Changes in Respiratory Microorganism Distribution and Antimicrobial Resistance Patterns in Intensive Care Units: A Comparative Analysis Before and During the COVID-19 Pandemic

This study aimed to evaluate changes in the distribution of microorganisms isolated from respiratory tract specimens and antimicrobial resistance patterns in intensive care units (ICUs) before and during the COVID-19 pandemic. Microbiological data from respiratory tract specimens obtained from patients admitted to the ICUs of a state hospital between January 1, 2019, and April 30, 2021, were retrospectively reviewed. The study period was divided into the pre-pandemic period (January 1, 2019–February 29, 2020) and the pandemic period (March 1, 2020–April 30, 2021). A total of 634 patients and 757 respiratory tract isolates were included. The median age was 79 years (IQR: 66–85), and 55.2% of the patients were male. Acinetobacter spp. was the most frequently isolated microorganism overall, followed by Klebsiella spp., Pseudomonas spp., Escherichia coli, and Staphylococcus aureus. Overall microorganism distribution differed significantly between the pre-pandemic and pandemic periods (p<0.001). Antimicrobial resistance analyses were performed for the most frequently isolated bacterial pathogens. No significant changes were observed in resistance rates among Pseudomonas spp. isolates. Among Acinetobacter spp. isolates, trimethoprim-sulfamethoxazole resistance increased significantly during the pandemic period. Among Klebsiella spp. isolates, trimethoprim-sulfamethoxazole resistance increased significantly. These findings indicate that the COVID-19 pandemic period was associated with changes in respiratory microorganism distribution and selected antimicrobial resistance patterns in ICUs.