Clostridium difficile colitis does not happen in a vacuum. When, why and how C. diff populations explode and cause colitis is the result of a complex interplay among bacteria, human host, the gut microbiome and the environment.

Several experts will examine how C. diff causes disease during Tuesday’s AGA Translational Symposium Clostridium difficile Colitis: When Good Bugs Go Bad. The goal is to help gastroenterologists better deal with the problem or avoid C. diff overgrowth in the first place, according to symposium co-moderator Darrell S. Pardi, MD, MS, AGAF, professor of medicine at the Mayo Clinic, Rochester, MN.

“We’ve seen evidence over the past 20 years that C. diff is becoming more common, more severe and is responsible for a growing number of deaths,” Dr. Pardi said. “We don’t have great treatments, which makes it all the more important to understand the factors that affect C. diff so we can manage it more effectively.”

The session’s presenters will discuss microbial therapy for C. diff infection, microbiota functions that are associated with C. diff susceptibility, and the role of host-microbiota crosstalk in the development and treatment of C. diff colitis.

“We used to think of the human microbiome as stool and waste. Now we realize that it has a lot of important functions for the immune system, metabolism, nutrition and protecting us from bad bugs,” Dr. Pardi said. “Looking at C. diff provides a useful model for studying the microbiome and how it affects human conditions.”

One of the challenges of C. diff is its tendency to recur. Recurrence, like an initial infection, is affected by a variety of host and environmental factors.

“Fecal microbiota transplantation [FMT] is the most effective tool available to deal with recurrent C. diff infection,” Dr. Pardi said. “And while FMT is usually successful, a number of clinical and microbiological factors are beginning to emerge that are associated with both success and failure of the transfer. Altered diversity in phage populations in the gut, for example, is associated with FMT failure.”

How FMT is administered may also play a role, Dr. Pardi noted. Many gastroenterologists administer FMT via colonoscopy, but oral administration may be an effective alternative. Results from one of the few head-to-head trials comparing colonoscopic to capsule delivery of FMT will be reviewed during Tuesday’s symposium.

“Every gastroenterologist needs to know about the occurrence and treatment of C. diff. Almost all of our patients — inpatients and outpatients — are at risk for C. diff infection,” Dr. Pardi said. “The microbiome is emerging as an important player not just in C. diff, but in most, maybe all, GI diseases. Few areas in GI are changing as rapidly as our understanding of the microbiome and the role it plays in a variety of diseases.”

Please refer to the DDW Mobile App or the Program section in Tuesday’s DDW Daily News for additional details on this and other DDW^® events.