Department of Aquatic Animal Health Management, Kerala University of Fisheries and Ocean Studies, Kochi, Kerala, India.
State Laboratory for Livestock, Marine & Agri Products (SLMAP), Department of Animal Husbandry, Government of Kerala, India.
Sci Total Environ. 2020 Dec 15;748:141538. doi: 10.1016/j.scitotenv.2020.141538. Epub 2020 Aug 6.
Quinolones are one of the most important classes of antibacterials available for the treatment of infectious diseases in humans. However, there is a growing concern about bacterial resistance to antimicrobials including quinolones. The spread of antibiotic-resistant bacteria in the aquatic environment has been recognized as a growing threat to public health and hospitals appear to be a major contributor to this. The objective of this study was to investigate the prevalence of quinolone resistance in Escherichia coli from selected water bodies receiving direct hospital effluents in Kerala, India. Standard disc diffusion and E-test were used for antibiotic susceptibility testing. As antibiotic resistance can develop in bacterial isolates by different means, EtBr Agar Cartwheel method was used to detect the efflux pump activity and presence of resistant genes was detected by PCR. The mechanism of transfer of plasmid mediated resistance was confirmed by conjugation experiments. A total of 209 multidrug-resistant Escherichia coli were isolated from different hospital effluent discharge sites and aquaculture farms located in their vicinity. Among them, qnrB was found to be most prevalent followed by qnrS, OqxAB, qnrA and aac (6')-Ib-cr. The results suggested that the antibiotics present at sub-inhibitory concentrations in direct hospital effluents increases the selection pressure impacting the cell function of even normal microorganisms in the aquatic environment to change the genetic expression of virulence factors or acquire resistance genes by different transfer mechanisms, posing a serious threat to public health.
喹诺酮类药物是治疗人类感染性疾病最有效的抗菌药物之一。然而，人们越来越担心包括喹诺酮类药物在内的抗菌药物的细菌耐药性。抗生素耐药细菌在水生环境中的传播已被认为是对公众健康的一个日益严重的威胁，而医院似乎是造成这种情况的主要原因之一。本研究的目的是调查在印度喀拉拉邦直接接受医院污水的选定水体中，大肠杆菌对喹诺酮类药物耐药的流行情况。采用标准圆盘扩散法和 E 试验进行抗生素药敏试验。由于细菌分离株可以通过不同的方式产生抗生素耐药性，因此采用 EtBr 琼脂车轮法检测外排泵活性，并通过 PCR 检测耐药基因的存在。通过接合实验证实了质粒介导耐药性的转移机制。从不同的医院污水排放点和附近的水产养殖场共分离出 209 株多药耐药性大肠杆菌。其中，qnrB 最为常见，其次是 qnrS、OqxAB、qnrA 和 aac（6'）-Ib-cr。结果表明，直接医院污水中存在亚抑菌浓度的抗生素会增加选择压力，即使在水生环境中的正常微生物的细胞功能也会受到影响，从而改变毒力因子的遗传表达或通过不同的转移机制获得耐药基因，这对公众健康构成了严重威胁。
