Occurrence of <em>mcr</em> Positive Strains and Molecular Characteristics of Two <em>mcr-1</em> Positive <em>Salmonella typhimurium</em> and <em>Escherichia coli</em> from a Chinese Women’s and Children’s Hospital

Infect Drug Resist. 2021 Jul 27;14:2925-2932. doi: 10.2147/IDR.S322686. eCollection 2021.


BACKGROUND: The purpose of this study was to evaluate the prevalence of mobile colistin resistance genes (mcr) in Gram-negative bacteria and to analyze the molecular characteristics of mcr-1 positive Salmonella typhimurium strain 75 and Escherichia coli strain 107 from the Quanzhou Women's and Children's Hospital in China.

METHODS: The genes mcr-1 through mcr-9 were screened via multiplex PCR. Antibiotic susceptibility was detected using a GN11 card with the VITEK-2 compact automated system. Whole genomes were sequenced using PacBio's single molecule real-time (SMRT) technology.

RESULTS: In this study, mcr-1 was detected in only four strains, with a positivity rate of 0.65% (4/616). All the four strains were resistant to more than three different kinds of antibiotics. The mcr-1 positive S. typhimurium strain 75 harbored IncHI2 plasmid, which carried mcr-1 gene, while the mcr-1 positive E. coli strain 107 contained four plasmids including one mcr-1 harboring IncHI2 plasmid, one IncFII plasmid and two IncI1-I (Alpha) plasmids. Mobile elements carrying mcr-1 in the 75_plasmid and 107_plasmid-1 were located in the IS1086(ISApl1)-IS30A(ISApl1)-mcr-1-hp and IS1086(ISApl1)-mcr-1-hp regions, respectively. Tn6010 carrying drug efflux pump genes was found in 75_plasmid, while cn_31611_IS26 carrying multi-drug resistance (MDR) genes were found in 107_plasmid-1.

CONCLUSION: This study found that mcr-1 was prevalent at a low frequency in the Quanzhou Women's and Children's Hospital. A similar genetic pattern of mcr-1 transmission was found in both E. coli and S. typhimurium.

PMID:34349527 | PMC:PMC8327187 | DOI:10.2147/IDR.S322686