Co-existence of plasmid-mediated bla NDM-1 and bla NDM-5 in Escherichia coli sequence type 167 and ST101 and their discrimination through restriction digestion

Abstract

The global dissemination of antimicrobial resistance genes is a serious concern. One such gene, bla NDM , has spread globally via plasmids. bla NDM confers resistance against all β-lactam antibiotics, except monobactams. Most of the earlier literature reported the presence of single bla NDM variant. However, this study reports the prevalence of dual bla NDM variants ( bla NDM-1 and bla NDM-5 ) located on two separate plasmids identified in two distinct Escherichia coli epidemic clones ST167 and ST101 isolated from a septicemic neonate and a pregnant mother, respectively. bla NDM-5 differs from bla NDM-1 due to the presence of two point mutations (i.e., V88L and M154L). This study detected dual bla NDM variants through Sanger sequences and further validated them through hybrid-genome assembly. Detection of multiple bla NDM variants in a single isolate remains difficult until genome sequencing or southern blotting is carried out. Hence, a simple restriction digestion method was devised to rapidly screen dual bla NDM variants containing M154L mutation.