Antimicrobial resistance evolution over time during pre-and post-COVID-19 periods at a major tertiary care center in Lebanon

Introduction: The increasing rates of AMR have been tolling the healthcare systems globally. This study aims to explore the evolution of AMR patterns against commonly encountered clinical bacterial pathogens at a major tertiary care center in Lebanon during pre-COVID (2019) and post-COVID (2023) periods. Methodology: Consecutive non-duplicate isolates of Gram-positive (e.g., Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus spp.) and Gram-negative pathogens (e.g., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii) were analyzed using MALDI-TOF identification and CLSI-standardized disk diffusion/Etest methods. Results: Key findings revealed persistent methicillin-resistant S. aureus (MRSA) rates (36%), increased vancomycin-resistant Enterococci (VRE; 7% to 10%), and high penicillin susceptibility among S. pneumoniae. Gram-negative isolates exhibited concerning trends: ESBL prevalence rose in E. coli (32% to 36%) but remained stable (35% to 34%) in K. pneumoniae. Carbapenem-resistant Enterobacterales (CRE) rates remained unchanged for E. coli (6% to 5%) but declined for K. pneumoniae (15% to 6%). A. baumannii susceptibility remained critically low (18–55%), while P. aeruginosa showed stable susceptibility (76–92%). Conclusions: An overall increase in the resistance profiles among different bacterial species is noted in comparison with earlier studies from this institution. These findings align with prior multidrug-resistant strains and underscore the need for robust surveillance, antibiotic stewardship, and infection control measures.