Breath tests can lead to more personalized therapies for IBS patients

A new study led by Cedars-Sinai investigators found using breath tests to identify gut gas profiles can potentially help lead to more personalized therapies for people diagnosed with irritable bowel syndrome (IBS). The most common gastrointestinal disorder affects 10% to15% of the world's population.

The disease spectrum for IBS includes subtypes that are diarrhea-predominant (IBS-D) or constipation-predominant (IBS-C). Cedars-Sinai scientists have now linked specific gas producing microbial patterns in the intestinal tract to the different IBS subtypes.

In the study, published in the American Journal of Gastroenterology, investigators examined data from two randomized controlled clinical trials and found distinctive microbial signatures associated with the two IBS subtypes.

"We found a clear relationship between breath test results and the gut microbiome, with each being a predictor of IBS phenotypes," said Mark Pimentel, MD, executive director of the Medically Associated Science and Technology (MAST) Program at Cedars-Sinai and senior author of the study.

"Using breath tests to identify gut gas profiles, as well as stool analysis, we found that IBS-C patients, who presented more often with constipation, had higher levels of methane and methane-producing organisms in their gut. In contrast, IBS-D subjects, for whom diarrhea is common, showed elevated breath levels of hydrogen and hydrogen sulfide as well as a higher relative abundance of hydrogen sulfide-producing bacteria in their gut microbiome," said Pimentel, who is also a professor of Medicine showed elevated breath levels of hydrogen and hydrogen sulfide

Investigators were able to identify links between the presence of specific organisms in the gut and disease expression. Methanobrevibacter smithii appeared to be the primary methane-producing microorganism in IBS-C. The hydrogen sulfide-generating bacteria in IBS-D were Fusobacterium and Desulfovibrio.

Although the underlying mechanism of irritable bowel syndrome has been poorly understood, we continue to find that the gut microbiome plays a key role. In our study, IBS-C subjects with the distinct breath methane gas profile had greater diversity of microbes in the intestinal tract. By contrast, lower microbial diversity was found in IBS-D subjects with higher breath hydrogen sulfide."

Maria Jesus Villanueva-Millan, PhD, project scientist in the Medically Associated Science and Technology (MAST) Program and lead author of the study

Measuring hydrogen, methane and hydrogen sulfide via noninvasive breath testing is essential to fully understanding IBS and to developing effective treatments, Villanueva Millan added.

"Knowing the microtypes in this much detail is already leading to custom therapies for IBS-C and IBS-D. This precision medicine approach will include new pharmacologics, including the use of antibiotics, as well as the development of novel diet strategies for each disease subtype," said Pimentel.