Characterization of NDM-7 Carbapenemase-Producing Escherichia coli Isolates in the Arabian Peninsula.

Aim: The purpose of this study was to characterize the New Delhi metallo-beta lactamase (NDM)-7-producing Enterobacteriaceae isolated in the Arabian Peninsula.
Methods: Enterobacteriaceae identified to carry bla _NDM-7 in a collection of 157 NDM-producing isolates from Kuwait, Oman, Saudi Arabia, and the United Arab Emirates (UAE) were investigated for their antibiotic and disinfectant susceptibility, and resistance gene content. The virulence profile, phylogenetic and sequence types of the isolates were also determined. The plasmids carrying the bla _NDM-7 were transferred, and their complete nucleotide sequence was determined.
Results: Four NDM-7-producing Escherichia coli isolated in Kuwait, Oman, and the UAE, respectively, were identified. They were clonally unrelated, carried a few virulence determinants only, and belonged to clonal complexes CC10 and CC23, or ST448. They were all multi-drug resistant but remained susceptible to fosfomycin, tigecycline, and colistin. In all isolates, bla _NDM-7 was located on IncX3 type plasmids of a variable size, not harboring any further resistance genes. The plasmids exhibited a high degree of similarity to each other and to pKpN01-NDM7 from Canada, with various size deletions and insertions.
Conclusions: Our findings show that IncX3 type plasmids play an important role in the spread of the currently rare NDM-7 variant in the Arabian Peninsula. This association of bla _NDM-7 with the IncX3-type plasmid is particularly worrisome, as this type of plasmid was proved to spread other carbapenemases in various species of Enterobacteriaceae worldwide at a high efficiency.