Identification of Class A, B and D Carbapenemases by Phenotypic and Molecular methods in organisms of the family Enterobacteriaceae

Dr. Sanjeev Kumar; Dr. S.K. Mehra

Volume : VII, Issue : VI, June - 2017

Identification of Class A, B and D Carbapenemases by Phenotypic and Molecular methods in organisms of the family Enterobacteriaceae

Dr. Sanjeev Kumar, Dr. S. K. Mehra

Abstract :

Detection of carbapenemases in particular members of the Enterobacteriaceae, is of utmost importance for the management of infected or colonized patients. Antimicrobial susceptibility was determined by disc diffusion method, results were interpreted according to CLSI guidelines. Phenotypic confirmation was done by modified Hodge test and Combined disc test. After phenotypic confirmation, 20 randomly selected isolates were further studied for the presence of carbapenem resistance (CRE) genes. By the molecular method (PCR), 17 isolates were positive for carbapenemase production and 3 isolates were showed non–specific PCR amplicons. All the 20 isolates were positive by combined disc method and only 8 isolates were positive by MHT. The sensitivity and specificity of the combined disc test was 100% and 66.67%, whereas modified Hodge test was 37.5% and 33.33% respectively, in comparison with the gold standard PCR method. Before performing such an expensive technique (PCR), we have to confirm by phenotypic methods.