Reliability of carbapenem inactivation method (CIM) and modified carbapenem inactivation method (mCIM) for detection of OXA-48-like and NDM-1

Meher Rizvi*, Hiba Sami, Mohammad Azam, Dhoha Ben Khalid, Zaaima AL Jabri, Fatima Khan, Asfia Sultan, Anuradha Singh, Nusrat Perween, Munawer AL Quraini, Zakariya AL Muharrmi, Syed G. Rizvi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Purpose: Carbapenem inactivation method (CIM) and modified carbapenem inactivation method (mCIM) were recently developed for rapid detection of carbapenemase producing Gram negative bacilli (CP-GNB). In this study we compared the ability of modified Hodge test (MHT), CIM and mCIM to identify CP-GNB in Oman and India. Methods: Fifty fully characterized and genotyped CP-GNB (26 OXA-48-like, 2 NDM-1 from Oman and 22 NDM-1 from India) and 8 AmpC as controls in India were subjected to MHT, CIM, mCIM and mCIM with in-house modifications. Wilcoxon paired test and receiver operating characteristics (ROC) were utilised for statistical analysis. Results: Isolates were predominantly OXA-48-like genes producing Klebsiella pneumoniae from Oman and NDM-1 producing Escherichia coli from India. MHT was positive in all except one OXA-48-like producers and in 70.8 ​% of the NDM-1 isolates. The sensitivity of CIM in detecting 0XA-48 like and NDM-1 carbapenemases were 39.2% and 87.5% respectively. mCIM at 4 ​h detected 92.3 ​% and 79.1% of 0XA-48 and NDM-1 respectively. Using receiver operative characteristics (ROC), highest sensitivity and specificity for detection of OXA-48-like was obtained by mCIM at 4 ​h at cut off 17 ​mm while for NDM-1 CIM was the test of choice at 16 ​mm. Conclusion: CIM and mCIM are simple, cheap and easy tests to perform. CIM gave excellent results with NDM1 strains while it was quite poor in predicting OXA-48-like. We recommend CIM and eCIM for rapid identification of NDM-1 producers and mCIM at 4 ​h and MHT for detection of OXA-48-like. No one method can correctly detect both genotypes. As determined by ROC curves a zone of inhibition of 17 ​mm was considered adequate for detection of OXA-48-like and 16 ​mm of NDM-1 by mCIM at 4 ​h and CIM respectively.

Original languageEnglish
Pages (from-to)451-456
Number of pages6
JournalIndian Journal of Medical Microbiology
Issue number4
Publication statusPublished - Oct 1 2021


  • Carbapenem inactivation method (CIM)
  • Carbapenemases
  • Modified hodge test
  • NDM1
  • mCIM

ASJC Scopus subject areas

  • Immunology and Microbiology (miscellaneous)
  • Microbiology (medical)
  • Infectious Diseases
  • Immunology and Microbiology(all)
  • Immunology and Allergy
  • Microbiology
  • Immunology


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