临床分离摩氏摩根菌中整合子分布特征及耐药相关性分析

Distribution characteristics and drug resistance correlation analysis of integron in clinically isolated Morganella morganii

目的了解某医院临床分离的摩氏摩根菌整合子的分布情况和整合子阳性菌株可变区耐药基因盒的分子特征及其与耐药性的关系。方法收集该院2015年11月—2021年8月临床分离的非重复摩氏摩根菌97株,通过PCR技术进行第1、2、3类整合子筛查,用ERIC-PCR的方法对整合子阳性菌株进行同源性分析。结果97株摩氏摩根菌中有28株第1类整合子阳性菌株,占28.9%。第2类整合子阳性菌株5株,占5.2%,其中有1株同时携带第1类和第2类整合子,未检出第3类整合子。32株整合子阳性菌株中26株可变区检测到扩增产物,其中第1类整合子阳性菌株可变区携带的耐药基因盒主要为dfrA17-aadA5,第2类整合子阳性菌株可变区携带的耐药基因盒主要为dfrA1-sat2-aadA1;整合子阳性菌株对复方新诺明、氨苄西林/舒巴坦和环丙沙星的耐药率分别为90.6%、81.3%和78.1%,均高于整合子阴性菌株(P<0.05)。32株整合子阳性摩氏摩根菌主要为A和B2种基因型。结论摩氏摩根菌中以第1类整合子为主,其可变区主要携带氨基糖苷类和甲氧苄啶类抗菌药物耐药基因盒,与宿主菌耐药呈高度相关性,整合子阳性菌株间同源性较高,可能存在着院内的克隆传播。

Objective To investigate the distribution of integrons and the molecular characteristics of variable region resistance gene cassettes of integron-positive strains of Morganella morganii isolated from our hospital and their relationship with drug resistance.Methods Ninety-seven strains of non-replicated M.morganii clinically isolated from November 2015 to August 2021 at our hospital were collected and detected by PCR for class 1,2 and 3 integrons.Homology analysis of integron-positive strains was performed by ERIC-PCR.Results Among the 97M.morganii strains,28 strains were positive for class 1 integrons,accounting for 28.9%.Five strains were positive for class 2 integrons,accounting for 5.2%,of which one strain carried both class 1 and class 2 integrons,and no class 3 integrons were detected.PCR products were successfully amplified in the variable region of 26 of the 32 integron-positive strains.The drug resistance gene cassettes carried by the variable region of the class 1 integron-positive strains were mainly dfrA17-aadA5,and those carried by the variable regions of the class 2 integron-positive strains were mainly dfrA1-sat2-aadA1.The resistance rates of cotrimoxazole,ampicillin/sulbactam,ciprofloxacin were 90.6%,81.3%,78.1%,respectively,which were higher than those of integron-negative strains(P<0.05).The 32 integron-positive M.morganii strains were mainly of two genotypes,A and B.Conclusion Variable regions of class 1 integrons in M.morganii mainly carry aminoglycoside and trimethoprim drug resistance gene cassettes and are highly correlated with host bacterial drug resistance,with high homology among integronpositive strains and possible intra-hospital clone and transmission.