Changes in multidrug-resistant Enterobacteriaceae features among patients in the emergency room during the COVID-19...

The purpose of this study was to investigate stage-specific changes in risk factors and resistance patterns for multidrug-resistant Enterobacteriaceae (MDRE) bloodstream infections in emergency department (ED) patients during the COVID-19 Omicron wave. This retrospective cohort study focused on the ED of a tertiary care medical center in Taiwan from January 2022 to January 2023. Participants were adult ED patients (≥20 years) with positive blood cultures for Enterobacteriaceae and complete antimicrobial susceptibility testing (AST) data. Pandemic phases were defined using national surveillance data: Stage I (pre-peak), Stage II (epidemic peak), Stage III (post-peak). An exposome-wide association study identified stage-specific clinical and laboratory variables associated with MDRE infection. Resistance trends for key bacteria-antibiotic pairs were analyzed across stages. Of 1,269 screened ED patients, 816 met inclusion criteria; 287 (35.2%) had MDRE. In Stage I, age 75-85 years (OR 2.48, 95% CI 1.16-5.43) and ≥85 years (OR 2.29, 95% CI 1.07-5.00), along with RBC, Hb, and Hct, were associated with MDRE. In Stage II, platelet count (OR 1.00, 95% CI 1.00-1.01) and ALT (OR 1.00, 95% CI 0.99-1.00) were associated. In Stage III, WBC (OR 1.04, 95% CI 1.00-1.08), segmented neutrophils (OR 1.03, 95% CI 1.00-1.05), Hb, and Hct were associated. Klebsiella pneumoniae maintained 100% ampicillin resistance with rising ciprofloxacin resistance, while Escherichia coli showed declining resistance to multiple agents. In conclusion, MDRE-associated variables and resistance patterns varied across pandemic stages, supporting the need for dynamic, stage-adapted risk assessment and antimicrobial stewardship strategies in acute care settings.