Characterization of a cointegrate plasmid harbouring blaNDM-1 in a clinical Salmonella Lomita strain.

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Characterization of a cointegrate plasmid harbouring blaNDM-1 in a clinical Salmonella Lomita strain.

Int J Antimicrob Agents. 2019 Oct 07;:

Authors: Li R, Xie M, Liu L, Huang Y, Wu X, Wang Z, Chan EWC, Chen S

Abstract
This study aims to characterize molecular events underlying formation and evolution of a cointegrate plasmid harboring blaNDM-1 and blaCMY-2 in a clinical Salmonella Lomita strain. Salmonella strain SL131 was found to harbor two MDR plasmids. One plasmid, pSL131_IncHI2, is a typical IncHI2 plasmid containing blaOXA-1, catB3, arr-3, sul1, qnrB4 and blaDHA-1 in a complex class 1 integron. The other plasmid, pSL131_IncA/C-IncX3, is a blaNDM-1-bearing cointegrate plasmid consisting of the IncX3 and IncA/C backbones, formation of which is mediated by IS26. Stability assay showed that the cointegrate plasmid was highly stable in its natural host, S. Lomita, but would readily resolve into single plasmids upon conjugation, during which the IncX3 blaNDM-1-bearing plasmid could be transferred to E. coli strain EC600. Plasmid evolution through integration of two or more MDR plasmids together would not only expand the resistance profile of the resultant plasmid, but also broaden the host spectrum of such resistance-encoding mobile elements. Better understanding of the underlying and triggering mechanisms of cointegration may facilitate development of intervention measures to curb formation and dissemination of such elements.

PMID: 31600557 [PubMed - as supplied by publisher]