2020 年 73 巻 2 号 p. 45-53
The MASTDISCS combi Carba plus is a set of inhibitor combination discs that differentiates carbapenemases from AmpC β-lactamases. We evaluated the performance of this disc set in discriminating β-lactamase genotypes using 36 clinical and 5 reference strains, as well as discriminating clinical isolates using phenotypic assays. The results for all Enterobacteriaceae strains producing 21 carbapenemases (16 clinical isolates and 5 reference strains), including 14 IMP-1, 1 VIM-1, 2 NDM, 2 OXA-48, and 2 KPC carbapenemases, using the MASTDISCS combi Carba plus were consistent with the genotypes identified by multiplex PCR. Sixteen carbapenemase-producing Enterobacteriaceae clinical isolates were positive for carbapenemase production according to the modified carbapenem inactivation methodology, and 13 MBL-producing strains were positive for carbapenemase production according to the sodium mercaptoacetic acid double disc synergy test. Twenty-one of the AmpC β-lactamase- and ESBL-producing strains were identified as AmpC- or non-carbapenemase-producing Enterobacteriaceae using the MASTDISCS combi Carba plus. Ten AmpC β-lactamase-producing clinical strains were all positive for the aminophenyl boronic acid double disc synergy test. Overall, the MASTDISCS combi Carba plus allowed easy identification and successful typing of major carbapenemases using routine microbiology methods.
