ESBLs大肠埃希菌和肺炎克雷伯杆菌整合子分布及其与ESBLs基因关系研究

目的研究整合子在院内感染ESBLs大肠埃希菌和肺炎克雷伯杆菌中的分布及其与细菌耐药的相关性,探讨Ⅰ类整合子在ESBLs基因水平转移中的作用及其与ESBLs基因型的关系。方法运用K-B法,纸片扩散法,PCR,接合传递试验、套式PCR、质粒谱分析及DNA测序研究携带耐药基因的Ⅰ类整合子与耐药播散的关系。结果产ESBLs和非产ESBLs菌株中Ⅰ类整合酶扩增阳性例数分别是70例（占66.7%）和22例（占22.4%）,2组整合子阳性率差异有统计学意义（P〈0.01）。整合子阳性组中ESBLs、多重耐药菌均明显高于阴性组。产ESBLs菌株中blaSHV、blaCTX和blaTEM基因与整合子经质粒共同转移的频率分别是79.3%、58.5%和45.1%。结论整合子在产ESBLs大肠埃希菌和肺炎克雷伯杆菌中的分布明显高于非产ESBLs菌株,主要为Ⅰ类整合子,并参与产ESBLs菌株多重耐药性的形成,其中blaSHV基因型与整合子经质粒共同转移的频率高于其他两类基因,提示SHV型酶在浙南地区具有更强的扩散优势。

Integron and its correlation with genes coding for ESBLs-producing E.coli and K.peumoniae isolates

Objective To investigate the distribution of integron in extended-spectrum beta-lactamases（ESBLs）-producing E.coli and K.pneumoniae caused nosocomial infection and its association with drug resistance,as well as its contribution in horizontal transfer of ESBLs genes. Method K-B method,double-disk synergy test,polymerase chain reaction（PCR）,conjugative transfer test,plasmid profile analysis,nested-PCR,and DNA sequence analysis were used to research the integron mediated transfer mechanism of resistance. Result 70（66.7%） strains among ESBLs-producers were shown to be positive for classⅠintegron,contrasted to 22 （22.4%） in non-ESBLs-producers （P0.01）.The rates of transconjugation of integron together with blaSHV,blaCTX and blaTEM were 79.3%,58.5% and 45.1%,respectively. Conclusion Drug resistance are more liable to horizontal transfer via class Ⅰintegron along with plasmid. Distribution of classⅠintegron in ESBLs-producing strains is more predominant than that in non-ESBLs-producers,which contributes to multidrug resistance in ESBLs-producing strains. BlaSHV are more liable to transfer via plasmid along with classⅠintegron in south Zhejiang.