Impact of Primary and Secondary Bile Acids on Clostridioides difficile Infection

Primary bile acids (BAs), synthesized from cholesterol in the liver, after their secretion with bile into the intestinal lumen, are transformed by gut microbiota to secondary BAs. As natural detergents, BAs play a key role in the digestion and absorption of lipids and liposoluble vitamins. However, they have also been recognized as important signaling molecules involved in numerous metabolic processes. The close bidirectional interactions between BAs and gut microbiota occur since BAs influence microbiota composition, whereas microbiota determines BA metabolism. In particular, it is well established that BAs modulate Clostridioides difficile life cycle in vivo. C. difficile is a cause of common nosocomial infections that have become a growing concern. The aim of this review is to summarize the current knowledge regarding the impact of BAs on the pathogenesis, prevention, and treatment of C. difficile infection.