High diversity of bla(NDM-1)-encoding plasmids in Klebsiella pneumoniae isolated from neonates in a Vietnamese hospital

Objectives: The carbapenemase-encoding gene bla(NDM-1) has been reported in Vietnam during the last 10 years, and bla(NDM)-producing Enterobacteriaceae are now silently and rapidly spreading. A key factor behind dissemination of bla NDM-1 is plasmids, mobile genetic elements that commonly carry antibiotic resistance genes and spread via conjugation. The diversity of bla(NDM-1)-encoding plasmids from neonates at a large Vietnamese hospital was characterized in this study.Methods: 18 fecal Klebsiella pneumoniae and Klebsiella quasipneumoniae isolates collected from 16 neonates at a large pediatric hospital in Vietnam were studied using optical DNA mapping (ODM) and next-generation sequencing (NGS). Plasmids carrying the bla(NDM-1) gene were identified by combining ODM with Cas9 restriction. The plasmids in the isolates were compared to investigate whether the same plasmid was present in different patients.Results: Although the same plasmid was found in some isolates, ODM confirmed that there were at least 10 different plasmids encoding bla(NDM-1) among the 18 isolates, thus indicating wide plasmid diversity. The ODM results concur with the NGS data. Interestingly, some isolates had two distinct plasmids encoding bla(NDM-1) that could be readily identified with ODM. The coexistence of different plasmids carrying the same bla(NDM-)1 gene in a single isolate has rarely been reported, probably because of limitations in plasmid characterization techniques.Conclusions: The plasmids encoding the bla(NDM-1) gene in this study cohort were diverse and may represent a similar picture in Vietnamese society. The study highlights important aspects of the usefulness of ODM for plasmid analysis. (c) 2021 The Author(s). Published by Elsevier Ltd.