Isolation of Vancomycin Resistant Enterococci from Hospital Sewage in Tehran. 2016

Members of the genus Enterococcus are well-documented pathogens associated with various clinical manifestations, including bacteremia, infective endocarditis, intra-abdominal infections, urinary tract infections, and, in rare cases, central nervous system infections. In this study, we aimed to isolate vancomycin resistant enterococci from hospital sewage in Tehran. During 2016, sampling was carried out from effluent of a hospital in Tehran. The sewage sample was diluted and filtered using saline and membranes were transferred onto m-Enterococcus agar plates supplemented with vancomycin and incubated at 37°C. All colonies were identified at the species level using specific primers and the resistance of different strains to vancomycin and teicoplanin was determined. The presence of 9 different vancomycin resistance genes was detected using PCR. A total of 92 enterococcus isolates consisting of E. faecium (80%), E. faecalis (17%) and E. gallinarum (3%) were collected. All strains showed resistance to vancomycin and teicoplanin discs and the minimum inhibitory concentration ranges of vancomycin varied from 2048 to128 μg/ml and most of the isolates (82%) showed resistance to highest level of vancomycin. Three different vanA, vanB and vanC genes were detected and vanA gene was common among all vancomycin resistant strains. Moreover, the presence of vanC gene was limited to E. gallinarum strains. The presence of vancomycin and teicoplanin resistant strains in the effluent of this hospital in Tehran indicating the inefficiency of sewage treatment system.