Intestinal calcium and bile salts facilitate germination of Clostridium difficile spores

 

Travis J. Kochan1, Madeline J. Somers1, Alyssa M. Kaiser1, Michelle S. Shoshiev1, Ada K. Hagan1, Jessica L. Hastie2, Nicole P. Giordano2, Ashley D. Smith2, Alyxandria
M. Schubert2, Paul E. Carlson, Jr2, Philip C. Hanna1*

PLoS Pathog 13(7): e1006443 (July 13, 2017)

Speaker: Yu-Shan Lin (林鈺珊)             Time: 15:00~16:00, Nov. 15, 2017

Commentator: Dr. Po-Lin Chen (陳柏齡 老師) Place: Room 601

 

Abstract:

    Clostridium difficile (C. difficile) is a gram-positive, spore-forming obligate anaerobic bacteria. The symptoms of C. difficile infection (CDI) include antibiotic-associated diarrheas (AAD), pseudomembranous colitis and toxic megacolon. CDI typically occurs after ingestion of infectious spores by patients that have been treated with broad-spectrum antibiotics. In these patients, C. difficile spore become metabolically active (germinate) to cause disease. Previously, spore germination was found to require intestinal bile salts [1]. However, whether additional germination signals exist is unclear. Previous study has demonstrated that calcium and dipicolinic acid (Ca-DPA) act as a germination signal to activate cortex hydrolysis in another spore forming bacteria, Bacillus spp. [2]. In this study, the authors investigated whether or not exogenous Ca-DPA can induce C. difficile spore germination. Second, the authors also test other actions (Mg2+, Na+, Zn2+, K+, and Li+) c  ould stimulate C. difficile germination. Furthermore, to directly test if intestinal calcium plays a role in C. difficile spore germination, the author collected ileal content from antibiotic-treated, non-infected mice (calcium-depleted) to perform ex vivo germination assay. The result of ex vivo experiment indicates that calcium in the intestines is required for efficient C. difficile spore germination. These  is a first report to find out that calcium plays an important role within C. difficile spore germination. The intestinal calcium coordinates with bile salts to stimulate spore germination. These findings also provide a potential strategy to suppress CDI.

References：

1. Sorg JA, Sonenshein AL (2008) Bile salts and glycine as cogerminants for Clostridium difficile spores. J Bacteriol 190: 2505–2512.

2. Paredes-Sabja D, Shen A, Sorg JA (2014) Clostridium difficile spore biology: sporulation, germination, and spore structural proteins. Trends Microbiol 22: 406–416.