Microbial Signature Could Help in Crohn’s Diagnosis

By Anne Harding

February 23, 2017

NEW YORK (Reuters Health) – Crohn’s disease (CD) and ulcerative colitis (UC) are distinctly different on the microbiome level, new findings show.

“Dysbiosis (alteration in the microbiome) appears to be greater in Crohn’s disease than in ulcerative colitis, involving more groups of microbes,” Dr. Chaysavanh Manichanh of Vall d’Hebron Research Institute in Barcelona, one of the study’s authors, told Reuters Health by email.

“The microbiomarkers identified in this work will facilitate the discrimination between CD and UC and may decrease the systematic use of endoscopy for the diagnostic of this disease or help confirming its diagnosis,” Dr. Manichanh added.

Clinicians often have a difficult time distinguishing between UC and CD, Dr. Manichanh and colleagues note in their report, published online February 7 in Gut.

While studies clearly show alterations in the microbiome of IBD patients compared to healthy controls, they add, differences between patients with CD and UC have not been investigated.

The researchers analyzed 2,045 fecal samples from patients with and without IBD from Spain, Belgium, the UK and Germany.

Patients with CD had less microbial diversity and a more unstable microbial community than the UC patients. Smokers also showed microbiome differences compared to non-smokers within each type of IBD, while there were also microbial differences based on disease localization in both CD and UC.

Eight bacterial genera showed potential to discriminate between healthy controls and patients with CD and UC: Faecalibacterium, Peptostreptococcaceae, Anaerostipes, Christensenellaceae, Fusobacterium, Escherichia, Collinsella and Methanobrevibacter.

“Faecalibacterium, an unknown genus of Peptostreptococcaceae, Anaerostipes, Methanobrevibacter and an unknown genus of Christensenellaceae were abundant in healthy controls and UC and absent or almost absent in CD ones, while Fusobacterium and Escherichia were abundant in patients with CD and almost absent in healthy controls and UC,” the researchers found. “Collinsella, which was found mostly in UC cases, allowed us to discriminate between UC and CD.”

The signature had an overall sensitivity of 80% and a specificity of 94% for detecting CD versus healthy controls. Specificity was 94% for distinguishing CD from anorexia, 89% for distinguishing CD from irritable bowel syndrome (IBS), and 91% for distinguishing CD from UC.

“The findings may help designing future treatments based on the use of microorganisms, either by fecal microbiota transplantation (FMT) through an appropriate selection of the donor sample or by transplanting directly the missing microorganisms in CD patients,” Dr. Manichanh said. “Indeed, the donor sample may contain the six missing microorganisms identified in CD patients and may not contain the two groups of microbes associated with CD patients.”

Currently, the researcher added, FMT is not effective in CD or UC, helping fewer than 40% of patients, compared to 95% of patients with Clostridium difficile infection.

“The next steps of this research is to validate those microbiomarkers in all types of CD patients” – including recently diagnosed CD patients with inflammation only in the colon, to be able to different them from UC patients.

SOURCE: http://bit.ly/2m5fZAy

Gut 2017.