Geric Barbara, Carman Robert J, Rupnik Maja, Genheimer Christopher W, Sambol Susan P, Lyerly David M, Gerding Dale N, Johnson Stuart
Department of Biology, University of Ljubljana, Ljubljana, Slovenia.
J Infect Dis. 2006 Apr 15;193(8):1143-50. doi: 10.1086/501368. Epub 2006 Mar 6.
Binary toxin CDT or its genes have been identified in some strains of Clostridium difficile that also produce the large clostridial toxins, toxins A and B (A+B+CDT+), including a newly recognized epidemic strain in the United States and Canada. To study the effects of binary toxin alone, we characterized 4 binary toxin CDT-positive only (A-B-CDT+) C. difficile strains. Unlike other clostridial binary toxins, binary toxin CDT required exogenous trypsin for activation. Supernatants from all A-B-CDT+ strains caused marked fluid accumulation in the rabbit ileal loop assay after concentration and trypsinization. In addition, the ileal loop response was neutralized by antisera raised against other binary toxin-producing clostridia. Challenge of clindamycin-treated hamsters with these strains resulted in colonization but not diarrhea or death. Binary toxin CDT may play an adjunctive role to toxins A and B in the pathogenesis of C. difficile-associated disease but by itself may not be sufficient to cause disease.
二元毒素CDT或其基因已在一些艰难梭菌菌株中被鉴定出来，这些菌株还会产生大型梭菌毒素、毒素A和毒素B（A+B+CDT+），包括在美国和加拿大新发现的一种流行菌株。为了单独研究二元毒素的作用，我们对4株仅产二元毒素CDT阳性（A-B-CDT+）的艰难梭菌菌株进行了特性分析。与其他梭菌二元毒素不同，二元毒素CDT需要外源性胰蛋白酶来激活。所有A-B-CDT+菌株的上清液在浓缩和胰蛋白酶处理后，在兔回肠袢试验中引起明显的液体蓄积。此外，回肠袢反应被针对其他产二元毒素梭菌产生的抗血清中和。用这些菌株对经克林霉素处理的仓鼠进行攻毒，导致了定植，但未引起腹泻或死亡。二元毒素CDT在艰难梭菌相关性疾病的发病机制中可能对毒素A和B起辅助作用，但单独作用可能不足以引起疾病。
