Secondary bacterial infection in COVID-19 patients is a stronger predictor for death compared to influenza patients

Abstract

Secondary bacterial infections are a potentially fatal complication of influenza infection. We aimed to define the impact of secondary bacterial infections on the clinical course and mortality in coronavirus disease 2019 (COVID-19) patients by comparison with influenza patients. COVID-19 (n = 642) and influenza (n = 742) patients, admitted to a large tertiary center in Israel and for whom blood or sputum culture had been taken were selected for this study. Bacterial culture results, clinical parameters, and death rates were compared. COVID-19 patients had higher rates of bacterial infections than influenza patients (12.6% vs. 8.7%). Notably, the time from admission to bacterial growth was longer in COVID-19 compared to influenza patients (4 (1-8) vs. 1 (1-3) days). Late infections (> 48 h after admission) with gram-positive bacteria were more common in COVID-19 patients (28% vs. 9.5%). Secondary infection was associated with a higher risk of death in both patient groups 2.7-fold (1.22-5.83) for COVID-19, and 3.09-fold (1.11-7.38) for Influenza). The association with death remained significant upon adjustment to age and clinical parameters in COVID-19 but not in influenza infection. Secondary bacterial infection is a notable complication associated with worse outcomes in COVID-19 than influenza patients. Careful surveillance and prompt antibiotic treatment may benefit selected patients.

Figure 1

Multivariate analysis of various parameters related to disease severity and their association with death. For each viral infection, the odds ratios (OR) for each parameter and 95% confidence intervals (CI) are plotted.

Figure 2

Association of coinfection variables with disease outcome. Stacked graphs are presenting the percentage of surviving or non-surviving coinfected patients in both groups. The top graphs compare survival rates in each group according to the time of infection, while the lower graphs compare the survival rates according to the number of infections. Chi-Square Test was used to compare the categorical variables, ***, p < 0.001.