Increasing prevalence and dissemination of NDM-1 metallo-β-lactamase in India: data from the SMART study (2009)

J Antimicrob Chemother. 2011 Sep;66(9):1992-7. doi: 10.1093/jac/dkr240. Epub 2011 Jun 14.


Objectives: To investigate the β-lactamase background of ertapenem non-susceptible isolates for the presence of the most commonly detected carbapenemase genes, bla(KPC), bla(OXA-48) and bla(VIM), and the newly described bla(NDM-1).

Methods: Two hundred and thirty-five ertapenem-non-susceptible (MIC ≥ 0.5 mg/L) isolates of Enterobacteriaceae from the worldwide Study for Monitoring Antimicrobial Resistance Trends (SMART) 2009 programme were screened using a multiplex PCR for the presence of bla(KPC), bla(OXA-48), bla(VIM) and bla(NDM-1) genes. Extended-spectrum β-lactamase (ESBL) and AmpC genes (bla(ESBL) and bla(AmpC)) were identified using the Check-MDR CT101 microarray. DNA sequencing was performed to identify the bla(ESBL), bla(KPC) and bla(NDM-1) genes. Molecular typing was also performed to genetically characterize these isolates.

Results: Sixty-six isolates (28%) had a carbapenemase gene, with bla(NDM-1) identified in 33 isolates including 2 isolates carrying both bla(NDM-1) and bla(OXA-48); other carbapenemase genes found included bla(KPC) (n = 23), bla(VIM) (n = 7) and bla(OXA-48) (n = 3). All bla(NDM-1)-carrying isolates were from patients in India and comprised five different species. With the exception of one isolate carrying only bla(NDM-1), all bla(NDM-1) carbapenemase-possessing isolates carried additional β-lactamases in various combinations: bla(ESBL) and bla(AmpC) (n = 18); bla(ESBL) (n = 10); bla(ESBL), bla(AmpC) and bla(OXA-48) (n = 2); and bla(AmpC) (n = 2). Except for bla(OXA-48)-carrying isolates, novel multilocus sequence types or enterobacterial repetitive intergenic consensus PCR patterns were observed along with clonal dissemination within and among sites.

Conclusions: A range of carbapenemase genes, associated with diverse ESBLs and/or AmpC backgrounds, were found among Enterobacteriaceae isolated during the study. Many of these ertapenem non-susceptible strains were clonally related and carried various combinations of β-lactamases.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Cluster Analysis
  • DNA, Bacterial / genetics
  • Drug Resistance, Bacterial / genetics
  • Enterobacteriaceae / enzymology
  • Enterobacteriaceae / genetics*
  • Enterobacteriaceae Infections / epidemiology*
  • Enterobacteriaceae Infections / microbiology
  • Environmental Monitoring
  • Epidemiological Monitoring
  • Genetic Variation
  • Humans
  • India / epidemiology
  • Microarray Analysis
  • Microbial Sensitivity Tests
  • Multilocus Sequence Typing
  • beta-Lactamases / genetics*
  • beta-Lactams / pharmacology


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • beta-Lactams
  • beta-Lactamases
  • beta-lactamase NDM-1