days of age are at increased risk for serious bacterial infections (SBIs), often necessitating extensive diagnostic evaluation and hospitalization. Although respiratory viral infections are common in this population and may influence the likelihood of concurrent bacterial infection, the relationship between respiratory viral panel (RVP) results and SBI risk remains an important consideration in clinical decision-making. The objective of this study was to evaluate the association between RVP results and the occurrence of SBIs among febrile infants ≤60 days of age.

Methods: In this single-center, retrospective study we analyzed data from infants ≤ 60 days of age who presented to the emergency department with fever (temperature > 100.4 o F/38 o C) between September 2020–May 2024. Infants were divided into two subgroups based on RVP results: positive or negative for any viral infections via a multiplex polymerase chain reaction panel. The overall rate of SBI,and the rates of individual SBIs (urinary tract infection [UTI], bacteremia, and bacterial meningitis), were compared between groups. The primary outcome was the rate of SBIs among infants with any positive RVP compared to those with a negative RVP.

Results: We analyzed 1,986 charts of febrile infants ≤ 60 days of age, of whom 485 (24.4%) met criteria. Of these, 309 (63.7%) had a positive RVP for at least one pathogen while 176 (36.3%) were all negative. Overall, the rate of serious bacterial infection in the RVP negative group was 35.8% (95% CI, 29%-43.1%) compared to 6.5% (95% CI, 4.1%-9.6%) in the RVP positive group (P < .001). Infants with a positive RVP had a significantly lower prevalence of serious bacterial infection (7.4%) and UTI (5.5%) compared to those with a negative RVP (P < .001). In the RVP positive group, 17 patients (5.5% [95% CI, 3.4%-8.5%]) had a UTI compared to 46 (26.1% [95% CI, 20.1%-33%]) in the RVP negative group. Notably, there were four cases of bacteremia (1.3% [95% CI, 0.4%-3%])  in the positive RVP group compared to 20 (11.4% [95% CI, 7.3%-16.7%]) in the negative RVP group. In the positive RVP group, there were 0 cases of meningitis (0% [95% CI, 0%-0.9%]) compared to 5 (2.8% [95% CI, 3.4%-85%]) in the RVP-negative group. The differences in bacteremia and meningitis rates between the two groups were statistically significant (P < .001).

Conclusion: Febrile infants ≤ 60 days of age with a positive RVP are associated with a significantly lower risk for SBI compared to those with a negative RVP, a 64% relative risk reduction. If validated with a prospective study, these findings could help guide clinical decision-making, potentially allowing for a more nuanced approach to the management and disposition of febrile infants, particularly the need for invasive workup and hospitalization.