ISEcp1B介导铜绿假单胞菌CTX-M型ESBLs传播的分子机制研究

Study on the molecular mechanism of the dissemination of ISEcp1B mediated CTX-M-Type extended spectrum beta-lactamase-producing Pseudomonas aeruginosa

目的了解CTX-M型超广谱β-内酰胺酶(ESBLs)在铜绿假单胞菌传播的分子机制。方法用K ir-by-Bauer(K-B)药敏法分析26株铜绿假单胞菌的耐药性;用多重聚合酶链式反应(PCR)扩增ESBLs、ISEcp1B插入序列及I类整合子;用套式PCR在Ⅰ类整合子寻找β-内酰胺酶基因盒。结果26株多重耐药铜绿假单胞菌对下列抗生素的耐药率为:(1)头孢噻肟(69.23%)、哌拉西林(65.38%)、替卡西林/克拉维酸(65.38%)、头孢他啶(57.69%)、头孢吡肟(46.15%)、环丙沙星(50.00%)、氨曲南(46.15%)、阿米卡星(34.62%)、亚胺培南(30.77%)、头孢哌酮/舒巴坦(23.08%);(2)11株铜绿假单胞菌中检出CTX-M-G1,其中4株同时检出TEM、SHV、CTX-M-G1、ISEcp1B及I类整合子,I类整合子内未扩增出β-内酰胺酶;(3)ISEcp1B下游均连接CTX-M型ESBLs,ISEcp1B右端有一个反向重复序列,为转位酶提供作用位点;-35及-10位点各有一个启动子,对下游不同的CTX-M型ESBLs的高水平表达和传播起重要的调控作用。结论ISEcp1B可能对下游CTX-M型ESBLs的高水平表达和传播起重要的调控作用。

Objective To investigate the molecular mechanism of dissemination of the CTX-M extended spectrum beta-lactamase （ESBLs） producing Pseudomonas aeruginosa （PAE）. Methods Kirby-Bauer susceptibility method was used to analyze the drug resistance of 26 isolates ;gene of ESBLs,insertion sequence ISEcp1B and integron Ⅰ were amplified by multiple polymerase chain reaction （PCR） ;beta-lactamase gene was detected and located in the integron Ⅰby the Nest- PCR. Results （ 1 ） Susceptibility test showed their resistance from high to low were Cefotaxime （ 69.23 % ）, Piperacillin （65. 38 % ）, Ticarcillin/Clavulanic acid （65. 38% ）, Ceftazidime （57. 69% ）, Cefepime （46. 15% ）, Ciprofloxacin （ 50.00% ）, Aztreonam（46.15% ）, Amikacin （ 34.62% ）, Imipenem （ 30.77% ）, Cefoperazone/Sulbactam （ 23.08% ）, respectively;PAE was susceptive to Amikacin, Imipenem and Cefoperazone/Sulbactam. （2） CTX-M-G1 was found in 11 strains of PAE; TEM, SHV, CTX-M-G1, ISEcp1B and integron Ⅰ were found in 4 isolates; there was no beta latamase in the integron Ⅰ. （3）blaCTX-M-like was flanked upstream by an ISEcp1B element provided a right inverted repeat （IRR） recognized by tansposase;-35 and -10 promoter sequences may drive the expression and dissemination of blaCTX-M-like gene at a high level. Conclusion ISEcp1B may drive the expression and dissemination of the different blaCTX-M-like gene at a high level