Discussion on the Problems of Vitek 2 Compact Advanced Expert System to Identify Carbapenemase Phenotypes in Isolates of Enterobacteriaceae / 现代检验医学杂志

ABSTRACT

Objective To explore the accuracy of Vitek 2 compact advanced expert system (AES) in indicating and analyze the carbapenemases-resisting Enterobacteriaceae phenotypes,and further investigate the methods to make up the AES.Methods 28 Enterobacteriaceae strains with Imipenem-Nonsusceptible by Vitek 2 compact,but AES suggested all production of carbapenemases were isolated.And imipenem susceptibility was determined by the disk diffusion method.Modified Hodge test (MHT) and the metallo-β-1actamase was detected by the double disk synergy method.Resistance genes were detected by the PCR amplification.Results ESBLs gene was amplified from all 28 selected strains,16 of which was detected KPC gene,and no strain of metallo-β-1actamases-producing bacteria.With carbapenemase gene detection as the gold standard,the accuracy of AES was 57.1％.Disc diffusion method detection accuracy rate of imipenem was 100％,and for 100％ of MHT accuracy.PCR amplification,MHT and the disk diffusion displayed the same result in detecting carbapenemases,but different with AES (x2 =10.08,P＜0.05).Conclusion The indications of the presence of carbapenemases using AES was not completely correct with a certain false-positive,and it is necessary to take other methods,such as disk diffusion or MHT methods,and improve the reliability of medicine-sensitivity tests.