title: Oral and gastric Helicobacter pylori: effects and associations.
abstract: BACKGROUND
  This study consisted in the comparison of the prevalence of Helicobacter pylori (H. pylori) present in the stomach and in saliva of a sample of Portuguese adolescents and the assessment of the association between H. pylori infection with socio-demographic variables and prevalence of dental caries.
  
  
  METHODS
  A cross-sectional study was designed including a sample of 447 adolescents aged 12 to 19 years old, attending a public school in Sátão, Portugal. A questionnaire about socio-demographic variables and oral health behaviors was applied. Gastric H. pylori infection was determined using the urease breath test (UBT). Saliva collection was obtained and DNA was extracted by Polymerase Chain Reaction (PCR) in order to detect the presence of oral H. pylori.
  
  
  RESULTS
  The prevalence of gastric H. pylori detected by UBT was 35.9%. Within the adolescents with a gastric UBT positive, only 1.9% were positive for oral H. pylori. The presence of gastric H. pylori was found to be associated with age (>15years, Odds ratio (OR)=1.64, 95%CI=1.08-2.52), residence area (urban, OR=1.48, 95%CI=1.03-2.29) and parents´ professional situation (unemployed, OR=1.22, 95%CI=1.02-1.23). Among those with detected dental caries during the intra-oral observation, 37.4% were positive for gastric H. pylori and 40.2% negative for the same bacterial strain (p=0.3).
  
  
  CONCLUSIONS
  The oral cavity cannot be considered a reservoir for infection of H. pylori. Gastric H. pylori infection was found to be associated with socio-demographic variables such as age, residence area and socioeconomic status.
authors.affiliation: Health Sciences Research Centre, Health Sciences Faculty, Beira Interior University, Covilhã, Portugal; Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal; Chemical Process Engineering and Forest Products Research Centre, Chemical Engineering Department, University of Coimbra, Coimbra, Portugal; Health Sciences Department, Portuguese Catholic University, Viseu, Portugal.
authors.forename: Nélio
authors.initials: N
authors.lastname: Veiga
authors.affiliation: Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Pereira
authors.affiliation: Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors.forename: Carlos
authors.initials: C
authors.lastname: Resende
authors.affiliation: Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal.
authors.forename: Odete
authors.initials: O
authors.lastname: Amaral
authors.affiliation: Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal.
authors.forename: Manuela
authors.initials: M
authors.lastname: Ferreira
authors.affiliation: Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Nelas
authors.affiliation: Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal.
authors.forename: Claudia
authors.initials: C
authors.lastname: Chaves
authors.affiliation: Research Centre for Education, Technology and Health Studies, Polytechnic Institute of Viseu, Viseu, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Duarte
authors.affiliation: Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Cirnes
authors.affiliation: Institute of Molecular Pathology and Immunology of the University of Porto, Porto, Portugal.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Machado
authors.affiliation: Chemical Process Engineering and Forest Products Research Centre, Chemical Engineering Department, University of Coimbra, Coimbra, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Ferreira
authors.affiliation: Health Sciences Research Centre, Health Sciences Faculty, Beira Interior University, Covilhã, Portugal.
authors.forename: Ilídio J
authors.initials: IJ
authors.lastname: Correia
mesh_terms: D000293:Adolescent; D002648:Child; D004269:DNA, Bacterial / Q000302:isolation & purification; D003710:Demography; D005260:Female; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D008297:Male; D009055:Mouth / Q000382:microbiology* / Q000473:pathology; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013270:Stomach / Q000382:microbiology* / Q000473:pathology; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial