携带SXT/R391家族整合接合元件多重耐药菌株的高效筛选与分析

Effective Screening for Multiple-Drug Resistant Bacteria Harboring SXT/R391 Family of Integrative and Conjugative Elements

本研究建立了一种抗生素平板与分子检测相结合的高效筛选水产品中携带SXT/R391家族整合接合元件(integrative and conjugative elements,ICEs)的多重耐药菌株的方法。采用美国临床与实验室标准研究所标准Kirby-Bauer纸片扩散法、需氧菌液体微量稀释法,以及接合实验,对筛选、鉴定获得的携带SXT/R391家族ICEs的变形杆菌(Proteus vulgaris)进行了抗菌素、重金属抗性以及ICEs元件接合转移活性的分析。结果表明:运用本研究建立的筛选法可有效获得含有多重耐药基因的ICEs元件,其检出率为3%,远高于常规聚合酶链式反应技术的检测水平(<1‰)。受试菌株对六大类10种抗菌素均表现出抗性,并且对重金属镉、铜、锌和汞具有高度耐受性。接合实验证明了受试菌株所携带的ICEs元件在普通变形杆菌与大肠杆菌(Escherichia coli)MG1655之间的自我转移活性。

In this study,we established a highly effective method to screen multiple-drug resistant（MDR） bacteria carrying the integrative and conjugative elements（ICEs）.Five Proteus vulgaris strains harboring SXT/R391 family of ICEs,isolated from aquatic products in Shanghai,China,were obtained using the new method.Antimicrobial activity and heavy metal susceptibility of the P.vulgaris strains were examined using standard Kirby-Bauer disk diffusion method and dilution susceptibility tests according to the Clinical and Laboratory Standards Institute（CLSI,USA,2012 Edition）,all showing distinct resistance to ten antimicrobial agents belonging to six drug classes tested.In addition,a wide heavy metal resistance profile was also detected,displaying strong resistance to Cd,Cu,Zn and Hg.The conjugation experiments demonstrated the capacities of active self-transmission of the SXT/R391-like ICEs between P.vulgaris and Escherichia coli MG1655 strains.Our results will facilitate further research on collaborative selection mechanism of environmental antibiotics and heavy metals,and early warning in prevalence of novel MDR bacteria or ＂super bacteria＂.