中美艰难梭菌A-B+株毒力编码区域转录及B毒素表达的研究

Comparison of transcriptions of pathogenicity locus genes and expressions of toxin B of A-B+ Clostridium difficile between China and the United States

摘要:

目的研究中国艰难梭菌A-B+型分离株BJ08和美国艰难梭菌A-B+型暴发流行株US1的毒力编码区域PaLoc各基因转录及B毒素的表达，为预防和控制中国可能暴发的艰难梭菌感染提供理论支持。方法每隔3 h提取BJ08与US1艰难梭菌和培养上清，用荧光定量聚合酶链反应（PCR）法测定各时间段两菌株毒力编码区域PaLoc各基因（tcdA、tcdB、tcdC、tcdR、tcdE）的表达；用酶联免疫吸附试验（ELISA）法检测BJ08和US1各时间段的细胞和培养液上清中B毒素的含量。结果US1的生长速率稍快于BJ08，衰退速率显著快于BJ08（P＜0.05）；它们都不表达A毒素，但是都检测到tcdA基因的转录，而且tcdA转录没有明显差异。BJ08的tcdB、tcdC和tcdE基因的转录要比US1早3 h。B毒素在两种菌株的胞内和胞外合成或分泌没有明显差异。结论中国艰难梭菌A-B+型高分离株BJ08与美国艰难梭菌A-B+型暴发流行株US1相比，有相似的毒力表达或更强的基因调控能力，要警惕中国艰难梭菌BJ08暴发流行的可能。

关键词:

艰难梭菌; 毒力编码区; PaLoc; B毒素; 抗生素相关腹泻; 假膜性肠炎; 医院感染

Abstract:

ObjectiveTo study gene transcriptions of pathogenicity locus (PaLoc) and toxin B expressions of A-B+ Clostridium difficile （C. difficile）strain BJ08 isolated in China and strain US1 isolated in C. difficile infection outbreak regions in the United States, and provide theoretical support for prevention and control of possible outbreak of C. difficile infection in China.MethodsCells and supernatants of C. difficile were collected every 3 hours, gene expressions of PaLoc domain, including tcdA, tcdB, tcdC, tcdR and tcdE genes, were detected by realtime polymerase chain reaction (PCR), the expressions of toxin B in cells and supernatants were detected by enzymelinked immunosorbent assay (ELISA).ResultsThe growth rate of strain US1 was slightly faster than that of BJ08, and the degradation rate of US1 was significantly faster than that of BJ08（P＜0.05）; No toxin A was detected but mRNA of tcdA were detected in both BJ08 and US1, and there was no significant difference in tcdA expression between BJ08 and US1. The transcriptions of tcdB,tcdC and tcdE of BJ08 were 3 hours earlier than those of US1. There was no significant difference in the production of toxin B in supernatants and cells between strain BJ08 and US1.ConclusionCompared with US1, there is similar virulence or stronger gene regulation of BJ08, possible outbreak of C.difficile infection in China should be alerted.

Key words:

Clostridium difficile; pathogenicity locus;toxin B;antibioticassociated diarrhea; pseudomembrane colitis;healthcareassociated infection