Intestinal calcium and bile salts facilitate germination of Clostridium difficile spores

PLoS Pathogens

Ashley D. Smith¹  Jessica L. Hastie¹  Alyxandria M. Schubert¹  Paul E. Carlson Jr¹  Nicole P. Giordano¹  Philip C. Hanna²  Madeline J. Somers²  Ada K. Hagan²  Alyssa M. Kaiser²  Travis J. Kochan²  Michelle S. Shoshiev² 

[1] Center for Biologics Evaluation and Research, US Food and Drug Administration. Silver Spring, Maryland, United States of America;University of Michigan Medical School, Department of Microbiology and Immunology. Ann Arbor, Michigan, United States of America

关键词: Bacterial spores;    Clostridium difficile;    Glycine;    Gastrointestinal tract;    Mouse models;    Calcium signaling;    Antibiotics;    Colorimetric assays;   

DOI  :  10.1371/journal.ppat.1006443

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Clostridium difficile (C. difficile) is an anaerobic gram-positive pathogen that is the leading cause of nosocomial bacterial infection globally. C. difficile infection (CDI) typically occurs after ingestion of infectious spores by a patient that has been treated with broad-spectrum antibiotics. While CDI is a toxin-mediated disease, transmission and pathogenesis are dependent on the ability to produce viable spores. These spores must become metabolically active (germinate) in order to cause disease. C. difficile spore germination occurs when spores encounter bile salts and other co-germinants within the small intestine, however, the germination signaling cascade is unclear. Here we describe a signaling role for Ca2+ during C. difficile spore germination and provide direct evidence that intestinal Ca2+ coordinates with bile salts to stimulate germination. Endogenous Ca2+ (released from within the spore) and a putative AAA+ ATPase, encoded by Cd630_32980, are both essential for taurocholate-glycine induced germination in the absence of exogenous Ca2+. However, environmental Ca2+ replaces glycine as a co-germinant and circumvents the need for endogenous Ca2+ fluxes. Cd630_32980 is dispensable for colonization in a murine model of C. difficile infection and ex vivo germination in mouse ileal contents. Calcium-depletion of the ileal contents prevented mutant spore germination and reduced WT spore germination by 90%, indicating that Ca2+ present within the gastrointestinal tract plays a critical role in C. difficile germination, colonization, and pathogenesis. These data provide a biological mechanism that may explain why individuals with inefficient intestinal calcium absorption (e.g., vitamin D deficiency, proton pump inhibitor use) are more prone to CDI and suggest that modulating free intestinal calcium is a potential strategy to curb the incidence of CDI.

【 授权许可】

CC BY