Nationwide surveillance of carbapenem-resistant Gram-negative pathogens in the Lebanese environment.

Gram-negative ESKAPE pathogens with carbapenem resistance pose a significant health threat. Despite extensive research on the spread of these pathogens within Lebanese hospital settings, their emergence in environmental settings remains understudied. This study aimed to explore the environmental spread of carbapenem resistance among Gram-negative bacteria isolated from environmental samples in nine districts across Lebanon. A total of 250 samples were collected from wild animals, sewage, water, and soil between June 2022 and September 2023. Samples were streaked on MacConkey agar plates supplemented with 2 mg/L meropenem. Bacterial species were identified primarily using API20E. Antimicrobial susceptibility profiles were determined by the disk diffusion method and the Vitek 2 compact system. Meropenem-resistant Gram-negative bacteria were further characterized by whole-genome sequencing, and each of the bacterial species, sequence types, resistance genes, and plasmids was detected by sequence data analysis. We successfully isolated 130 carbapenem-resistant isolates from various samples, 67 of which belonged to the ESKAPE pathogens list and showed a multidrug-resistant (MDR) profile. The distribution of the latter was as follows: Escherichia coli (65.67%), Acinetobacter baumannii (16.42%), Pseudomonas aeruginosa (11.94%), and Klebsiella pneumoniae (5.97%). Several carbapenem resistance genes were detected, with a prevalence of blaNDM-5 in Escherichia coli and Klebsiella pneumoniae, blaIMP-1 and mexAB-OprM efflux pumps in Pseudomonas aeruginosa, and blaOXA-23 in Acinetobacter baumannii. Our findings revealed a widespread distribution of carbapenem-resistant ESKAPE bacteria in Lebanon, underscoring the significant public health risk posed by these pathogens. This highlights the urgent need to address the dissemination of antibiotic resistance in Lebanese environmental settings.

Importance: The emergence of antimicrobial resistance (AMR) extremely burdens public health and increases morbid and mortal threats in Lebanon. While the majority of the studies in our country target antimicrobial resistance in clinical settings, fewer studies focus on antimicrobial resistance dissemination in the environment. The significance of our research is that it sheds light on the environment as a less explored yet equally crucial sector in the spread of AMR. Here, we isolated carbapenemase-producing bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii) that were categorized as multidrug resistant (MDR) from diverse environmental sources in multiple provinces across Lebanon. The finding of carbapenem-resistant bacteria carrying plasmids represents a potential risk due to the possible spread of resistance genes via horizontal gene transfer across the environment and hospital settings. This highly recommends the implementation of regular surveillance to monitor the spread of antimicrobial resistance among environmental bacteria, which consequently leads to its spread within communities and thus poses a great threat to human health.