An Investigation of Fecal Volatile Organic Metabolites in Irritable Bowel Syndrome

Abstract

Diagnosing irritable bowel syndrome (IBS) can be a challenge; many clinicians resort to invasive investigations in order to rule out other diseases and reassure their patients. Volatile organic metabolites (VOMs) are emitted from feces; understanding changes in the patterns of these VOMs could aid our understanding of the etiology of the disease and the development of biomarkers, which can assist in the diagnosis of IBS. We report the first comprehensive study of the fecal VOMs patterns in patients with diarrhea-predominant IBS (IBS-D), active Crohn's disease (CD), ulcerative colitis (UC) and healthy controls. 30 patients with IBS-D, 62 with CD, 48 with UC and 109 healthy controls were studied. Diagnosis of IBS-D was made using the Manning criteria and all patients with CD and UC met endoscopic, histologic and/or radiologic criteria. Fecal VOMs were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). 240 VOMs were identified. Univariate analysis showed that esters of short chain fatty acids, cyclohexanecarboxylic acid and its ester derivatives were associated with IBS-D (p<0.05), while aldehydes were more abundant in IBD (p<0.05). A predictive model, developed by multivariate analysis, separated IBS-D from active CD, UC and healthy controls with a sensitivity of 94%, 96% and 90%; and a specificity of 82%, 80% and 80% respectively (p<0.05). The understanding of the derivation of these VOMs may cast light on the etiology of IBS-D and IBD. These data show that fecal VOMs analyses could contribute to the diagnosis of IBS-D, for which there is no laboratory test, as well as IBD.

Application of Fecal Volatile Organic Compound Analysis in Clinical Practice: Current State and Future Perspectives

“…They demonstrated significant differences between active CD vs. IBS and IBS vs. HC (Table 3). Both the sensitivity and specificity for the discrimination of IBS from HC and IBS from IBD are in line with a previous conducted study by Ahmed et al [33].…”

“…In 2013, Ahmed et al compared fecal VOCs of 30 diarrhea-predominant adult IBS patients to 110 adult IBD patients by means of GC-MS [33]. They found that three types of VOCs were more abundant in the IBS group, while the abundance of five types of VOCs were higher in the IBD group (Table 3).…”

Enhancing Diagnostic Performance of Symptom-Based Criteria for Irritable Bowel Syndrome by Additional History and Limited Diagnostic Evaluation

“…[15][16][17][18][19] Some of the proposed biomarkers (which are unfortunately not widely available) may also serve as therapeutic targets and enhance outcomes. Despite this, a systematic review and meta-analysis that evaluated all generally available approaches to diagnose IBS demonstrated that biomarkers alone performed similarly to symptom-based criteria, 20 while adding to the cost of care.…”

Recent Applications of Electronic-Nose Technologies for the Noninvasive Early Diagnosis of Gastrointestinal Diseases

“…The many types and quantities of headspace VOCs released from fecal samples reflect the overall metabolic state of an individual which may be affected by a wide variety of factors that alter intestinal metabolism including diet, medication and drug use, ingestion of probiotics and antibiotics, as well as types of gastrointestinal resident microbes (GIRMs) present which comprise the GI-microbiome, and presence of disease states in the body [8,9]. Consequently, alterations in metabolism caused by GI-tract infections, inflammation, and related disease states can result in significant changes in GIRMcomposition, altering the complex mixture of VOCs gases released in fecal samples.…”

“…For GI diseases, analysis of VOCs emitted from fecal samples have shown significant changes in VOC profiles that have helped in disease etiology and identification of disease biomarkers associated with specific diseases [8]. Changes in VOC profiles of the GI-tract, resulting from alterations in host physiology due to disease processes (pathogenesis), also often cause changes in gut microbiota composition due to changes in GI-growth conditions for microbes in diseased patients compared with healthy controls.…”