Impact of antimicrobial stewardship in organisms causing nosocomial infection among COVID-19 critically ill adults

Objective: To evaluate the implementation of an antibiotic stewardship program in critically ill COVID-19 patients and to establish risk factors for coinfection. Secondary objective was to analyze the evolution of the etiology of respiratory nosocomial infections. Methods: Single-center observational cohort study of consecutive patients admitted to ICU due to COVID-19 pneumonia from March 2020 to October 2022. An antibiotic stewardship program was implemented at the end of the second wave. Results: A total of 878 patients were included during 6 pandemic waves. Empirical antibiotic consumption decreased from the 96% of the patients during the first pandemic wave, mainly in combination (90%) to the 30% of the patients in the 6th pandemic wave most in monotherapy (90%). There were not differences in ICU and Hospital mortality between the different pandemic periods. In multivariate analysis, SOFA at admission was the only independent risk factor for coinfection in critically ill COVID-19 patients (OR 1,23 95%CI 1,14 to 1,35). Differences in bacterial etiology of first nosocomial respiratory infection were observed. There was a progressive reduction in Enterobacteriaceae and non- fermentative Gram Negative Bacilli as responsible pathogens, while methicillin-sensitive Staphylococcus aureus increased during pandemic waves. In the last wave, however, a trend to increase of potentially resistant pathogens was observed. Conclusions: Implementation of an antibiotic stewardship program was safe and not associated with worse clinical outcomes, being severity at admission the main risk factor for bacterial coinfection in covid-19 patients. A decline in potentially resistant pathogens was documented throughout the pandemic.