title: Significance of transiently positive enzyme-linked immunosorbent assay results in detection of Helicobacter pylori in stool samples from children.
abstract: In young children, the significance of stool samples transiently positive for Helicobacter pylori antigen is unknown. As part of a larger prospective study on enteric infections, stool samples were obtained from 323 children at two time points 3 months apart and tested for H. pylori antigen using a commercially available enzyme-linked immunosorbent assay (ELISA) test. Seminested PCR for a Helicobacter-specific 16S rRNA gene was performed on all 26 pairs reverting from positive to negative (transient positives), all 4 persistent antigen-positive pairs, and 10 randomly selected persistent antigen-negative pairs. Helicobacter species were amplified from the first stool samples of 15/26 (58%) of the transient positives and 1 (25%) of 4 persistent positives. No Helicobacter species were amplified from the 10 persistent negatives. Among the 15 amplicons from transient-positive stool, H. pylori was sequenced and identified from 12 (80%; 95% confidence interval, 52% to 96%) and other Helicobacter spp. were identified from three (Helicobacter canis, Helicobacter winghamensis, and MIT 99-5504). Four of the 15 remained positive by PCR for the second (antigen-negative) stool sample, including all 3 initially identified as non-H. pylori. Helicobacter bilis was amplified from the second sample of a persistent positive. Two of eight transient positives from whom serum was available had accompanying transient elevations in anti-H. pylori antibodies. Transiently positive stool ELISAs for H. pylori are common and represent H. pylori in the majority of cases where sequences can be obtained. A not-insignificant percentage of antigen-positive stools, however, may represent other Helicobacter species.
authors.affiliation: Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, 300 Pasteur Dr., Stanford, CA 94305-5107, USA. tdhaggerty@stanford.edu
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Haggerty
authors.forename: Sharon
authors.initials: S
authors.lastname: Perry
authors.forename: Luz
authors.initials: L
authors.lastname: Sanchez
authors.forename: Guillermo
authors.initials: G
authors.lastname: Perez-Perez
authors.forename: Julie
authors.initials: J
authors.lastname: Parsonnet
mesh_terms: D000942:Antigens, Bacterial / Q000032:analysis; D002648:Child; D015331:Cohort Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005243:Feces / Q000737:chemistry / Q000382:microbiology*; D016481:Helicobacter Infections / Q000175:diagnosis*; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods; D015203:Reproducibility of Results
chemical_list: D000942:Antigens, Bacterial