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Title: An investigation of volatile compounds from faeces in humans and chickens to determine their potential in specific gastrointestinal disease diagnoses
Author: Garner, Catherine Elizabeth.
Awarding Body: University of the West of England, Bristol,
Current Institution: University of the West of England, Bristol
Date of Award: 2007
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Abstract:
Little is known about the volatile organic compounds (VOCs) in faeces and their potential health consequences. Patients and healthcare professionals have observed that faeces often smell abnormal during gastrointestinal disease. The aim of this work was to define the volatiles emitted from the faeces of healthy asymptomatic donors and of patients with gastrointestinal disease, Campylobacter, Clostridium difficle, ulcerative colitus and a small number of Bangladesh samples with Cholera and Rotavirus. The hypotheses were that i) Some VOCs would be shared in health, ii) VOCs would be constant in individuals, and iii) specific changes in VOCs would occur in disease. Volatile emissions in asymptomatic faeces were defined in a cohort and a longitudinal study. A method was designed to extract the faecal V OCs using solid phase n1icro-extraction and analyzed by· gas chromatography / mass spectrometry. In the cohort study (30 subjects), 297 volatiles were identified, in all samples ethanoic, butanoic, pentanoic acids, benzaldehyde, ethanal, carbon disulfide, dimethyldisulfide, acetone, 2-butanone, 2,3 butanedione, 6-methyl-5-hepten-2-one, indole and 4-methylphenol were found. Forty four compounds were shared by 80% of subjects. In the longitudinal study (10 subjects, 5 samples each), 292 volatiles were identified; there was some inter and intra subject variations in VOC concentrations with time. When compared to healthy donors, volatile patterns from faeces of patients with ulcerative colitis (18), Clostridium difficile (22) and Campylobacter jejuni (31), were significantly different. Application of discriminant functions on the sample data gives 100% predictive accuracy and 96% predictive accuracy when cross-classifying using the leave-one-out procedure. Patterns for the Bangladesh samples were seen particularly in the Total Ion Chromatographs of the various disease. Campylobacter in humans is generally caused by contamination of chickens from farms, therefore the VOCs from chicken feces in both Campylobacter infected farms and non-infected farms and cultures of the Campylobacters isolated were analysed. 71 broiler chicken fecal samples were studied; from farm A, 31 samples were obtained, none contained Campylobacter; from farm B, 20 samples were obtained, all were contaminated; from farm C, 20 samples were obtained, 10 with and 10 without Campylobacter. Analysis of the profile of VOCs revealed that each farm had a unique profile. Once the farmspecific VOCs were excluded, a Campylobacter-specific profile was identified. The model, based on 6 compounds, reliably identified the presence or absence of Campylobacter in >95% of birds. The identification of umque odour patterns associated with Campylobacter infections will enable the production of a rapid tool for identification of chickens that carry Campylobacter. This could underpin novel methods of biosecurity and reduce the risk of transmission to humans. This thesis intends to underpin the hypothesis that bacteria and virus from faeces carries a unique pattern of volatiles that could be utilised in to facilitate a quick and accurate diagnosis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.444524  DOI: Not available
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