Molecular characterization of NDM-1 producing Enterobacteriaceae isolates in Singapore hospitals

Authors

  • Jeanette Teo Department of Laboratory Medicine, National University Hospital, Singapore, 119074 Singapore.
  • Grace Ngan
  • Michelle Balm
  • Roland Jureen
  • Prabha Krishnan
  • Raymond Lin

DOI:

https://doi.org/10.5365/wpsar.2011.2.4.010

Abstract

Objective: In this study, we molecularly characterized 12 NDM-1 producing clinical Enterobacteriaceae (Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae) isolates that were part of a collection of non-carbapenem susceptible isolates obtained during a one-year period. These isolates were obtained from four local general hospitals in Singapore.

Methods: Polymerase chain reaction (PCR) assays and sequencing was used to determine the presence of ?-lactamase encoding genes (bla) including blaNDM-1 and plasmid-mediated quinolone and aminoglycoside resistance determinants. Conjugation experiments were performed to determine the transferability of blaNDM-1. Isolate relatedness was determined by multilocus sequence typing (MLST).

Results: The isolates were completely resistant to the second- and third-generation cephalosporins tested as well as carbapenems. Susceptibility profiling of the isolates indicated that 100% retained susceptibility to tigecycline while 11/12 (91.7%) were susceptible to colistin. The blaNDM-1 gene was encoded on plasmids that were easily transferable. None of the patients had a travel history to countries where NDM-1 has been reported. The isolates appear clonally unrelated with MLST, revealing a diversity of clonal types among the Klebsiella pneumoniae and Escherichia coli isolates.

Conclusion: The ease of NDM-1 plasmid transmissibility may help their dissemination among the Enterobacteriaceae. Although it appears that the isolates are clonally unrelated, epidemiological links cannot be fully excluded without further research.

How to Cite

1.
Teo J, Ngan G, Balm M, Jureen R, Krishnan P, Lin R. Molecular characterization of NDM-1 producing Enterobacteriaceae isolates in Singapore hospitals. Western Pac Surveill Response J [Internet]. 2013 May 30 [cited 2024 Nov. 23];3(1). Available from: https://ojs.wpro.who.int/ojs/index.php/wpsar/article/view/137

Issue

Section

- Original Research

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