How Antibiotics Impact Bile Acid Composition & Can Result in CDI

Norman B. Javitt, MD, PhD, research professor of medicine and pediatrics at NYU School of Medicine, explains how antibiotics can impact bile acid composition and result in Clostridium difficile infection.

Interview Transcript (modified slightly for readability):

“The relationship of antibiotics to changes in bile acid composition are that the bacteria normally make two important enzymes that convert primary bile acids made in the liver to secondary bile acids that are formed in the intestines. And when you reduce the level of those bacteria, then you lose the enzymes.

Now, the startling advance in understanding the cause of C. difficile is that primary bile acids coming from the liver cause the germination of the dormant spores in the intestine and allow for the vegetative forms to produce toxins. Secondary bile acids block that so that people who may normally have spores in their large intestine, the spores are dormant because the secondary bile acids keep them from germinating. And when you abolish their production because of antibiotics, the spores begin to develop vegetative forms and form toxins.

And the evidence now is when you do FMT, fecal microbiota transplant, you restore the normal relationship of secondary to primary bile acids. Because in large population studies, over 70-90% of the bile acids in the colon are secondary bile acids and that’s what’s keeping us healthy.”