Douglas A. Drossman, MD: Defining the Relationship Between the Gut and Brain

When we look at the functional GI disorders — we now call them disorders of the brain-gut interaction because we're looking at how the brain and gut are talking to each other — there's no organ that's as closely connected to the brain as the gut, because it has its own nervous system. The brain and the gut regulate each other, and that can lead to problems in terms of pain, diarrhea, or constipation, if that's not working right.

Another interesting component, more recently, is what we call the microbiome. In many ways, we're just beginning to understand how much the bacteria might play a role in gut function in terms of its integrity, in terms of susceptibility to disease — certainly infectious diseases, as well as irritable bowel. If you have altered bacteria or an infection, you might develop irritable bowel syndrome.

We also know that the bacteria may even play a role in psychiatric functioning. There are animal models to show us how so-called bad bacteria can induce difficulties in mental functioning. The idea of this interaction has relevance from the microbiome to the neuroplexus of the gut, to the brain.

Trulance is one of the chloride channel agents like linaclotide, lubiprostone. It may reduce the amount of diarrhea that can occur with some of the other drugs, but it acts at chloric channel and it's been shown to improve the constipation, increase the number of spontaneous bowel movements, and reduce the pain.

C. difficile, when it first came out, was pretty limited to a narrow spectrum of antibiotics. Clindamycin was the first one, and it's a bacteria that then overgrows as a result of the antibiotic reducing the other bacteria. Over time, what we started to see is the broader spectrum of bacteria, particularly in hospital settings with older, post-operative patients. I wouldn't say it's growing a high levels extremely fast, but it's growing considerably. With that, what we're finding is there can be resistances.

So about 15% or 20% of patients who get treated develop it again because they have spores. So when you treat the bacteria, the spores continue and later it comes out again. One of the big problems these days is many of these patients have to be retreated, and as you have a greater number of people getting it, you have a greater number of people having resistance C. difficile.

I think the new kid on the block is looking at fecal transplant because that has been shown to be very effective for these patients who are refractory to repeated treatment, usually with vancomycin.