Tetracycline resistance of Escherichia coli isolated from water, human stool, and fish gills from the Lake Sevan basin.

The ecological state of Lake Sevan, the largest drinking water reservoir for the South Caucasus, formed under the influence of climatic and social changes. This study assesses the bacteriological quality of water in the rivers of the Lake Sevan basin and tetracycline-resistant bacteria isolated from fish and people living near the rivers of the Lake Sevan basin in Armenia in autumn 2019 and spring 2020. No differences have been shown for the tetracycline resistance of the investigated E. coli isolated from the human gut and the Masrik, Argichi, and Gavaraget Rivers. Horizontal gel electrophoresis revealed the same plasmid bands in most of the investigated E. coli with the same tetracycline resistance from the different sources of the Argichi River (obtained from people/fish/water sources where the fish were caught). The results also showed that most of the waters carried Edwardsiella spp., Erwinia spp., Morganella spp., and Proteus spp. in addition to E. coli; the coliform index did not exceed the standard level of 5 × 104 CFU mL-1 there. These findings highlight the importance of multidisciplinary studies of bacteria from "interacting" ecosystems, which might serve as a basis for the suggestion of microbial antibiotic resistance as another indicator of water pollution.