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Characterization of Antibiotic Resistance Genes and Bacteria in a Municipal Water Resource Recovery Facility Publisher Pubmed



Rajabi A1 ; Farajzadeh D2 ; Dehghanzadeh R1, 3 ; Aslani H1, 3 ; Mousavi S4 ; Mosaferi M1, 3 ; Dehghani MH5 ; Asghari FB6
Authors
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Authors Affiliations
  1. 1. Department of Environmental Health Engineering, Faculty of Health, Tabriz University of Medical Sciences, Tabriz, Iran
  2. 2. Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Azarbaijan Shahid Madani University, Tabriz, Iran
  3. 3. Health and Environment Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
  4. 4. Department of Statistics and Epidemiology, Tabriz University of Medical Sciences, Tabriz, Iran
  5. 5. Institute for Environmental Research, Center for Solid Waste Research, Tehran University of Medical Sciences, Tehran, Iran
  6. 6. Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran

Source: Water Environment Research Published:2022


Abstract

Municipal water resource recovery facilities (WRRFs) are important sources of antibiotic-resistant bacteria and genes (ARB and ARGs). In this study, antibiotic-resistant total heterotrophic bacteria (THBR) counts (CFU/ml) cultivated from influent, effluent of activated sludge process, and outflow of disinfection unit of an urban WRRF were investigated for the presence of 16, 32, 64, and 128 μg/ml of nine antibiotics. The isolates of Pseudomonas spp., Acinetobacter spp., and Escherichia coli obtained from effluent of activated sludge process were subjected for molecular identification by detecting the 16S rRNA gene sequences. Additionally, using the polymerase chain reaction method (PCR), the isolates were investigated for the presence of blaSHV, blaTEM, blaCTX-M, blaVIM, sul1, and qnrS genes. According to the results, the abundance of THBR counts was not significantly reduced by the biological treatment except for cefixime and sulfamethoxazole; it also increased for some antibiotics after disinfection unit. The average removal efficiency of THBR resistant to ciprofloxacin, sulfamethoxazole, and ceftazidime were 7.9 ± 1.7%, 41.8 ± 2.1%, and 14.4 ± 6.2%, respectively. Also, all the tested isolates were resistant to at least four antibiotics. For all antibiotics, the resistance ratio (THBR/THB) significantly increased in the effluent and after chlorination unit. Among 12 resistant isolates, blaTEM and sul1 genes were the most frequently detected ones involved in 92% and 83% of the isolates, respectively. Both blaTEM and sul1 genes were found in 100% of E. coli, and 83% and 67% of Pseudomonas spp. isolates, respectively. Further efforts are necessary to limit the transmission of ARB and ARGs from WRRFs into the environment and prevent human health threats. Practitioner Points: The ratio of resistance significantly increased after biological treatment. Up to 40% of heterotrophic bacteria in the effluent was antibiotic resistant. blaTEM and sul1 genes were more prevalent (92%) in all isolates of bacteria. Both blaTEM and sul1 genes were found in 100% of E. coli isolates. Pseudomonas spp. holds blaTEM and sul1 genes in 83% and 67% of isolates, respectively. © 2022 Water Environment Federation.