Fungus May Be 'Key Factor' in Crohn's Disease

Peter Russell

September 29, 2016

A fungus in the gut could be a key factor in the development of Crohn's disease, according to an investigation by an international team of researchers.

Crohn's is an inflammatory disease of the digestive system which causes a range of debilitating symptoms including abdominal pain, diarrhoea and weight loss. It is thought at least 115,000 people in the UK have Crohn's.

The study, published in the journal mBio, assessed the bacteria and fungi of people with Crohn's disease and compared this to their first degree relatives in 9 families in northern France and Belgium. These results were further compared with individuals from 4 families in the same geographic area who did not have Crohn's.

Bacteria and Fungi 'Work Together'

The researchers found that individuals with Crohn's were more likely to have 2 types of bacteria – E.coli and Serratia marcescens – and 1 fungus (Candida tropicalis) than those without the disease. They say that the presence of all three in a family member was significantly higher compared to their healthy relatives, suggesting that the bacteria and fungus interact in the intestines.

Test-tube research also found that both bacteria and the fungus work together to create a biofilm which sticks to part of the intestines causing inflammation that produces Crohn's disease symptoms.

The scientists, led by a team from Case Western Reserve University School of Medicine in Ohio in the US say this is the first time that any fungus has been linked to Crohn's in humans. Also, it is the first time that a study has implicated Serratia marcescens in potentially contributing to symptoms of the disease.

Professor Mahmoud Ghannoum, who led the study, says in a statement: "Among hundreds of bacterial and fungal species inhabiting the intestines, it is telling that the three we identified were so highly correlated in Crohn’s patients.

"Furthermore, we found strong similarities in what may be called the ‘gut profiles’ of the Crohn’s-affected families, which were strikingly different from the Crohn’s-free families.

"We have to be careful, though, and not solely attribute Crohn’s disease to the bacterial and fungal makeups of our intestines. For example, we know that family members also share diet and environment to significant degrees. Further research is needed to be even more specific in identifying precipitators and contributors of Crohn’s."

'Interesting Area for Further Research'

Commenting on the study in a statement, Dr Wendy Edwards, research manager at Crohn's and Colitis UK, says: "We welcome the findings of this research which gives further evidence as to the role that fungi may play in the cause of Crohn's disease.

"Although the sample size of patients within this study is small, it has highlighted a potentially interesting area for further research.

"Crohn's and Colitis UK are also currently funding work in this important area in order to further advance our worldwide understanding of bacteria and fungi and the role they play in Crohn's disease."


Bacteriome and Mycobiome Interactions Underscore Microbial Dysbiosis in Familial Crohn’s Disease, G Hoarau et al, mBio

Press release, Case Western Reserve University

Crohn's and Colitis UK