Annals of Microbiology (Jun 2021)

Modified CIM test as a useful tool to detect carbapenemase activity among extensively drug-resistant Klebsiella pneumoniae, Escherichia coli and Acinetobacter baumannii

  • Abed Zahedi Bialvaei,
  • Alireza Dolatyar Dehkharghani,
  • Farhad Asgari,
  • Firouzeh Shamloo,
  • Parisa Eslami,
  • Mohammad Rahbar

DOI
https://doi.org/10.1186/s13213-021-01634-8
Journal volume & issue
Vol. 71, no. 1
pp. 1 – 10

Abstract

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Abstract Purpose Timely detection of carbapenemases is essential for developing strategies to control the spread of infections by carbapenem-resistant isolates. The purpose of this study was to determine the epidemiology of carbapenemase genes among carbapenem-resistant isolates of Acinetobacter baumannii, Klebsiella pneumoniae, and Escherichia coli. In addition, the efficacy of the modified Hodge test (MHT), Carba NP test, and modified carbapenem inactivation method (mCIM) were compared. Methods A total of 122 carbapenem-resistant clinical isolates including 77 K. pneumoniae, 39 A. baumannii, and six E. coli were collected from hospitalized patients. Three phenotypic methods, including the MHT, Carba NP test, and mCIM were used for investigation of carbapenemase production. In addition, polymerase chain reaction (PCR) was performed to detect carbapenemase-encoding genes. Result The sensitivity and specificity of the MHT were 75.0% and 100%, respectively. In addition, Carba NP displayed 80.8% sensitivity and 100% specificity, whereas the sensitivity and specificity were 90.4% and 100% for the mCIM test, respectively. Among carbapenem-resistant isolates, 70, 84, and 87 isolates exhibited positive results according to the MHT, Carba NP test, and mCIM, respectively. PCR indicated the presence of one or more carbapenemase genes in 119 of carbapenem-resistant isolates, with bla KPC and bla VIM being the most commonly encountered. Co-production of ‘KPC and OXA-48’, ‘KPC and VIM’, and ‘KPC and IMP’ was detected in three, nine, and seven isolates, respectively. Conclusion Our results confirm that the mCIM test is a useful tool for the reliable detection of carbapenemase activity in enterobacterial isolates, especially in clinical microbiological laboratories with limited resources.

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