High diversity of blaNDM-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.

Automated summary

The diversity of bla(NDM-1)-encoding plasmids from neonates at a large Vietnamese hospital was characterized using optical DNA mapping (ODM) and next-generation sequencing (NGS). The results showed that there were at least 10 different plasmids encoding bla(NDM-1) among the 18 isolates, indicating wide plasmid diversity. This study highlights the importance of ODM for plasmid analysis.