Detection of the phenotypic and genotypic characteristics of antibiotic and chlorine resistance Escherichia coli isolates from municipal and industrial wastewaters

Escherichia coli (E. coli) strains in the gut of human harbor wide range of antibiotic resistance genes. Studying resistance determinants in E. coli at the genetic level is very important for understanding and possibly controlling the resistance. Treated wastewater discharged from municipal and some industrial (poultry and livestock slaughterhouse) wastewater treatment plants (WWTPs) are an important contamination source of antibiotic resistance, threatening the environment safety of receiving waters. E. coli isolates resistant to ampicillin, chloramphenicol and tetracycline was monitored in three WWTPs. The presence of ESBL genes were detected by PCR. Among β-lactam antibiotics, antibiotic group carbapenem showed the highest sensitivity. Accordingly, 99 % sensitivity was observed to imipenem, ertapenem and doripenem antibiotics. Sensitivity to meropenem was 100 %. 91.9 % of the isolates had tetA gene (encoding resistance to tetracycline). 55 % of the isolates were resistant to tetracycline. Based on the PCR results, in 53 % of tetracycline resistant isolates, tetA gene was observed. Among these, 24, 17 and 12 isolates were observed in poultry slaughterhouse, municipal and livestock slaughterhouse wastewaters, respectively. Among all isolates resistant to tetracycline from poultry slaughterhouse and livestock slaughterhouse wastewaters, only one had no tetA. Gene tetA was found in all isolates in municipal wastewater.