Novel variant NDM-11 and other NDM-1 variants in multidrug-resistant Escherichia coli from South India

Mohibur Rahman, Chiranjay Mukhopadhyay, Ravi Prakash Rai, Sanjay Singh, Shefali Gupta, Avinash Singh, Ashutosh Pathak, Kashi Nath Prasad

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Objectives: Carbapenem resistance mediated by New Delhi metallo-β-lactamase 1 (NDM-1) and its variants has caused a major public-health concern worldwide. Here we report for the first time an Escherichia coli isolate positive for a novel variant (NDM-11). Methods: blaNDM genes were investigated in E. coli by PCR and sequencing, and blaNDM variants were further characterised. The susceptibility pattern of novel blaNDM-11 towards different antimicrobials was compared with blaNDM-1 by cloning and expression in E. coli TOP10. Results: A total of 33 carbapenem-resistant E. coli isolates were screened by PCR for the presence of blaNDM, of which 15 (45.5%) were positive. Sequencing of the PCR products revealed 10 isolates with NDM-1 and 5 isolates with NDM variants (one each of NDM-4, NDM-8 and NDM-11 and two NDM-5). Other resistance genes, including blaTEM-1, blaCTX-M-15, blaVIM, plasmid-encoded AmpC blaCMY-2 and 16S methyltransferases (rmtB and rmtC), were also associated with NDM variants in different combinations. The blaNDM variants were located on a transferable IncF-type plasmid of >100 kb. Pulsed-field gel electrophoresis (PFGE) showed that all five E. coli isolates were unrelated, and multilocus sequence typing (MLST) revealed that they all belonged to ST131. Expression of the blaNDM-1 and blaNDM-11 genes in E. coli TOP10 showed no significant difference in MICs to various β-lactams, including carbapenems. Conclusions: This study underlines the spread of NDM variants with other antimicrobial resistance genes in E. coli in South India. It also describes a novel NDM variant (blaNDM-11) having an antimicrobial resistance pattern similar to blaNDM-1.

Original languageEnglish
Pages (from-to)154-157
Number of pages4
JournalJournal of Global Antimicrobial Resistance
Publication statusPublished - 01-09-2018

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Immunology and Allergy
  • Immunology
  • Microbiology (medical)


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