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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
general
Copy Number Change of the NDM-1 Sequence in a Multidrug-Resistant Klebsiella pneumoniae Clinical Isolate
PLoS ONE, Volume 8, No. 4, Article e62774, Year 2013
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Description
The genetic features of the antimicrobial resistance of a multidrug resistant Klebsiella pneumoniae strain harboring blaNDM-1 were investigated to increase our understanding of the evolution of NDM-1. The strain, KPX, came from a Taiwanese patient with a hospitalization history in New Delhi. Complete DNA sequencing was performed; and the genes responsible for antimicrobial resistance were systematically examined and isolated by library screening. KPX harbored two resistance plasmids, pKPX-1 and pKPX-2, which are 250-kb and 141-kb in size, respectively, with blaNDM-1 present on pKPX-1. The plasmid pKPX-1 contained genes associated with the IncR and IncF groups, while pKPX-2 belonged to the IncF family. Each plasmid carried multiple antimicrobial resistance genetic determinants. The gene responsible for resistance to carbapenems was found on pKPX-1 and that for resistance to aztreonam was found on pKPX-2. To our surprise, we discovered that blaNDM-1 exists on pKPX-1 as multiple copies in the form of tandem repeats. Amplification of blaNDM-1 was found to occur by duplication of an 8.6-kb unit, with the copy number of the repeat varying from colony to colony. This repeat sequence is identical to that of the pNDM-MAR except for two base substitutions. The copy number of blaNDM-1 of colonies under different conditions was assessed by Southern blotting and quantitative PCR. The blaNDM-1 sequence was maintained in the presence of the antimicrobial selection; however, removal of antimicrobial selection led to the emergence of susceptible bacterial populations with a reduced copy number or even the complete loss of the blaNDM-1 sequence. The dynamic nature of the NDM-1 sequence provides a strong argument for judicious use of the broad-spectrum antimicrobials in order to reduce the development and spread of antimicrobial resistance among pathogens. © 2013 Huang et al.
Available Materials
https://efashare.b-cdn.net/share/pmc/articles/PMC3639163/bin/pone.0062774.s001.tif
https://efashare.b-cdn.net/share/pmc/articles/PMC3639163/bin/pone.0062774.s002.tif
https://efashare.b-cdn.net/share/pmc/articles/PMC3639163/bin/pone.0062774.s003.tif
Authors & Co-Authors
Kirby, Ralph
Taiwan, Taipei
National Yang-ming University Taiwan
Siu, Leung Kristopher
Taiwan, Zhunan
National Health Research Institutes Taiwan
Statistics
Citations: 74
Authors: 2
Affiliations: 4
Identifiers
Doi:
10.1371/journal.pone.0062774
ISSN:
19326203
Research Areas
Genetics And Genomics
Health System And Policy
Study Approach
Quantitative