title: IgG antibodies against microorganisms and atopic disease in Danish adults: the Copenhagen Allergy Study.
abstract: BACKGROUND
  Seropositivity to food-borne and orofecal microorganisms (hepatitis A virus, Helicobacter pylori, and Toxoplasma gondii ), which are considered to be markers of poor hygiene, has been reported to be associated with a lower prevalence of atopy. In contrast, colonization of the gut with Clostridium difficile, a potential intestinal bacterial pathogen, in early childhood may be associated with a higher prevalence of atopy.
  
  
  OBJECTIVE
  The objective of this study was to investigate the association between atopy and exposure to 2 groups of food-borne and orofecal microorganisms: (1) markers of a poor hygiene and (2) intestinal bacterial pathogens.
  
  
  METHODS
  A cross-sectional population-based study of 15- to 69-year-olds living in Copenhagen, Denmark, was carried out in 1990 to 1991. Atopy was defined as a positive test result for specific IgE to at least 1 of 6 inhalant allergens. Exposure to microorganisms was assessed as IgG seropositivity to microorganisms.
  
  
  RESULTS
  Seropositivity to 2 or 3 markers of poor hygiene (hepatitis A virus, H pylori, and T gondii ) was associated with a lower prevalence of atopy (adjusted odds ratio, 0.5; 95% CI, 0.3 to 0.8). In contrast, seropositivity to 2 or 3 intestinal bacterial pathogens (C difficile, Campylobacter jejuni, and Yersinia enterocolitica ) was associated with a higher prevalence of atopy (adjusted odds ratio, 1.7; 95% CI, 1.2 to 2.6).
  
  
  CONCLUSIONS
  Exposure to markers of poor hygiene was associated with a lower prevalence of atopy, whereas exposure to intestinal bacterial pathogens was associated with a higher prevalence of atopy. These findings raise the hypothesis that different groups of food-borne and orofecal microorganisms may have different effects on the risk of atopy.
authors.affiliation: Centre for Preventive Medicine, Glostrup University Hospital, Denmark.
authors.forename: Allan
authors.initials: A
authors.lastname: Linneberg
authors.forename: Christian
authors.initials: C
authors.lastname: Ostergaard
authors.forename: Michael
authors.initials: M
authors.lastname: Tvede
authors.forename: Leif Pervical
authors.initials: LP
authors.lastname: Andersen
authors.forename: Niels Henrik
authors.initials: NH
authors.lastname: Nielsen
authors.forename: Flemming
authors.initials: F
authors.lastname: Madsen
authors.forename: Lars
authors.initials: L
authors.lastname: Frølund
authors.forename: Asger
authors.initials: A
authors.lastname: Dirksen
authors.forename: Torben
authors.initials: T
authors.lastname: Jørgensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000913:Antibodies, Protozoan / Q000097:blood; D003430:Cross-Sectional Studies; D016480:Helicobacter pylori / Q000276:immunology; D035922:Hepatitis A Antibodies / Q000097:blood; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D007074:Immunoglobulin G / Q000097:blood*; D008875:Middle Aged; D014122:Toxoplasma / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000913:Antibodies, Protozoan; D035922:Hepatitis A Antibodies; D007074:Immunoglobulin G