Phenotypic and molecular detection of carbapenemase producing Escherichia coli and Klebsiella pneumoniae

Abstract

Background:Detection of carbapenemases properly and rapidly is vital in the fight against the emergence and spread of carbapenem resistant bacteria. This study was carried out to phenotypically and molecularly detect carbapenemase producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae ). Methods: A total of 123 isolates consisting 70isolates of E. coli and 53 isolates of K. pneumoniae were screened for carbapenem resistant isolates (CRIs). The CRIs were then screened phenotypically for carbapenemase production using the Modified Hodge Test (MHT), Carba NP test and modified Carbapenem Inactivation Method (mCIM). The CRIs were also screened molecularly for carbapenemase genes by PCR and the carbapenemase genes detected were sequenced. Results: Out of the 123 isolates screened for carbapenem resistance, 6 (4.88%) comprising of 2 isolates of E. coli (2/70; 2.86%) and 4 isolates of K. pneumoniae (4/53; 7.55%) were carbapenem resistant isolates. Phenotypically, all the 6 CRIs (100.00%) were positive for carbapenemase by mCIM. However, 5 (83.33%) were positive by CarbaNP and 4 (66.66%) were positive by MHT. Carbapenemase genes were detected in five out of the six carbapenem resistant isolates screened. The most frequently detected carbapenemase gene was blaOXA gene (57.14%) followed by blaNDM gene (42.86). blaKPC gene was not detected (0.00%). The detection rates of OXA and NDM carbapenemases were found be to 100.0% by Carba NP test and mCIM while the rates of OXA and NDM carbapenemases by MHT were found to be 75.0% and 33.33% respectively. Conclusion: Carbapenemase producing K. pneumoniae and E. coli were detected both phenotypically and molecularly. The carbapenem resistant determinants were blaOXA and blaNDM gene.

Keywords

• phenotypic
• carbapenemase
• k. pneumoniae
• e. coli
• resistance molecular