奇异变形杆菌耐药基因岛在动物源性食品中的分布及水平转移机制研究

Horizontal transfer mechanism of movable resistance gene elements has been recognized the focus of the research in recent years. However, the transfer mechanism of Salmonella Genomic Island 1 (SGI1) with integrons and multidrug-resistant genes has not yet been clarified. Also, Proteus mirabilis transfer resistance genes as SGI1 donor strain have not been reported by far. This topic is to detect SGI1 in P. mirabilis strains isolated from animal-derived food, assess the role of extrachromosomal circular form of SGI1, the helper plasmid, int integrase gene and xis excisionase gene in transfer of SGI1 by the technique of molecule biology, analyze the integration and excision sites for SGI1, after conjugal transfer, find the changes in sequences of SGI1, donor and recipient chromosome, reveal the horizontal transfer mechanism of SGI1 in P. mirabilis, based on the SGI1-carrying P. mirabilis strains and a helper IncC plasmid R55. The topic is to obtain the distribution of SGI1 in P. mirabilis animal-derived food isolates from China, and clarify the mechanism of SGI1 disseminated in a new perspective, in order to provide new targets for inhibiting the multidrug resistance of food-borne pathogens.

可移动耐药基因元件的水平传播机制已成为近年研究的热点，然而同时含有整合子和多个耐药基因的耐药基因岛SGI1的转移机制尚未阐明，奇异变形杆菌(Proteus mirabilis)作为SGI1供体菌传递耐药基因的研究，迄今国内外尚无报道。本课题拟检测我国动物源性食品中污染的P. mirabilis携带SGI1的情况，并以携带SGI1的菌株和辅助质粒IncC R55为基础材料，通过分子生物学手段，分析SGI1在染色体外的环状结构、辅助质粒、整合酶int基因和切除酶xis基因对SGI1水平转移的影响，研究SGI1发生整合切除的位点及整合后SGI1基因序列、供体菌和受体菌染色体基因组的变化，揭示P. mirabilis中SGI1水平转移的机制。本课题将总结P. mirabilis携带的SGI1在我国动物源性食品中的分布规律，从新的视角阐明SGI1播散的机制，为食源致病菌多重耐药的控制提供新的靶点。

可移动耐药基因元件的水平传播机制已成为近年来研究的热点，然而同时含有整合子和多个耐药基因的耐药基因岛(Salmonella Genomic Island 1, SGI1)的转移机制尚未阐明，奇异变形杆菌(Proteus mirabilis)作为SGI1供体菌传递耐药基因的研究，迄今国内外尚无报道。项目组成员采集临床样品和大量的肉制品、乳制品，建立了基于PCR、免疫技术、上转换发光纳米技术和表面增强拉曼光谱技术等一系列快速检测方法，从中分离检测了包括P. mirabilis、空肠弯曲菌、结肠弯曲菌、副溶血性弧菌、弓形菌、黄曲霉毒素在内的常见致病菌、真菌毒素以及抗生素残留，并分离了SGI1及其变异体。以携带这些SGI1的P. mirabilis多重耐药菌株和辅助质粒IncC R55为基础材料，通过分子生物学手段，分析了SGI1在染色体外的环状结构、辅助质粒、整合酶int基因和切除酶xis基因对SGI1水平转移的影响、SGI1发生整合切除的位点以及整合后SGI1基因序列、供体菌和受体菌染色体基因组变化情况，阐明了动物源性食品污染的P. mirabilis携带SGI1的分布状况和水平转移机制，对一些抗生素的有效合理使用和开发新型抑制细菌耐药性方法研究提供指导。