title: Investigation of Volatile Organic Compounds Emitted from Faeces for the Diagnosis of Giardiasis.
abstract: BACKGROUND
  Giardiasis is a common intestinal infection caused by the flagellated intestinal protozoan Giardia duodenalis. Several methods are available for the laboratory diagnosis of Giardia, ranging from the microscopic identification of the parasite trophozoite and cyst stages, to immunodiagnosis and PCR. Giardia has unique metabolic pathways resulting from its lack of mitochondria, making it an ideal target for volatile organic compound (VOC) profiling.
  
  
  OBJECTIVE
  To characterise the VOC profile of stool infected with Giardia to detect differences from those found in samples of diarrhoea without Giardia or other infections.
  
  
  METHODS
  Stool was obtained from patients with confirmed Giardia infection and controls with diarrhoea but no identifiable infection. Faecal headspace gas extraction and gas chromatography-mass spectrometry were used to extract and identify VOCs.
  
  
  RESULTS
  More than 100 VOCs were identified when control and Giardia groups were combined, of which 24 showed significant differences between the two groups (p<0.05). Three VOCs had a significantly greater prevalence amongst Giardia cases (p<0.0001) and 9 VOCs showed a significant difference in terms of abundance (p<0.05). AUROC analysis demonstrated a value of 0.902.
  
  
  CONCLUSIONS
  There is a significant difference in the VOC profile of stool from subjects infected with Giardia spp, when compared with non-infected controls. These findings can be explained by the unique metabolism of Giardia.
authors.affiliation: Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool;UK.
authors.forename: Ashley
authors.initials: A
authors.lastname: Bond
authors.affiliation: Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool;UK.
authors.forename: April
authors.initials: A
authors.lastname: Vernon
authors.affiliation: Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool;UK.
authors.forename: Sophie
authors.initials: S
authors.lastname: Reade
authors.affiliation: Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool;UK.
authors.forename: Arno
authors.initials: A
authors.lastname: Mayor
authors.affiliation: Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool;UK.
authors.forename: Corrado
authors.initials: C
authors.lastname: Minetti
authors.affiliation: Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool;UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wastling
authors.affiliation: Cumbria and Lancashire Public Health England Centre, Public Health England, York House, Chorley, UK.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Lamden
authors.affiliation: Department of Gastroenterology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK. Chris.Probert@liverpool.ac.uk.
authors.forename: Chris
authors.initials: C
authors.lastname: Probert
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D004739:England; D005243:Feces / Q000737:chemistry* / Q000469:parasitology; D008401:Gas Chromatography-Mass Spectrometry; D016829:Giardia lamblia / Q000378:metabolism*; D005873:Giardiasis / Q000175:diagnosis* / Q000378:metabolism / Q000469:parasitology; D006801:Humans; D011237:Predictive Value of Tests; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D055549:Volatile Organic Compounds