Abstract

Antibiotic resistance is currently one of the most serious challenges to global health and socio-economic development. New resistance mechanisms are arising and spreading throughout the world, posing a danger to our ability to treat common infectious diseases. Antibiotics are released into the environment mostly through wastewater treatment plants. Antibiotics’ presence may favour the selection of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). ARBs were isolated from a treated municipal wastewater sample. The resistant bacteria which were morphologically different and more in numbers were tested for multiple drug resistance. Two colonies were found to be resistant to the antibiotics, ampicillin, erythromycin, rifampicin, and chloramphenicol. These bacterial colonies were identified as Scandinavium goeteborgense CCUG 66741 and Aeromonas veronii CRC6 using 16S rRNA gene sequencing. These bacteria were also found to be sources of high-risk contamination with Multiple Antibiotic Resistance (MAR) Index of 0.6. They are not only multiple drug-resistant but human and animal pathogens. Further, they were evaluated for inhibition by nanocomposites (Ag⁰NP@GO and Ag⁰NP@rGO) at 500 mg/L using the agar well diffusion method. Both the bacteria were inhibited by the nanocomposites, showing a significant clearing zone with more inhibition caused by Ag⁰NP@rGO. Overall, the antibacterial action of the synthesized nanocomposite can be probably explained as the “Trap and Kill” mechanism. In particular, GO nanosheet with 2D structure and surface functional groups and charges help to bind the bacterial cells like a trapping agent whereas, silver nanoparticles embedded in GO sheet inactivate the bacterial cell. Growth curve analysis also showed a longer lag and a shorter log phase in the presence of nanocomposites, indicating effective antimicrobial activity.

中文翻译：

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使用纳米复合材料抑制从废水处理设施中分离出的多种耐药细菌、斯堪的纳维亚哥德堡 CCUG 66741 和维罗尼气单胞菌 CRC6

摘要

抗生素耐药性目前是全球健康和社会经济发展面临的最严峻挑战之一。新的耐药机制正在世界范围内出现和传播，对我们治疗常见传染病的能力构成威胁。抗生素主要通过废水处理厂释放到环境中。抗生素的存在可能有利于抗生素抗性基因 (ARG) 和抗生素抗性细菌 (ARB) 的选择。ARBs 是从处理过的城市废水样品中分离出来的。对形态不同、数量较多的耐药菌进行多重耐药检测。发现两个菌落对抗生素、氨苄青霉素、红霉素、利福平和氯霉素具有抗性。这些细菌菌落被鉴定为Scandinavium goeteborgense CCUG 66741 和Aeromonas veronii CRC6 使用 16S rRNA 基因测序。这些细菌也被发现是多重抗生素耐药性 (MAR) 指数为 0.6 的高风险污染源。它们不仅具有多重耐药性，而且是人类和动物病原体。此外，使用琼脂井扩散法评估了 500 mg/L纳米复合材料（Ag ⁰ NP@GO 和 Ag ^{0 NP@rGO）的抑制作用。两种细菌都被纳米复合材料抑制，显示出明显的透明区，Ag 0}引起的抑制作用更大NP@rGO。总体而言，合成的纳米复合材料的抗菌作用可以解释为“诱杀”机制。特别是，具有二维结构和表面官能团和电荷的 GO 纳米片有助于像捕获剂一样结合细菌细胞，而嵌入 GO 片中的银纳米颗粒使细菌细胞失活。生长曲线分析还显示在纳米复合材料存在下较长的滞后和较短的对数阶段，表明有效的抗微生物活性。