Phylogenetic group distribution and antibiotic resistance of isolates in aquatic environments of a highly populated area.

Background: Extended-spectrum beta-lactamase (ESBL)-producing including (), are recognized as a global public health threat due to their multidrug-resistant (MDR) phenotypes and their rapid dissemination in aquatic environments. Nevertheless, studies investigating the prevalence and antimicrobial resistance (AMR) profile of ESBL-producing in Lebanese surface water are limited.

Objective: This study aimed to assess the physicochemical properties and microbial contamination load and to determine the distribution of AMR patterns of ESBL-producing in surface water samples from different sites in the North Governorate of Lebanon.

Methods: Water samples were collected from 25 major sites in North Lebanon. These samples were analyzed for the presence of total coliforms, , and fecal enterococci. Phenotypic and genetic characterizations were then performed for isolates to determine their resistance patterns and phylogenetic groups.

Results: Fifty-six samples out of 100 samples were positive for ESBL-producing , mostly harboring bla (40/56, 71%) including bla (33/40, 82%), bla gene (36/56, 64%), bla (20/56, 36%), and bla (16/56, 29%) including bla gene (11/16, 69%). Most ESBL-producing isolates belonged to the extra-intestinal pathogenic phylogroup B2 (40/56, 71.4%) while 10/56 (17.9%) belonged to the commensal phylogroup A.

Conclusion: Our results highlight the need to implement effective water monitoring strategies to control transmission of ESBL-producing in surface water and thus reduce the burden on human and animal health.