title: Comparison of phenotypic and PCR methods for detection of carbapenemases production by Enterobacteriaceae.
abstract: Dissemination of carbapenem resistance via Enterobacteriaceae, particularly amongKlebsiella pneumoniaeandEscherichia coli, is a major public health concern. Rapid methods for determining antimicrobial susceptibility are important to ensure adequate and appropriate use of antimicrobial agents and to limit the spread of these bacteria. In the current study, we compared the rapidity, sensitivity and specificity of traditional methods and molecular-based Xpert Carba-R PCR assay to identify sixty isolates, (26E. coliand 34K. pneumoniae). The specificity of MicroScan was 100% while sensitivity to ertapenem (ERT), imipenem (IMI), and meropenem (MER) was 93%, 68.9%, and 55.17%, respectively. For the modified Hodge test, the specificity was 96.77% and sensitivity was 89.65%. Although some results of phenotypic assays matched with the definite PCR identification, some results were misleading. Out of the 29 positive PCR samples, three samples ofK. pneumoniaewere negative for the MHT and oneE. colisample was MHT positive but negative for the PCR. Nine samples were positive for the PCR but were determined as carbapenem sensitive by MicroScan. While MicroScan and MHT requires several hours and multi-steps to obtain results, Xpert Carba-R PCR assay takes less than an hour. Therefore, we recommend using Gene xpert Carba-R assay for the optimal carbapenemnase detection with reducing material, manpower and cost. Also it is important to know the type of carbapenemase is present.
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Saudi Arabia.
authors.forename: Maryam
authors.initials: M
authors.lastname: AlTamimi
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Saudi Arabia.
authors.forename: Ali
authors.initials: A
authors.lastname: AlSalamah
authors.affiliation: Department of Botany and Microbiology, College of Science, King Saud University, Saudi Arabia.
authors.forename: Manal
authors.initials: M
authors.lastname: AlKhulaifi
authors.affiliation: Prince Sultan Military Medical City, Saudi Arabia.
authors.forename: Hisham
authors.initials: H
authors.lastname: AlAjlan
keywords: Antibiotic resistance; Carbapenemase; E. coli; Gene Xpert Carba-R assay; Klebsiella pneumonia; MicroScan; Modified Hodge test; PCR; Phenotypic