Conventional and Real-Time PCR Targeting blaOXA Genes as Reliable Methods for a Rapid Detection of Carbapenem-Resistant Acinetobacter baumannii Clinical Strains

Abstract

Multidrug-resistant Acinetobacter baumannii, particularly those producing carbapenemases, are spread worldwide. A reliable detection of carbapenemases is essential to choose the appropriate antimicrobial therapy and, consequently, prevent the dissemination of carbapenem-resistant strains. The aim of this study is to examine the molecular basis of the carbapenem resistance mechanism and estimation of conventional PCR and real-time PCR usefulness for the detection of oxacillinases when compared to phenotypic carbapenemases detection. The following methods were evaluated: the CarbAcineto NP test, Carbapenem Inactivation Method, CPO panels of semiautomated antimicrobial susceptibility testing method on the BD Phoenix™ M50 system, conventional Polymerase Chain Reaction and real-time PCR. The eazyplex® SuperBug complete A assay was used as the reference method. Among the tested strains, 39 (67.2%) carried the blaOXA-40 gene, while the blaOXA-23 gene was noted amongst 19 (32.8%) isolates. The diagnostic sensitivities of the studied assays were as follows: CarbAcineto NP—65.5%; CIM—100%; CPO—100%; conventional PCR—100%; real-time PCR—100%.