CTX—M型和CMY型耐药基因的检测与传播机制的探讨

Detection of CTX-M-type extended-spectrum β -lactamases and CTX- M -type AmpC ~ -lactamases resistance gene and investigation of their transmission mechanism

目的筛查广州医学院第一附属医院临床分离的80株革兰氏阴性杆菌的CTX-M型或CMy型耐药基因，检测含CTX-M型或CMY型菌株的耐药情况以及初步探讨耐药传播机制中质粒介导耐药这一途径。方法对该细菌进行总DNA的提取，PCR扩增该80株细菌的DNA。结合K-B法药物敏感试验，分析菌株的耐药特征，提取基因筛选为阳性的细菌，判定其质粒是否存在耐药基因，质粒接合试验判断是否为可接合质粒。结果检出ESBLS产酶菌CTX—M型4株，占5％，AmpC产酶菌CMY型3株，占3．75％。对耐药基因的筛选为阳性的7株菌株质粒提取，有6株菌为阳性，质粒接合试验结果显示有2株菌的质粒为可接合质粒，野生菌和接合菌的质粒中均存在耐药基因。结论CTX—M和CMY菌株呈现多重性耐药性，CTX-M和CMY菌株的耐药基因大部分位于质粒上，其中2株为可接合质粒，这一初步探讨为耐药传播机制的研究打下基础。

Objective To investigate CTX-M ESBLs or CMY AmpC β -lactamases and study transmission mechanisms of 80 strains Gram negative bacilli isolated from the first affiliated hospital of Guangzhou Medical College. Methods DNA was extracted from 80 strains Gram-negative bacilli and then was amplificated by PCR, resistant features was analysised by Kirby-Bauer disk diffusion test. Plasmid conjugation test was applied to confirm whether the plasmid could conjugate. Results The results showed that 3 strains （3.75%） were AmpC β -lactamases and 4 strains （5%） were ESBLs. Plasmid of 6 strains could be extracted, and plasmid conjugation test was positive for 2 strains. The plasmid of the wild and zygomycetes all existed resistance gene. Conclusion The strains of CTX-M and CMY had multiple resistance to antibiotic, most of the resistance gene located in Plasmid, two of those plasmid could conjugate, that lays a good foundation for transmission mechanism.