Prior research has demonstrated that the bacteria in untreated and in treated municipal wastewater frequently harbor Class 1 integrons, which are genetic elements capable of incorporating exogenous genetic material into the genome and modulating the expression of these gene cassettes. Integrons, therefore, are believed to play an important role in the evolution of multiple antibiotic resistant bacteria. In this study, more than 300 bacterial strains were isolated using tetracycline-amended LB agar plates from the effluent of a municipal wastewater treatment facility and from the river to which this effluent is discharged. PCR targeting the integrase gene of class 1 integrons confirmed that bacteria in treated wastewater were likely to harbor a class 1 integron (102 out of 124 isolates) whereas none of the bacteria isolated from the river harbored a class 1 integron (~250 strains). All of these bacterial isolates were then tested for resistance to eight different antibiotics or groups of antibiotics (ciprofloxacin, sulfonamides, tetracycline, streptomycin, ampicillin, polymixin B, rifampicin and trimethoprim-sulfamethoxazole) using the Kirby-Bauer disc diffusion assay. Bacterial isolates originating in the wastewater treatment plant were, on average, less susceptible to 6 of the 8 antibiotics than a control. Similar results were observed for bacterial isolates originating from the river. These results suggest that although bacteria isolated from wastewater effluents are more likely to harbor a Class 1 integron, these bacteria are not more likely to be resistant to multiple antibiotics.

Integrons and multiple-antibiotic resistant bacteria in Minnesota surface waters

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.