It is very significant to assess the distribution of natural plasmid-harboring bacteria that are resistant to antibiotics, to characterize their plasmids and to evaluate the frequency of R plasmids in E. coli population in aquatic systems especially in drinking water in which its presence predict that the water might be contaminated.

          In this study, isolated resistant strains of E. coli  were detected in both Lake Ontario water and drinking water. The data show that the use and misuse of antibiotics have resulted in increasing in the rate of resistant E. coli strains to ampicillin, kanamycin and azithromycin in aquatic environments. The AR plasmids in E. coli colonies isolated from drinking water cause major anxiety to the public because its presence signifies a possible pubic health risk. The most frequent rate of resistance in E. coli cells in drinking water and Lake Ontario water samples were ampicillin, kanamycin and azithromycin respectively. Higher number of E. coli colonies resistant to antibiotics was obtained from Lake Ontario compared to the one obtained from drinking water samples. This increase in the incidence of antibiotic resistant bacteria in both cases could be due to the wide use of antibiotics in human, agriculture, poultry, and in veterinary medicine [6, 1].