Impact of antibiotic therapy in patients with respiratory viral infections: a retrospective cohort study.

Objectives: The impact of antibiotics in patients with positive polymerase chain reaction (PCR) for respiratory viruses without evidence of a respiratory bacterial co-infection is largely unknown. The aim of this study was to assess the association of antibiotics on 30-day mortality and length of hospital stay in patients with an acute respiratory infection and PCR documented presence of respiratory viruses.

Methods: We conducted a retrospective cohort study of adult patients admitted to hospital between 2012 and 2021 with positive PCR for influenza virus (H3N2, H1N1, influenza B), respiratory syncytial virus, human metapneumovirus or severe acute respiratory syndrome coronavirus 2. We used logistic regression, the Kaplan-Meier estimator and Poisson's regression to assess the impact of antibiotic therapy on outcomes.

Results: Among 3979 patients, 67.7% received antibiotics. In adjusted analyses, antibiotics initiated in the emergency department (adjusted OR 1.23, 95% CI 0.77-1.96) and days of antibiotic therapy (adjusted OR per day of therapy 0.98, 95% CI 0.95-1.00) had no significant impact on mortality, whereas antibiotics initiated later during admission (adjusted OR 2.25, 95% CI 1.26-4.02) was associated with increased mortality. Patients prescribed antibiotics had longer duration of hospital admission.

Conclusions: We observed no protective association between in-hospital antibiotic therapy and outcomes, suggesting overuse of antibiotics in respiratory infections with proven respiratory viruses. A restrictive antibiotic strategy may be warranted.