The impact of the COVID-19 pandemic on Gram-negative bacteria susceptibility patterns in respiratory samples of intensive care units in the Brussels Capital Region, 2010-2021

Background: The effect of the Coronavirus Disease 2019 (COVID-19) pandemic on gram-negative bacteria nonsusceptibility to antibiotics is unclear. Methods: Between January 1, 2010, and December 31, 2021, the respiratory samples of intensive care unit patients at 3 University Hospitals in Brussels were retrieved. Based on the nonsusceptibility to antimicrobial classes, drug-resistance patterns were defined as multi-drug-resistant, extensively drug-resistant, and pan-drug-resistant. The study time frame was divided into 6 periods of 2 years each, and the impact of the COVID-19 pandemic (last period: 2020-2021) was assessed. Results: During the current study, 10,577 samples were identified from 5,889 patients. While a significant augmentation of multi-drug-resistant isolates was noticed once comparing 2 prepandemic periods (2012-2013 and 2014-2015), all 3 patterns of nonsusceptibility significantly increased, comparing the years before and throughout the COVID-19 pandemic (2018-2019 and 2020-2021). Globally, the greatest increase in antimicrobial nonsusceptibility, comparing the last 2 periods, was reported for piperacillin-tazobactam (from 28% to 38%). Pseudomonas aeruginosa was the most isolated species, and the most involved in the appearance of resistance, with an augmentation of nonsusceptibility percentage to meropenem of 22% (from 25% to 47%), between the prepandemic and the pandemic periods. Conclusions: The COVID-19 pandemic was associated with increasing trends of antimicrobial resistance in respiratory samples of patients admitted to the intensive care units in university hospitals with well-implemented antibiotic stewardship programs.