Journal Article

Intestinal calcium and bile salts facilitate germination of Clostridium difficile spores

Kochan, Travis J., Carlson, Paul E., Hagan, Ada K., Hastie, Jessica L., Somers, Madeline J., Schubert, Alyxandria M., Hanna, Philip C., Shoshiev, Michelle S., Giordano, Nicole P., Smith, Ashley D., Kaiser, Alyssa M.

2017

Overview

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.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Adenosine triphosphatase / Animal models / Animals / Antibiotics / Bacteria / Bacterial diseases / Bacterial infections / Bacterial Proteins - metabolism / Bile Acids and Salts - metabolism / Bile salts / Biology and Life Sciences / Calcium / Calcium - metabolism / Calcium absorption / Calcium ions / Calcium Signaling / Calcium signalling / Care and treatment / Clostridium difficile - genetics / Clostridium difficile - growth & development / Clostridium difficile - metabolism / Clostridium infections / Clostridium Infections - metabolism / Clostridium Infections - microbiology / Coding / Colonization / Development and progression / Disease transmission / Fluxes / Food / Funding / Gastrointestinal system / Gastrointestinal tract / Germination / Glycine / Hospitals / Host-bacteria relationships / Humans / Immunology / Incidence / Infections / Ingestion / Intestine / Intestine, Small - metabolism / Intestine, Small - microbiology / Medical research / Medical schools / Medicine and Health Sciences / Medicine, Experimental / Mice / Mice, Inbred C57BL / Nosocomial infection / Nosocomial infections / Nutrient deficiency / Pathogenesis / Pathogens / Physical Sciences / Proton pump inhibitors / Research and Analysis Methods / Rodents / Roles / Salts / Small intestine / Spore germination / Spores / Spores, Bacterial - genetics / Spores, Bacterial - growth & development / Spores, Bacterial - metabolism / Supervision / Toxins / Virulence (Microbiology) / Vitamin D / Vitamin deficiency