Common isolation of New Delhi metallo-beta-lactamase 1-producing Enterobacteriaceae in a large surgical hospital in Vietnam

Abstract

This study sought to monitor the presence of carbapenem-resistant Enterobacteriaceae (CRE) and the proportion New Delhi metallo-beta-lactamase 1 (NDM-1)-producing bacteria between August 2010 and December 2012 in a surgical hospital in Vietnam. We identified 47 CRE strains from a total of 4,096 Enterobacteriaceae isolates (1.1 %) that were NDM-1-positive from 45 patients admitted to 11 different departments, with the majority being from the urology department. The NDM-1 gene was found in seven different species. Genotyping revealed limited clonality of NDM-1-positive isolates. Most of the isolates carried the NDM-1 gene on a plasmid and 17.8 % (8/45) of those were readily transferable. We found five patients at admission and one patient at discharge with NDM-1-positive bacteria in their stool. From 200 screening environmental hospital samples, five were confirmed to be NDM-1-positive and included Acinetobacter species (n = 3) and Enterobacter aerogenes (n = 2). The results reveal that NDM-1-producing Enterobacteriaceae are commonly isolated in patients admitted to a Vietnamese surgical hospital and are also detected in the hospital environment.

Fig. 1

Proportion of NDM-1 among phenotypic of carbapenem-resistant bacteria

Fig. 2

Distribution of NDM-1-positive cases by month and department (n = 45)

Fig. 3

a The differences in plasmid number from a selection of bacteria isolates. Several isolates contained up to eight plasmids b S1-PFGE and Southern blotting of plasmids carrying NDM-1 from clinical isolates. Pulsed-field gel of S1-treated plasmid DNA of selected Enterobacteriaceae from clinical isolates stained with ethidium bromide. The molecular weight marker is S. braenderup H9812 cut with XbaI (A). Autodiagram of gel A showing plasmids carrying NDM-1 (B)