The inhibitor enhanced carbapenem inactivation method for the detection of metallo-p-lactamases and class A KPC carbapenemases in Enterobacteriaceae

ObjectiveEvaluation of inhibitor enhanced carbapenem inactivation method detection of metallo-para-lactamases and class A KPC carbapenemases in clinical isolates of carbapenemase-resistant Enterobacteriaceae (CRE).

MethodsTwo hundred and twenty seven clinical strains of CRE clinical samples were collected from Lu'an People's Hospital from 2020 to 2021.The type of carbapenemase was detected by the disk diffusion test for Imipenem (IPN) combined with 2 different inhibitors(phenylboronic acid and EDTA).The PCR amplification of drug-resistant genes was set as the gold standard to evaluate the simple phenotypic method.

ResultsTwo hundred and twenty-seven CRE strains were amplified by PCR, in which 218 strains were confirmed to produce carbapenemase, including 164 strains producing KPC, 53 strains producing metallo-β-lactamases.The sensitivity and specificity of the KPC phenotype detected by IPN combined with phenylboronic acid synergy test were 100.0% and 95.2%, respectively.The sensitivity and specificity of the IPN combined with the EDTA synergy test to detect MBL phenotype were both 100.0%.

ConclusionsThe simple phenotypic method has the high sensitivity and specificity for the detection of KPC and MBL carbapenemase, which is easy to operate and interpret, which is worth to be popularized and applied in various experiments.