Microbial Assessment and Antibiotic Resistance Profiling of Bacterial Isolates from Surface Water of Poondi Lake, Tamil Nadu, India

The present study aims to assess the antibiotic resistance of bacterial isolates from the Poondi Lake, Tamil Nadu. The collected surface water samples were subjected to enumeration of Total Viable Count (TVC) on nutrient agar medium. The bacterial load ranged from 3.66 to 4.01 x 109 CFU/ml. Further, four dominant and morphologically distinct colonies were purified by quadrant streaking and biochemically analyzed to identify the bacteria. On analysis, Klebsiella spp., Pseudomonas spp., Escherichia spp., and Staphylococcus spp. were detected to be more prevalent. Then, an Antimicrobial Susceptibility Test (AST) was performed on bacterial isolates using the Kirby-Bauer disc diffusion method with ten commonly used antibiotics across Tamil Nadu. Among the tested isolates, Klebsiella, Escherichia, and Staphylococcus were found to be superbugs showing Multi-Drug Resistance (MDR). Increased resistance was observed towards β-lactams, fluoroquinolones, and tetracyclines, while aminoglycosides showed powerful effects against bacteria. Resistance towards old as well as last-resort antibiotics leads to accumulation and emergence of MDR microorganisms in the environment. Presence of such Antibiotic-Resistant Bacteria (ARB) in drinking water may contribute to the spread of hard-to-treat infections. Thus, the findings highlight the presence of ARB, emphasizing the need for pollution prevention and continuous monitoring of inland water bodies.