Cao Xingwei, Zhong Qiaoshi, Guo Yinjuan, Hang Yaping, Chen Yanhui, Fang Xueyao, Xiao Yanping, Zhu Hongying, Luo Hong, Yu Fangyou, Hu Longhua
Jiangxi Provincial Key Laboratory of Medicine, Clinical Laboratory of the Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, People's Republic of China.
Department of Clinical Laboratory Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200082, People's Republic of China.
Infect Drug Resist. 2021 Aug 28;14:3449-3458. doi: 10.2147/IDR.S311808. eCollection 2021.
Polymyxin resistance caused by the plasmid-mediated gene in gram-negative bacilli poses a huge threat to our health. In recent years, many regions have reported that and β-lactamase genes can coexist in a single strain.
In this study, 107 nonduplicate () isolates were collected from a tertiary hospital in Jiangxi, China. Antimicrobial susceptibility testing of isolates was performed using gram-negative susceptibility cards on the VITEK system. The minimum inhibitory concentrations (MICs) of polymyxin B was detected using the microdilution broth method. The presence of resistance genes was assessed using polymerase chain reaction (PCR). We subjected isolates to genotyping using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) and analyzed the transferability of plasmids with filter mating and electroporation. Subsequently, whole-genome sequencing was performed for plasmids.
Of the 107 isolates, 15 (14.0%) were resistant to polymyxin B. All polymyxin B-resistant isolates harbored at least one of the extended-spectrum β-lactamase genes tested. Only one isolate simultaneously harbored , and genes. MLST results showed that 15 carbapenem-resistant isolates belonged to five sequence types (STs). PFGE results displayed nine different PFGE clusters. Conjugation and transformation experiments and sequencing analysis showed that the strain had three plasmids, and , and were located on different plasmids.
The present study demonstrated for the first time the coexistence of , and in a ST485 isolate. The three plasmids carrying the , and genes can be transmitted in , which may lead to more severe bacterial resistance.
革兰氏阴性杆菌中由质粒介导的基因引起的多粘菌素耐药性对我们的健康构成了巨大威胁。近年来，许多地区报告称 和β-内酰胺酶基因可在单一菌株中共存。
在本研究中，从中国江西的一家三级医院收集了107株非重复的（）分离株。使用VITEK系统上的革兰氏阴性药敏卡对分离株进行药敏试验。采用微量肉汤稀释法检测多粘菌素B的最低抑菌浓度（MIC）。使用聚合酶链反应（PCR）评估耐药基因的存在情况。我们使用脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）对分离株进行基因分型，并通过滤膜接合和电穿孔分析质粒的可转移性。随后，对质粒进行全基因组测序。
在107株 分离株中，15株（14.0%）对多粘菌素B耐药。所有对多粘菌素B耐药的分离株均至少携带一种检测的超广谱β-内酰胺酶基因。仅一株分离株同时携带 、 和 基因。MLST结果显示，15株耐碳青霉烯类 分离株属于五种序列类型（STs）。PFGE结果显示有九个不同的PFGE簇。接合和转化实验及测序分析表明，该菌株有三个质粒， 、 和 位于不同质粒上。
本研究首次证明在一株ST485 分离株中 、 和 共存。携带 、 和 基因的三个质粒可在 中传播，这可能导致更严重的细菌耐药性。
