Associations between antibiotic use and outcomes in patients hospitalized with community-acquired pneumonia and positive respiratory viral assays

Background Newly released community-acquired pneumonia (CAP) guidelines include a conditional recommendation to treat all hospitalized patients with positive respiratory virus assays with antibacterials. We assessed the frequency, duration, and outcomes of antibacterial prescribing in this population. Methods We retrospectively identified all hospitalized patients with possible CAP and a positive respiratory virus test at five hospitals, June 2015-December 2024. We used detailed clinical data to propensity-weight patients treated with 0-2 vs 5-7 days of antibacterials and compared outcomes overall and for different viruses. Results Among 6779 patients with possible CAP and a respiratory virus, 3269 were treated with 0-2 days and 1560 with 5-7 days of antibacterials. After propensity-weighting 2614 patients (1720 treated 0-2 days, 894 treated 5-7 days), there were no significant differences in hospital length of stay (11.7 days vs 11.1 days; OR 1.05, 95% CI 0.97-1.15), ICU admission after 48 hours (28.3% vs 28.2%; OR 1.01, 95% CI 0.86-1.18), in-hospital mortality (9.5% vs 9.8%; OR 0.97, 95% CI 0.74-1.27), or 30-day hospital-free days (16.9 days vs 17.0 days; OR 0.99, 95% CI 0.95-1.03). Results were consistent when restricted to non-SARS-CoV-2 viruses and to influenza alone, when comparing 0 vs 5-7 days of antibacterials, and when restricting to patients with ICD-10 codes for pneumonia present on admission. Conclusions Antibacterial use for patients with possible CAP and respiratory viruses is highly variable but outcomes are similar with 0-2 vs 5-7 days of antibacterials. This suggests antibiotics are not beneficial in most CAP patients who test positive for respiratory viruses.