Dr. M. Elizabeth Tessier, a pediatric gastroenterology fellow at Texas Children’s, received the 2014 Fellow Research Award from the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN).
Her award-winning study titled, “Bile acid signatures in children confer protection from clostridium difficile infection,” found that changes in the bile acid composition in the stool may predispose patients to Clostridium difficile (C.diff), a bacterial infection that causes intestinal inflammation and diarrhea.
In general, children are less susceptible to C.diff infection than adults and tend to have milder disease. However, Tessier says pediatric cases are on the rise, which may be attributed to a newer more toxigenic strain of C. diff called NAP1.
Antibiotics disrupt the bacterial communities in the colon which can alter bile acid compositions, creating favorable conditions for C.diff spores to germinate. Certain types of bile acids can activate or inhibit the growth of this bacterium.
In their study, Tessier and her colleagues in Tor Savidge’s lab in the Texas Children’s Microbiome Center, collected stool samples to examine the bile acid profiles of healthy children between the ages of 7 and 12, healthy adults, patients with antibiotic-induced diarrhea and C.diff patients.
The healthy control group had higher levels of chenodeoxycholic acid (CDCA) – which inhibits C.diff growth – compared to the other two groups. They found healthy children had more CDCA than healthy adults, which may contribute to children’s decreased susceptibility to C.diff infection.
In contrast, patients with antibiotic-induced diarrhea, who may be prone to C.diff infection, had elevated levels of the spore-germinating bile acid called taurocholate. While C. diff patients had lower levels of both bile acid types, they had high serum levels of fibroblast growth factor 19 (FGF-19), a hormone that regulates bile acid synthesis in the liver.
“Based on our findings, C.difficile toxins may alter bile acid profiles in the gut by inducing FGF-19 production,” said Tessier. “Further studies need to be done to determine if this hormone is a true marker of C.diff infection.”
Tessier’s study also examined the bile acid profiles of four patients who received liver transplants. High levels of taurocholate were found in their stool, which increased their risk of C.diff infection.