质粒介导产ESBLs与AmpC β-内酰胺酶基因弗氏柠檬酸杆菌的研究  

Molecular characterization of encoding plasmid-mediated ESBLs and AmpC β-lactamases genes in Citrobacter freundii

作　　者：陈坚[1] 余方友[1] 

机构地区：[1]温州医学院附属第一医院检验科,浙江温州325000

出　　处：《中华医院感染学杂志》2011年第21期4435-4437,共3页Chinese Journal of Nosocomiology

摘　　要：目的研究一株同时产ESBLs和AmpCβ-内酰胺酶弗氏柠檬酸杆菌(CFR)的耐药机制。方法 2008年1月从临床尿液标本中分离出多药耐药弗氏柠檬酸杆菌1株,采用双纸片扩散法检测产ESBLs,头孢西丁三维试验检测AmpC酶,E-test法测定抗菌药物最低抑菌浓度(MIC),聚合酶链反应(PCR)检测产ESBLs和AmpC酶基因,DNA测序决定基因型;接合试验测定耐药基因的转移性。结果临床分离出一株同时产ESBLs和AmpCβ-内酰胺酶的多药耐药弗氏柠檬酸杆菌,对头孢他啶、头孢噻肟、头孢西丁、氨曲南、氨苄西林、磺胺甲噁唑/甲氧苄啶的MIC分别为96、96、256、192、>256、>32μg/ml,PCR扩增及测序临床分离株携带blaCTX-M-3和blaCMY-2,接合试验显示含blaCTX-M-3和blaCMY-2基因耐药质粒可以通过接合转移至受体菌大肠埃希菌J53。结论 CFR同时携带有ESBLs和AmpCβ-内酰胺酶基因,ESBLs基因和AmpCβ-内酰胺酶基因由质粒介导。OBJECTIVE To investigate the resistant mechanism of Citrobacter freundii which coexisted with ESBLs and AmpC genes. METHODS A multi-resistant Citrobacter freundii was isolated from hospital by VITEK-60 system. The detection of ESBLs was performed by the CLSI-recommended confirmatory test, Cefoxitin three-dimentional test was presented to identify AmpC β-lactamases, the mimimal inhibitative concentration（MIC） was determined by E-test. Polymerase chain reaction（PCR） and sequencing were carried out for analyzing the encoding genes of 9-lactamases. Conjugation study was performed to determine whether resistant genes were likely transferred by plasmid, RESULTS The isolate was highly resistant to ceftazidime （MICs, 96 μg/ml）, cefotaxime （MICs,96 μg/ml）, cefoxitin（MICs,256μg/ml）, aztreonam（MICs, 192 μg/ml）, ampicillin（MICs, 〉256μg/ml） and sinomin compositea（MICs, 〉32 μg/ml）. The clinical isolate produced AmpCs and ESBLs. The presence of blacTx-M-3 and blaCMY-2 of clinical isolate were identified by PCR and sequenced. Those genes of clinical isolate could be transferred to Escherichia coli J53 through conjugation. CONCLUSION Citrobacter freundii carries ESBLs and AmpC β-lactamases genes synchronously, which were mediated by plasmid.

关 键 词：弗氏柠檬酸杆菌 产超广谱Β-内酰胺酶 CTX-M-3 AMPC β-内酰胺酶 CMY-2 

分 类 号：R378[医药卫生—病原生物学]