Risk Factors of Secondary Bacterial Infection in Patients Hospitalized with COVID-19

Background/Objectives: Secondary bacterial infections in subjects hospitalized with COVID-19 are associated with longer hospital stays and an increased risk of death. Thus, identifying the risk factors associated with bacterial complications in patients with SARS-CoV-2 infection is clinically important. Methods: We analysed the collected records of all adult patients diagnosed with an acute COVID-19 infection who were admitted to the Hospital for Infectious Diseases in Warsaw, Poland, between March 2020 and November 2021. Logistic regression models were used to identify factors associated with bacterial infections complicating the SARS-CoV-2 course. Results: The records of 1963 patients were analysed; 1128 (57.4%) of the patients were male, the median age of the cohort was 63 years (IQR: 50–74 years), and 202 patients (10%) died. A bacterial infection complicating the course of COVID-19 was diagnosed in 351 (18%) patients. In a multivariate logistic regression model the only factors identified as independently associated with an increased odds of bacterial infection were age (OR per decade: 1.21, p = 0.016), length of hospitalization (OR per day: 1.12, p < 0.001), and D-dimer concentration (OR per 500 units: 1.01, p = 0.048). Conclusions: Shortening the length of hospitalization of patients with COVID-19 can reduce the risk of bacterial infection complications, especially in elderly individuals. Coagulation system activation in COVID-19 patients increases the risk of a bacterial infection.