中国引起抗生素相关性腹泻艰难梭菌A、B毒素毒力及与菌株基因背景关联性研究

艰难梭菌感染是诱发抗生素相关性腹泻（AAD）的主要原因之一，治愈率低、复发率高，是全球瞩目的重大医学挑战。在我国，艰难梭菌感染的流行病学及菌株毒力资料极为匮乏，对二者间是否具有相关性更不明了，因而极大影响了临床的实践与管理。本课题将首先对收集自多中心的艰难梭菌菌株，使用核糖体分型、多位点序列分型等核酸分析技术进行基因分型，结合菌株临床资料阐明其流行病特征。检测菌株是否携带毒素编码基因及相关调控基因，分析A、B毒素基因的多态性，并对相关基因的表达情况进行比较。围绕发现的差异，通过高通量测序对代表性菌株的基因背景进行精细分析。同时，建立艰难梭菌临床分离株A、B毒素的体外表达体系，并通过构建细胞模型，测定菌株毒素毒力。据此明确我国AAD患者中艰难梭菌的毒力，并阐明毒力与菌株流行病学及基因背景的相关性，推动我国临床在艰难梭菌感染领域诊断、治疗、管理及感控方面的科学化发展。

Clostridium difficile is one of the major causes of antimicrobial-associated diarrhea (AAD), which is of low cure rate and high possibility of recurrence. The pathogen has become a huge medical challenge world-wide. In China, the epidemiology and virulence of Clostridium difficile clinical strains remain unclear, which significantly obstruct relevant clinical practice and management. In this study, we plan to characterize the epidemiology of Clostridium difficile isolates collected from multi-centers, by the combination using of isolates’ clinical information and genotyping by multiple molecular tools, e.g. PCR-ribotyping and multilocus sequence typing. Then we’ll detect the carriage of toxin-encoding and related regulating genes in isolates, analyze the genetic polymorphisms of toxin genes, and compare the expression of toxin genes in different strains. Based on results from above studies, the genetic background of representative Clostridium difficile isolates will be analyzed and compared by high-throughput sequencing techniques. Meanwhile, in vitro expression system will be developed for obtaining toxins A and B from clinical isolates, and virulence of toxins will be further determined by cell model-based experiments. Through the project, we plan to illustrate the pathogenicity of Clostridium difficile isolates in AAD patients in China, and the potential relationship between isolates’ pathogenicity, epidemiology and genetic background. We hope our results will promote the scientific development in clinical treatment, management and control of Clostridium difficile infections in China.