3-Hydroxy fatty acids in faeces of patients with Crohn's disease or ulcerative colitis as a non-invasive diagnostic approach

The microbiota is part of the gastrointestinal ecosystem. A more detailed understanding should provide insight into multiple human disease states. This study investigated inflammatory bowel disease (Crohn's disease and ulcerative colitis). Previous analyses have suggested a role of gram-negative bacteria including Escherichia coli. An integrated procedure is presented where gas chromatography-mass spectrometry is used to determine chemical markers of gram-negative bacterial lipopolysaccharide (3-hydroxy fatty acids with 10-18 carbon atoms) in faecal samples. Six patients with Crohn's disease (CD), five with ulcerative colitis (UC) and six healthy adults were chosen as groups of interest. Nine saturated straight-chain 3-OH fatty acids of 10-18 carbon chain lengths and six iso- and anteiso-branched-chain 3-OH fatty acids of 15-18 carbon chain lengths were detected. Significant differences were found in the 3-OH n-C17:0, 3-OH i-C18:0 and 3-OH n-C18:0 composition of faeces. The present study therefore confirms that alteration of the composition of the endogenous gram-negative microbiota may be of importance in inflammatory bowel disease and those alterations could be detected with a non-invasive chemical-analytical approach.