People with irritable bowel syndrome have a very different gut flora. This conclusion provides more insight into the cause of this common ailment.
It isn't a case of some other bacteria being present in an irritated gut, but that changes occur in the ratios between bacteria groups. For instance, the researchers found relatively large numbers of Firmicutes while the number of Bacteroidetes had gone down considerably. 'These changes are related to the disease and the acuteness of the symptoms,' explains PhD student Sebastian Tims. You don't see any major culprit; it's more like a fingerprint. Tims: 'You get subtle differences across several groups and these are clearly related to the disease.'
Tims and his supervisor Marjana Rajlic-Stojanovic examined the gut floras of 62 people with irritable bowel syndrome and 46 healthy control subjects during the experiment. They took samples of faeces and cultivated the bacteria DNA in them. Subsequently, they placed these on a chip which identified known intestinal bacteria DNA. The patients also noted symptoms in a diary which the researchers used to compare the acuteness of the disease with the specific symptoms.
Pieces of the puzzle
With these results, an objective test for the disease seems to be in sight. Diagnoses are now being made with the so-called 'Rome-II criteria', where symptoms have to persist for at least six months.
The study enables more pieces of the puzzle to fall into place. 'This doesn't mean that we can explain everything,' says Professor Willem de Vos of Microbiology. 'But we feel that we are heading in the right direction.' Like when the researchers suspect that some of these changes can explain the symptoms. For example, intestinal pain can be caused by proteins released by overabundant Firmicutes. A bloated feeling and flatulency result when there are less methane-producing bacteria to break down hydrogen gas.
De Vos is also pleased that this extensive study confirms the results from smaller experiments. The next step, he says, is to follow the progress of the disease. In a major trial carried out together with Ellen Kampman, professor of Nutrition and Cancer at the Gelderse Vallei Hospital, the group is monitoring about 100 patients for changes in the long term. De Vos: 'We only have a single frame at present, and we are keen to see the entire film.'