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

We characterized the first NDM-5 and MCR-8.2 co-harboring ST656 clinical isolate, combining with chromosomal gene-mediated resistance to colistin and tigecycline. The 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 -carrying plasmids. The KP32558 was identified as a pan-drug resistant bacteria, belonging to ST656, and harbored plasmid-encoded and genes. The gene was located on an IncX3 type plasmid. The gene was located on a conjugative plasmid pKP32558-2-mcr8, which had a common ancestor with another two -carrying plasmids pMCR8_020135 and pMCR8_095845. The MIC of KP32558 for colistin was 256 mg/L. The gene and mutations in the two-component system, and , and the regulator , had a synergistic effect on the high-level colistin resistance. The truncation in the gene, related to tigecycline resistance, was also identified. 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.