• Good bug might not be good after all in Crohn’s disease

    This part-CICRA funded study looked at overall bacterial diversity in biopsies from the colon of 11 children with Crohn’s disease, 11 with ulcerative colitis (UC) and 12 who had a normal colon and no evidence of IBD. The study used a method called next-generation sequencing to identify the top 11,000 bacteria present in each patient using DNA-based “barcodes”. Importantly, this study looked only at children who were newly diagnosed with IBD and who had not been started on any treatments, reducing the likelihood of any “chicken and egg” questions about whether treatments or length of disease may have influenced the bacteria living in the gut.

    The results challenge some established ideas from previous adult studies, firstly that the overall variety (diversity) of bacteria are reduced in UC compared to normal – this was not the case here but was true in Crohn’s disease; secondly that Faecalibacterium prausnitzii is a bacterial species that is beneficial and is reduced in Crohn’s disease – in fact it was increased in Crohn’s here; and finally, that broad bacterial differences are important in the inflammation of IBD compared to normal – again this was shown not to be the case with no major changes between bacteria at “phylum” level, perhaps the simplest difference between bacterial species.

    The F. prausnitzii finding in particular is important as this bacterium has widely been accepted as one of the “good guys” in Crohn’s disease, having previously been noted to be reduced in those who have recurrence of disease after surgery. The finding of increased levels in children with Crohn’s at first diagnosis mean we may have to think again about this bacterium.

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