The dissemination of antimicrobial resistance determinants in surface water sources in Lebanon

The prevalence of antibiotic-resistant bacteria in surface water in Lebanon is a growing concern and understanding the mechanisms of the spread of resistance determinants is essential. We aimed at studying the occurrence of resistant bacteria and determinants in surface water sources in Lebanon and understanding their mobilization and transmission. Water samples were collected from five major rivers in Lebanon. A total of 91 isolates were recovered by incubating at 37 degrees C on Blood and MacConkey agar out of which 25 were multi-drug resistant (MDR) and accordingly were further characterized. Escherichia coli and Klebsiella prieumoniae were the most common identified MDR isolates. Conjugation assays coupled with in silica plasmid analysis were performed and validated using PCR-based replicon typing (PBRT) to identify and confirm incompatibility groups and the localization of beta-lactamase encoding genes. Escherichia coli EC23 carried a bla(NDM-5) gene on a conjugative, multireplicon plasmid, while bla(CTX-M-15) and bla(TEM-1B) were detected in the majority of the MDR isolates. Different sequence types (STS)were identified including the highly virulent E. coli ST131. Our results showed a common occurrence of bacterial contaminants in surface water and an increase in the risk for the dissemination of resistance determinants exacerbated with the ongoing intensified population mobility in Lebanon and the widespread lack of wastewater treatment.