Abstract: ［Abstract］ Objective〖HTSS〗〓To evaluate the screening capacity of carbapenem inactivation method (CIM) and modified carbapenem inactivation method (mCIM) for phenotypic carbapenemase activity in Enterobacteriaceae bacteria.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓A total of 110 isolates of carbapenemresistant Enterobacteriaceae and 25 isolates of carbapenemsensitive Enterobacteriaceae were selected, and carbapenemase activity were determined by the CIM and mCIM, respectively. Meanwhile，the carbapenemase genes such as KPC2, NDM1, IMP4,VIM1 and OXA48 were detected by PCR. The examination results were analyzed statistically.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓Of the 110 carbapenemresistant Enterobacteriaceae strains，99 strains were positive detected by PCR, including 77 strains for KPC2, 15 strains for NDM1, 2 strains for both KPC2 and NDM1, 4 strains for IMP4, and 1 strain for VIM1. The strain carring OXA48 gene was not detected. Twentyfive carbapenemsensitive strains were all negative. For CIM, the sensitivity is 87.9% and the specificity is 94.4%. For mCIM, the sensitivity is 95.0% and the specificity is 91.7%. In order to compare the effects of the diameter of bacteriostasis ring on the experimental results, the CIM negative strains were divided into two groups, carbapenemresistant gene positive group and carbapenemresistant gene negative group. The bacteriostasis diameter of the carbapenemresistant gene positive group was significantly lower than that of the gene negative group, and the difference was statistically significant（P＜001）.
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓After the optimization of the experimental procedure and the interpretation criteria of the results, the mCIM not only retained the advantages of low cost, simple operation, high sensitivity and good specificity, but the screening ability of carbapenemases had also been significantly improved. mCIM should be a convenient, costsaving and efficient phenotypic screening method.

Key words: Enterobacteriaceae, carbapenemase； genetic testing