1,344
Views
97
CrossRef citations to date
0
Altmetric
Original Articles

Identification and characterization of a novel incompatibility group X3 plasmid carrying blaNDM-1 in Enterobacteriaceae isolates with epidemiological links to multiple geographical areas in China

, , , , , , , , & show all
Pages 1-6 | Received 30 Jul 2012, Accepted 26 Sep 2012, Published online: 25 Jan 2019
 

Abstract

The New Delhi metallo-β-lactamase (NDM-1) is one of the most important resistance traits in Enterobacteriaceae. We characterized nine blaNDM-1 producing Enterobacteriaceae recovered from seven patients who have recently travelled or been treated in India (n=1) or mainland China (n=6) during December 2010–May 2012. All the China-linked patients had no links to the Indian subcontinent. The blaNDM-1 carrying plasmids belonged to the novel IncX3 (∼50 kb, in seven isolates including two Escherichia coli, two Klebsiella pneumoniae, one Citrobacter freundii, one Enterobacter aerogenes and one E. cloacae), IncA/C2 (∼140 kb, in one E. coli) or FII-F1B groups (∼110 kb, in one E. coli). Restriction fragment length polymorphism analysis of the seven IncX3 plasmids revealed identical pattern in six and two bands difference in the remaining one. The IncX3 plasmids carrying blaNDM-1 were epidemiologically linked to Guangzhou (n=1), Hunan (n=4), Haifeng (n=1) and Dongguan (n=1) in mainland China. Complete sequencing of the IncX3 plasmid pNDM-HN380 revealed that it was 54 035 bp long and encoded 52 open reading frames. The blaNDM-1 gene was found in a transposon-like structure flanked by ISAba125 and IS26, inserted into the plasmid genetic load region. The sequences of the blaNDM-1 containing module within the two IS elements were identical to those previously described for blaNDM-1-positive Tn125 in the plasmids or chromosome of Acinetobacter isolates. In summary, this is the first description of IncX3 plasmids carrying blaNDM-1. The findings indicate the worrisome involvement of an epidemic plasmid in the dissemination of NDM-1 in China.

We thank Levina Lam, Ben Ho and Wilson Chan of the Centre for Genomic Sciences, University of Hong Kong for technical assistance. This work was supported by a commission grant (grant NO HK-09-01) from the Research Fund for the Control of Infectious Diseases (RFCID) of the Health and Food Bureau of the Hong Kong Special Administative Region Government. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.