不同条件下CIM试验检测耐碳青霉烯类肠杆菌科细菌的评价

目的评估不同底物、不同孵育时间下碳青霉烯类抑制法(CIM)对肠杆菌科细菌碳青霉烯酶表型筛选能力的差异。方法分别用亚胺培南、美罗培南、厄他培南作为指示底物对120株耐碳青霉烯类肠杆菌科细菌(CRE)进行CIM试验,再以美罗培南为指示底物,分别孵育0.5、1、2、4h进行CIM试验,并采用PCR及测序技术检测菌株是否携带碳青霉烯酶相关基因。结果碳青霉烯酶耐药基因PCR检测结果显示,120株CRE中,阳性93株,阴性27株。以亚胺培南作为底物,阳性95株,阴性25株;以美罗培南作为底物,阳性87株,阴性33株;以厄他培南作为底物,阳性68株,阴性52株。与PCR结果相比,三者的灵敏度分别是98.9%(92/93),90.3%(84/93),69.9%(65/93),差异有统计学意义(χ~2=18.43,P<0.01);三者的特异度均为88.9%(24/27)。3种底物的一致率分别为96.7%,90.0%,74.2%,Kappa值分别是0.90,0.73,0.44。在4个不同孵育时间下,灵敏度分别为46.2%(43/93)、58.1%(54/93)、90.3%(84/93)和90.3%(84/93),孵育2h和0.5、1h结果相比差异有统计学意义(χ~2=27.31,P<0.05)。结论亚胺培南、美罗培南CIM试验灵敏度和一致率均高于厄他培南,可作为合适的底物,同时2h为最佳孵育时间。

Evaluation of Carbapenem-Resistant Enterobacteriaceae by CIM test under different conditions

Objective To evaluate the different ability of different substrates and different incubation times to screen carbapenem inactivation method(CIM)for carbapenem enzyme phenotype of Enterobacteriaceae bacteria.Methods Imipenem,meropenem and ertapenem were used to perform CIM test on 120 strains of Enterobacteriaceae bacteria resistant to carbapenem antibiotics.With meropenem as the indicator substrate,0.5,1,2 and 4 hours were incubates for CIM test.PCR and sequencing were used to detect whether the strain carried carbapenam-related genes.Results Of the 120 CRE strains,93 positive strains and 27 negative strains were detected by PCR,while 95 positive strains and 25 negative strains were detected by imipenem,87 positive strains and 33 negative strains were detected by meropenem and 68 positive strains and 52 negative strains were detected by ertapenem.Compared with the PCR results,the sensitivity of the three was 98.9%(92/93),90.3%(84/93),69.9%(65/93),respectively,the difference was statistically significant(χ~2=18.43,P<0.01).The specificity was 88.9%(24/27).The consistency rates of the three substrates were 96.7%,90.0% and 74.2%,respectively,and the Kappa values were 0.90,0.73,and 0.44.At four different incubation time,the sensitivity were 46.2%(43/93),58.1%(54/93),90.3%(84/93)and 90.3%(84/93),respectively.The difference was statistically significant(χ~2= 27.31,P<0.05)between 0.5,1 and 2 hours.Conclusion Imipenem and meropenem are more sensitive and consistent than ertapenem in CIM test,which can be used as suitable substrates,and 2 hours is the best incubation time.