Presence of antibiotic resistant bacteria and antibiotic resistance genes in raw source water and treated drinking water

摘要

Antibiotic resistance is becoming a very large problem throughout the world. The spread of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment is a major public health issue. Aquatic ecosystem is a significant source for ARB and ARGs. The drinking water treatment system is designed specifically to eliminate bacteria and pathogens in drinking water. The presence of ARB and ARGs in source water and drinking water may affect public health and it is an emerging issue in drinking water industry. Therefore, this study was conducted to study the presence of ARB and ARGs in a source water, treated drinking water (finished water), and in the distribution line (tap water) in a rural water treatment plant in Louisiana. The results showed the presence of several ARB in the source water including, Enterobacter cloacae, Klebsiella pneumoniae, Escherichia coli, Pseudomonas, Enterococcus, Staphylococcus and Bacillus spp. However, the water treatment plant effectively removed these bacteria in the treated water as none of these bacteria were found in the tap water as well as in the finished water at the water treatment plant. Bacterial DNA including 16s rRNA and ARGs of sulfonamides and tetracycline antibiotics were observed in raw water. The presence of 16s rRNA was found consistently in every month of sampling in raw water, finished water, and tap water. This suggests that the filtration system at the treatment plant was ineffective in filtering out small fragments of bacterial DNA. Also, the possibility of the presence of biofilms in the water pipeline exists, which may develop antibiotic resistance due to the selective pressure of chlorination in drinking water. (C) 2015 Elsevier Ltd. All rights reserved.