VITEK-2 Compact高级专家系统对CTX-M型超广谱β-内酰胺酶的检测分析

Detection of CTX-M extended spectrum beta-lactamases with VITEK 2 Compact AES

目的评估VITEK-2Compact(V2C)高级专家系统(AES)对CTX-M型ESBLs的检测分析能力。方法随机抽取2010年1-8月AES所提示的产ESBLs菌株194株,进行CTX-M表型分析,并与聚合酶链反应(PCR)方法加以比较。结果 194株产ESBLs菌株经AES提示CTX-M型94株,检出率为48.5%,PCR证实携带CTX-M基因型164株,检出率为84.5%,差异有统计学意义(P<0.05);AES报告的94株CTX-M型产ESBLs,经PCR确认为89株,头孢他啶MIC值≤1μg/ml占95.5%,其耐药表型以CTX-M型为主,而漏检的75株中,头孢他啶MIC值≤1μg/ml只占2.7%,其耐药表型大肠埃希菌以产ESBLs为主,肺炎克雷伯菌以产ESBLs或ESBLs+膜渗透障碍为主;AES与PCR漏检株对氨曲南、头孢他啶、头孢吡肟耐药率要高于符合株。结论 AES对混合型耐药机制的CTX-M型产ESBLs检测有一定的漏检;如需进一步进行产ESBLs的亚型研究或相关流行病学调查,仍需要以分子生物学方法进行验证。

OBJECTIVE To explore the detection of CTX-M extended spectrum beta-lactamase（ESBLs） with VITEK-2 Compact AES.METHODS A total of 194 positive ESBL-producing strains were randomly selected from Jan to Aug 2010,then the CTX-M phenotype analysis was performed for those strains,the result was compared with polymerase chain reaction（PCR） method.RESULTS Of 194 ESBL-producing strains,94 strains carrying CTX-M type were suggested by AES with the detection rate of 48.5%,and 164 strains carrying CTX-M genotype were confirmed by PCR with the detection rate of 84.5﹪,the differences was statistically significant（P0.05）;of 94 ESBL-producing strains of genotype CTX-M reported by AES,there were 89 strains confirmed with PCR,the strains with the ceftazidime MIC value less than 1 μg/ml accounted for 95.5%,the drug resistant phenotype was dominated by CTX-M type;of 75 strains of missing examination,the strains with the ceftazidime MIC value less than 1 ug/ml accounted for only 2.7%,the resistant phenotype was dominated by ESBL-producing Escherichia coli,ESBLs or ESBLs ＋ membrane permeability barriers were dominant in Klebsiella pneumoniae;the resistance rates of the strains of missing examination were higher than those accordant strains to aztreonam,ceftazidime,and cefepime.CONCLUSION There is certain missing of the detection of complex resistance mechanisms of CTX-M ESBLs-producing strains with AES;if the further study of ESBLs subtype or related epidemiological investigation is needed,molecular biology method for the validation remains necessary.