Molecular epidemiology and genomic characterization of a plasmid-mediated and co-harboring multidrug-resistant .

Colistin is considered as one of the last-resort antimicrobial agents for treating multidrug-resistant bacterial infections. Multidrug-resistant has been increasingly isolated from clinical patients, which posed a great challenge for antibacterial treatment. This study aimed to report a and co-carrying clinical isolate 5549 conferred a high-level resistance against colistin. Antibiotic susceptibility testing was performed using the microdilution broth method. Transferability of and -carrying plasmids were investigated by conjugation experiments. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to identify modifications in lipid A. Whole genome sequencing and phylogenetic analysis between strain 5549 and a total of 301 genomes retrieved from NCBI database were performed. The genetic characteristics of and -bearing plasmids were also analyzed. Our study indicated that strain 5549 showed extensively antibiotic-resistant trait, including colistin and carbapenem resistance. The and were carried by IncFIB/IncFII type p5549_mcr-10 (159417 bp) and IncN type p5549_NDM-1 (63489 bp), respectively. Conjugation assays identified that only the -carrying plasmid could be successfully transferred to J53. Interestingly, did not mediate colistin resistance when it was cloned into DH5α. Mass spectrometry analysis showed the lipid A palmitoylation of the C-lacyl-oxo-acyl chain to the chemical structure of lipid A at 2063 in strain 5549. In summary, this study is the first to report a and co-occurrence recovered from China. Our investigation revealed the distribution of different clonal lineage of with epidemiology perspective and the underlying mechanisms of colistin resistance. Active surveillance is necessary to control the further dissemination of multidrug-resistant .