Quantitation of antibiotic resistance genes pollution in hospital waste water effluent and Urban Clinton River Water, Michigan, USA

Abstract

Hospitals are the major antibiotic consumers and thus facilitate the spread of antibiotic resistance. Hospital wastewaters definitely play an important role in the evolution and dissemination of antibiotic-resistant genes. In this study, we evaluated the occurrence of three common groups of extended spectrum beta lactamase (ESBL) and their resistance genes in the hospital effluent and urban river as possible sources. A total of 156 bacteria were isolated from upstream and downstream of hospital waste-water treatment plant. Waste water samples were analyzed for the copy number of three groups of ESBL; SHV, TEM and CTX-M-1 genes. The bacteria isolated were approximately 40–65% resistant to cefotaxime, 25–40% to chloramphenicol, 30–40% to tetracycline, 25–65% to ciprofloxacin and finally 30–50% to gentamicin. Of these 156 bacteria, 34 (22%) were found to be ESBL producing bacteria. The copy numbers1 are 102, 104 and 103, respectively. Based on the data, the abundance of blaSHV and blaCTX-M-1 remained similar in both populations whereas the quantity of blaTEM decreased to an order of 102 in Urban Clinton River Water (UCRW). Hospital effluent and urban rivers are potential routes for dissemination of ESBL producing bacteria and their respective genes into the natural environment and pose a hazard to environmental and public health.