title: The accuracy of serologic diagnosis of Helicobacter pylori infection in school-aged children of mixed ethnicity.
abstract: The present study evaluated two non-invasive diagnostic methods for H. pylori infection in children, i.e. an in-house ELISA using sonicated Campylobacter jejuni antigen for absorption of cross-reacting antibodies and an immunoblot kit (Helico Blot 2.0, Genelabs, Singapore). 13C -Urea breath test (13C-UBT) was used as reference
  
  
  METHODS
  Sera and questionnaires were collected from 695/858 (81%) Swedish school children with mixed ethnic backgrounds within a cross-sectional, community-based study. Of 133 children with an ELISA OD value of > or = 0.1, all were screened with immunoblot and 107 made a 13C-UBT. The negative controls were 34/37 children from three school classes with an ELISA OD value of < 0.1 and volunteering for a 13C-UBT. An adjusted cut-off level for the ELISA of OD value 0.22 resulted in a sensitivity of 97.8%, a specificity of 95.8% and a concordance index of 97.2%. The Helico Blot 2.0 had a sensitivity of 97.8%, a specificity of 93.8% and a concordance index of 96.5%. The best concordance was seen for the 26.5 kDa (98.6%), 30 kDa (95.7%) and 19.5 kDa (91.5%) antigens. The corresponding concordance index for CagA was 78%, for VacA 73.8% and for the 35kDa antigen 68.8%. A significant difference in the distribution of the 19.5 and 26.5 kDa bands but not of CagA/VacA was noted by ethnic background. With an adjusted cut-off level for the enzyme-linked immunosorbent assay (ELISA), both non-invasive methods were found to have an adequate performance in a pediatric population. The differences in antibody response patterns by ethnic background represent a caveat in the interpretation of serological studies.
authors.affiliation: Sachs' Department of Pediatrics, Södersjukhuset, Karolinska Institutet, Stockholm, Sweden. Ylva.Tindberg@mep.ki.se
authors.forename: Y
authors.initials: Y
authors.lastname: Tindberg
authors.forename: C
authors.initials: C
authors.lastname: Bengtsson
authors.forename: M
authors.initials: M
authors.lastname: Bergström
authors.forename: M
authors.initials: M
authors.lastname: Granström
mesh_terms: D000293:Adolescent; D000942:Antigens, Bacterial / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism; D001944:Breath Tests; D002648:Child; D004797:Enzyme-Linked Immunosorbent Assay; D005069:Evaluation Studies as Topic; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000208:ethnology; D016480:Helicobacter pylori / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008297:Male; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods; D013548:Sweden / Q000453:epidemiology; D014508:Urea / Q000032:analysis
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D014508:Urea