THE DIVERSITY OF MICROBES RESISTANT TO TWO CLINICALLY USED ANTIBIOTICS, VANCOMYCIN AND COLISTIN, IN NATURAL WATERS

The misuse and overuse of antibiotics in both clinical and agricultural settings has led to an increase in bacteria resistant to multiple antibiotics. Antibiotics of last resort, such as colistin and vancomycin, are now being deployed to combat the potent threats of antibiotic resistant microbes. Hotspots for antibiotic resistance, including multidrug resistance, in natural environments remain largely unstudied and require further elucidation. To identify bacteria resistant to two last-resort antibiotics, samples were taken from four types of freshwater habitats including agricultural waters, natural waterways, commercial drains, and wastewaters and grown in the presence of vancomycin and colistin. The microbial communities from these selected communities were then compared to microbial communities grown in the absence of selection. All sites had a great deal of diversity, even in the presence of colistin and vancomycin. Notably, samples found in agricultural waters and drains had a high species diversity compared to natural and wastewaters. One genus, Ochrobactrum, dominated across all habitats and in both selected and non-selected communities. This genus contains several emerging opportunistic pathogens. Overall we conclude that resistance to last-line antibiotics is prevalent in many freshwater habitats in the natural environment.