Table_2_Convergence of MCR-8.2 and Chromosome-Mediated Resistance to Colistin and Tigecycline in an NDM-5-Producing ST656 Klebsiella pneumoniae Isolate From a Lung Transplant Patient in China.docx

We characterized the first NDM-5 and MCR-8.2 co-harboring ST656 Klebsiella pneumoniae clinical isolate, combining with chromosomal gene-mediated resistance to colistin and tigecycline. The K. pneumoniae KP32558 was isolated from the bronchoalveolar lavage fluid from a lung transplant patient. Complete genome sequences were obtained through Illumina HiSeq sequencing and nanopore sequencing. The acquired resistance genes and mutations in chromosome-encoded genes associated with colistin and tigecycline resistance were analyzed. Comparative genomic analysis was conducted between mcr-8.2-carrying plasmids. The K. pneumoniae KP32558 was identified as a pan-drug resistant bacteria, belonging to ST656, and harbored plasmid-encoded blaNDM-5 and mcr-8.2 genes. The blaNDM-5 gene was located on an IncX3 type plasmid. The mcr-8.2 gene was located on a conjugative plasmid pKP32558-2-mcr8, which had a common ancestor with another two mcr-8.2-carrying plasmids pMCR8_020135 and pMCR8_095845. The MIC of KP32558 for colistin was 256 mg/L. The mcr-8.2 gene and mutations in the two-component system, pmrA and crrB, and the regulator mgrB, had a synergistic effect on the high-level colistin resistance. The truncation in the acrR gene, related to tigecycline resistance, was also identified. K. pneumoniae has evolved a variety of complex resistance mechanisms to the last-resort antimicrobials, close surveillance is urgently needed to monitor the prevalence of this clone.

本研究对全球首例同时携带新德里金属β-内酰胺酶5（NDM-5）与可移动黏菌素耐药基因MCR-8.2（MCR-8.2）的ST656型肺炎克雷伯菌（Klebsiella pneumoniae）临床分离株进行了表征，该菌株同时携带染色体介导的黏菌素与替加环素耐药性。本研究分离得到的肺炎克雷伯菌KP32558，来源于一名肺移植患者的支气管肺泡灌洗液样本。通过Illumina HiSeq测序与纳米孔测序技术，获得了该菌株的完整基因组序列。研究团队对与黏菌素及替加环素耐药相关的获得性耐药基因及染色体编码基因突变进行了分析，并针对携带mcr-8.2的质粒开展了比较基因组学分析。经鉴定，肺炎克雷伯菌KP32558属于ST656型，为泛耐药菌株，其携带质粒编码的blaNDM-5与mcr-8.2耐药基因。blaNDM-5基因定位于IncX3型质粒上。mcr-8.2基因则位于接合性质粒pKP32558-2-mcr8，该质粒与另外两株携带mcr-8.2的质粒pMCR8_020135及pMCR8_095845具有共同的祖先。KP32558对黏菌素的最低抑菌浓度（Minimum Inhibitory Concentration, MIC）为256 mg/L。mcr-8.2基因与双组分系统pmrA、crrB及调控基因mgrB的突变，对该菌株的高水平黏菌素耐药性具有协同作用。研究同时鉴定出了与替加环素耐药相关的acrR基因截短突变。肺炎克雷伯菌针对这类终极抗菌药物已演化出多种复杂的耐药机制，因此亟需开展密切监测以监控该克隆株的流行态势。