摘要：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 1018 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-C<em>17:0</em>, 3-OH i-C<em>18:0</em> and 3-OH n-C<sup>18:0</em> composition of faeces. The present study therefore confirms that alteration of the composition of the endogenous gramnegative microbiota may be of importance in inflammatory bowel disease and those alterations could be detected with a non-invasive chemical-analytical approach.Key words: faecal microbiota, gas chromatography-mass spectrometry, inflammatory bowel diseases
