The aquatic environments play a critical function in the widespread of antibiotic-resistant bacteria, ultimately impacting human health. We evaluated the abundance of Enterobacteriaceae and the various resistance gene determinants in final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, Republic of South Africa. A total of 44 presumptive Enterobacteriaceae was recovered following standard isolation methods. Upon molecular confirmation through Matrix-Assisted Laser Desorption/Ionization Time of flight (MALDI TOF), a high predominance of Klebsiella pneumoniae (24%) was noted. All the confirmed isolates (n=29) subjected to a panel of eighteen antibiotics categorized into eleven different classes were multidrug-resistant (MDR). They displayed resistance against antibiotics in more than three different classes. Notably, one E. cloacae exhibited resistance against all the antibiotics assayed. The multiple antibiotic resistance indices (MARI) ranged from 0.22 to 1.0, indicating an environment with high pressure of antibiotics. Conventional PCR analysis showed that 72.4% of the isolates harboured at least one β-lactamase genetic determinant. The most predominant extended-spectrum β-lactamases were blaCTX-M-group (21.5%), blaTEM (20%), and blaSHV (16.9%) while the most predominant plasmid-mediated AmpC-type β-lactamases were blaCIT and blaACC (25.9%) and blaEBC (22.2%). A total of 86.2% of the Enterobacteriaceae harboured a minimum of one non-β-lactam resistance gene determinant with predominance observed in catII (25%), sulII (15.8%), and sulI (14.5%). These results demonstrate an abundance of MDR Enterobacteriaceae in WWTPs' effluents. The study confirms the need to optimize current WWTPs' processes to improve the quality of effluents and ultimately reduce the potential risks of using such water when discharged into the environment.

中文翻译：

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从废水中回收的耐多药肠杆菌中编码 ESBL、pAmpC 和非 β-内酰胺抗性的基因的丰度

水生环境在抗生素抗性细菌的广泛传播中起着关键作用，最终影响人类健康。我们评估了南非共和国东开普省污水处理厂 (WWTP) 最终流出物中肠杆菌科细菌的丰度和各种抗性基因决定因素。按照标准分离方法共回收了 44 种推定的肠杆菌科细菌。通过基质辅助激光解吸/电离飞行时间 (MALDI TOF) 进行分子确认后，注意到肺炎克雷伯菌 (24%) 居高不下。所有经过 18 种抗生素处理的已确认分离株 (n=29) 被分为 11 种不同类别，均具有多重耐药性 (MDR)。他们对三种以上不同类别的抗生素表现出抗药性。尤其，一种 E. cloacae 对所有检测的抗生素表现出抗性。多重抗生素抗性指数 (MARI) 范围为 0.22 至 1.0，表明环境中抗生素压力较高。常规 PCR 分析表明，72.4% 的分离株含有至少一种 β-内酰胺酶遗传决定簇。最主要的超广谱 β-内酰胺酶是 blaCTX-M-组（21.5%）、blaTEM（20%）和 blaSHV（16.9%），而最主要的质粒介导的 AmpC 型 β-内酰胺酶是 blaCIT 和 blaACC（ 25.9%) 和 blaEBC (22.2%)。总共 86.2% 的肠杆菌科至少含有一种非 β-内酰胺抗性基因决定簇，在 catII (25%)、sulII (15.8%) 和 sulI (14.5%) 中观察到占优势。这些结果表明污水处理厂的流出物中含有大量 MDR 肠杆菌。