ANALYSIS OF THE DISTRIBUTION OF ANTIBIOTIC-RESISTANT BACTERIA IN THE WATER OF THE MURATSAI RESERVOIR

Abstract

Antibiotic resistance of microorganisms in aquatic ecosystems is one of the most pressing environmental and biomedical challenges of modern times. Aquatic environments act as significant reservoirs for the accumulation and dissemination of antibiotic-resistant bacteria due to the extensive use of antimicrobial agents in human medicine, livestock production, and agriculture. The aim of this study was to assess the distribution and biological characteristics of antibiotic-resistant bacteria in the water of the Muratsai Reservoir (West Kazakhstan Region). Water samples were collected from surface and bottom layers at sites with the highest anthropogenic impact. Bacteriological analysis included cultivation of microorganisms on Luria–Bertani medium, examination of morphological and physiological-biochemical characteristics, and determination of antibiotic susceptibility using the disk diffusion method. In addition, total DNA was extracted from the isolated strains and visualized by agarose gel electrophoresis to confirm the suitability of the samples for molecular genetic studies. The results revealed Gram-negative, motile, oxidase-positive mesophilic bacteria exhibiting resistance to several β-lactam antibiotics and displaying features of multidrug resistance. Fluoroquinolones and amphenicols demonstrated the highest antibacterial activity, whereas penicillins and cephalosporins were the least effective. The findings indicate significant anthropogenic pressure on the reservoir and highlight the importance of continuous monitoring of antibiotic-resistant bacteria in surface water bodies to ensure environmental safety and public health protection.