Analysis of clinical isolates of extended-spectrum β-lactamase-producing bacteria with primer and probe sets developed to detect blactx-m, blatem, and blashv using a fully automated gene detection system

Abstract

In this study, we evaluated extended-spectrum β-lactamase (ESBL)-producing bacteria with the newly developed primer and probe sets to detect blaCTX-M, blaTEM, and blaSHV using BD MAXTM, a fully automated multiplex polymerase chain reaction assay system. In 36 isolates confirmed by whole-genome sequencing to have blaCTX-M, blaTEM, or blaSHV, the developed primer and probe sets accurately detected each gene without being influenced by the presence of other β-lactamase genes. In nine control strains that do not harbor either blaCTX-M, blaTEM, or blaSHV no cross-reaction was observed. In 191 strains phenotypically determined to be ESBL-producers by conventional antimicrobial susceptibility tests, 189 strains were blaCTX-M-, blaTEM-, or blaSHV-positive as assessed by BD MAXTM using the developed primer and probe sets, and two strains were negative for these genes. Whole-genome sequencing revealed that these two strains were phenotypically false-positive ESBL-producers. The accuracy of the primer and probe sets seems to be satisfactory, and they may be applicable to detect CTX-M-type ESBL-producing bacteria.