Occurrence of multidrug-resistant Escherichia coli and antibiotic resistance genes in a wastewater treatment plant and its associated river water in Harare, Zimbabwe

IF 1 4区环境科学与生态学 Q4 WATER RESOURCES

Water SA Pub Date : 2023-10-27 DOI:10.17159/wsa/2023.v49.i4.4036

None Hilary Takawira, None Joshua Mbanga

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Abstract

Wastewater treatment plants (WWTPs) have been identified as point sources of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARG). Due to variations in antibiotic use and prescribing patterns in different countries, it is imperative to establish the presence of ARB and ARGs in water environments on a country-by-country basis. This study investigated the occurrence of 11 antibiotic-resistance genes (QNRB, DFR14, CTX-M, KPC, Sul1, QNRA, Sul2, ERMB, ERMA, SHV, NDM), and antibiotic-resistant Escherichia coli in a WWTP and its associated river water in Harare, Zimbabwe. 24 water samples were collected across 3 sites: upstream and downstream of the WWTP; final effluent of the WWTP. The samples were collected weekly for 8 weeks. Pure cultures of the E. coli isolates were obtained by membrane filtration (0.45 µm) and repeated streaking on Tryptone Bile X-glucuronide followed by biochemical tests (indole test; citrate test; motility, indole, and ornithine). Antibiotic resistance profiling was done for 12 antibiotics using the disc diffusion method. Total genomic DNA was extracted from the 21 water samples and the occurrence of 11 antibiotic-resistant genes investigated using conventional PCR. 86 E. coli isolates were obtained from the sampled sites: 28 from the upstream site, 26 from the WWTP effluent, and 32 from the downstream site. The results from chi-squared analysis showed a significant association (p < 0.05) between the sampling site and the percentage of antibiotic-resistant E. coli for all 12 antibiotics investigated. The percentage of E. coli isolates resistant to the tested antibiotics varied from 29% (ertapenem) to 80.2% (ciprofloxacin). 81 (94.2%) E. coli isolates were resistant to antibiotics from ≥3 classes. Eight (8/11, 72.7%) ARGs were detected in the WWTP effluent and river water samples. Results indicate that the investigated WWTP and associated river water are reservoirs of ARGs and antibiotic-resistant E. coli, which is a public health concern.

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在津巴布韦哈拉雷的一家污水处理厂及其相关河水中出现多重耐药大肠杆菌和抗生素耐药基因

污水处理厂(WWTPs)已被确定为耐药细菌(ARB)和耐药基因(ARG)的点源。由于不同国家的抗生素使用和处方模式存在差异，必须在各国的基础上确定水环境中是否存在ARB和ARGs。本研究对津巴布韦哈拉雷某污水处理厂及其相关河水中11个耐药基因(QNRB、DFR14、CTX-M、KPC、Sul1、QNRA、Sul2、ERMB、ERMA、SHV、NDM)和耐药大肠杆菌的发生情况进行了调查。污水处理厂的最终排出物。每周采集样本，连续8周。通过膜过滤(0.45µm)获得大肠杆菌分离物的纯培养物，并在Tryptone Bile X-glucuronide上反复染色，然后进行生化试验(吲哚试验;柠檬酸测试;运动性、吲哚和鸟氨酸)。采用圆盘扩散法对12种抗生素进行耐药性分析。从21份水样中提取总基因组DNA，并采用常规PCR方法调查11个耐药基因的发生情况。从采样地点分离出86株大肠杆菌:28株来自上游地点，26株来自污水处理厂排放物，32株来自下游地点。卡方分析结果显示显著相关(p <对所有12种抗生素的耐药大肠杆菌百分比与采样点之间的差异为0.05)。大肠杆菌分离株对所测抗生素耐药的百分比从29%(厄他培南)到80.2%(环丙沙星)不等。81株(94.2%)大肠杆菌对≥3类抗生素耐药。污水处理厂出水和河流水样共检出8种ARGs(8/11, 72.7%)。结果表明，所调查的污水处理厂及其相关河水是ARGs和耐药大肠杆菌的宿主，是一个公共卫生问题。

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来源期刊

Water SA 环境科学-水资源

CiteScore

2.80

自引率

6.70%

发文量

审稿时长

18-36 weeks

期刊介绍： WaterSA publishes refereed, original work in all branches of water science, technology and engineering. This includes water resources development; the hydrological cycle; surface hydrology; geohydrology and hydrometeorology; limnology; salinisation; treatment and management of municipal and industrial water and wastewater; treatment and disposal of sewage sludge; environmental pollution control; water quality and treatment; aquaculture in terms of its impact on the water resource; agricultural water science; etc. Water SA is the WRC’s accredited scientific journal which contains original research articles and review articles on all aspects of water science, technology, engineering and policy. Water SA has been in publication since 1975 and includes articles from both local and international authors. The journal is issued quarterly (4 editions per year).