College of Veterinary Medicine, Yangzhou Universitygrid.268415.c, Yangzhou, China.
Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
Microbiol Spectr. 2022 Apr 27;10(2):e0216021. doi: 10.1128/spectrum.02160-21. Epub 2022 Mar 1.
Horizontal gene transfer (HGT) plays a significant role in the spread of antibiotic resistance genes (ARGs). Most reported compounds promote HGT by increasing the cell membrane permeability. Colistin has been reported to increase the cell membrane permeability when exhibiting its antibacterial effect. Therefore, this study aimed to investigate the potential role of colistin in facilitating the dissemination of ARGs via plasmid conjugation by establishing an mating model. Three strains Escherichia coli (E. coli) DH5α, E. coli L65, and E. coli LD67-1 carrying plasmid RP4-7, positive IncX3 plasmid, and positive IncI2 plasmid, respectively, were regarded as the donor strains and E. coli J53 as the recipient strain. Exposure to subinhibitory concentrations of colistin (1/4, 1/8, 1/16 MIC) significantly stimulated the conjugation frequency of RP-4 plasmid, wide-type IncI2 and IncX3 plasmid. Scanning electron microscopy revealed the shrunken cell membrane after colistin treatment, whereas propidium iodide dye and 1--Phenylnaphthylamine fluorescent probe showed the increased cell membrane permeability. Additionally, the expression level of the outer membrane proteins ( and ) was increased. These results indicate a break in the membrane barrier. The expression of the mating pair formation gene () was promoted and the expression of the global regulatory genes (, ), which downregulates expression, was inhibited. Thus, the production of the mating pairing machine could be elevated after colistin exposure. These findings aid in understanding the hidden risks of colistin on the spread of antimicrobial resistance. Antimicrobial resistance (AMR) dissemination is a growing global threat. As a last-resort treatment against multidrug-resistant and extensively drug-resistant Gram-negative bacteria, colistin has been used for prophylactic and therapeutic purposes in veterinary medicine. Previous studies have reported the presence of colistin residues in the intestinal tract and feces. The role of colistin in facilitating the conjugation frequency of and -positive plasmids was confirmed in this study along with elucidating its potential mechanisms. This study raises awareness of the potential AMR dissemination roles induced by colistin in environmental settings.
水平基因转移（HGT）在抗生素耐药基因（ARGs）的传播中起着重要作用。大多数报道的化合物通过增加细胞膜通透性来促进 HGT。多粘菌素在发挥其抗菌作用时已被报道会增加细胞膜通透性。因此，本研究旨在通过建立接合模型，研究多粘菌素通过增加质粒接合促进 ARG 传播的潜在作用。三株大肠杆菌（E. coli）DH5α、E. coli L65 和 E. coli LD67-1 分别携带质粒 RP4-7、阳性 IncX3 质粒和阳性 IncI2 质粒，被视为供体菌株，大肠杆菌 J53 被视为受体菌株。亚抑菌浓度的多粘菌素（1/4、1/8、1/16 MIC）显著刺激了 RP-4 质粒、广谱 IncI2 和 IncX3 质粒的接合频率。扫描电子显微镜显示多粘菌素处理后细胞膜皱缩，而碘化丙啶染料和 1--萘基苯并噻唑荧光探针显示细胞膜通透性增加。此外，外膜蛋白（ 和 ）的表达水平增加。这些结果表明膜屏障被打破。配对形成基因（）的表达促进，全局调节基因（，）的表达受到抑制，该基因下调 表达。因此，多粘菌素暴露后，配对机器的产生可能会增加。这些发现有助于理解多粘菌素对抗菌药物耐药性传播的隐藏风险。抗生素耐药性（AMR）传播是一个日益严重的全球威胁。多粘菌素作为治疗多重耐药和广泛耐药革兰氏阴性菌的最后手段，已在兽医学中用于预防和治疗。以前的研究报告称，肠道和粪便中存在多粘菌素残留。本研究证实了多粘菌素在促进 和 -阳性质粒的接合频率方面的作用，并阐明了其潜在机制。本研究提高了人们对多粘菌素在环境中诱导抗生素耐药性传播的潜在作用的认识。
