title: Detection of Helicobacter pylori by Real-Time PCR for 16s rRNA in Stools of NonInfected Healthy Children, Using ELISA Antigen Stool Test as the Gold Standard.
abstract: BACKGROUND
  We previously detected Helicobacter pylori infection by stool antigen ELISA assay in 33-41% of asymptomatic Chilean children between 2-3 years of age, of which 11-20% had a transient infection and 21-22% a persistent infection. A total of 88% of ELISA-positive samples were also rtPCR positive, while 37/133 (33%) of ELISA-negative stool samples were rtPCR positive. The significance of a ELISA-negative/rtPCR-positive sample requires clarification. We aimed to determine whether rtPCR is able to detect persistent infections not detected by ELISA.
  
  
  METHODS
  We selected 36 children with an ELISA-negative/rtPCR-positive stool sample, of which 25 were never H. pylori infected according to ELISA, and 11 had a transient infection with an ELISA-positive sample before or after the discordant sample. At least two additional consecutive ELISA-negative samples per child were tested in duplicate by rtPCR for the 16s rRNA gene.
  
  
  RESULTS
  A total of 14 of 78 (17.9%) rtPCR reactions were positive, but only 4/78 (5.1%) were positive in both duplicates, representing a total of 3/36 (8.3%) children with an additional rtPCR-positive sample, only one of whom was persistently negative by ELISA. One child with a transient infection had two positive rtPCR reactions despite negative ELISA samples.
  
  
  CONCLUSIONS
  In H. pylori noninfected or transiently infected children, as determined by stool ELISA, additional ELISA-negative/rtPCR-positive stool samples were found in 8.3% of children, but a possible persistent infection was only identified in 2.7% of children. Thus, the characterization of infection dynamics in children is not being misrepresented by application of stool ELISA. Furthermore, rtPCR does not significantly improve dynamic characterization.
authors.affiliation: Microbiology and Mycology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Sergio
authors.initials: S
authors.lastname: George
authors.affiliation: Microbiology and Mycology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Nora
authors.initials: N
authors.lastname: Mamani
authors.affiliation: Department of Pediatrics and Pediatric Surgery (Eastern Campus), Faculty of Medicine, Luis Calvo Mackenna Hospital, Universidad de Chile, Santiago, Chile.
authors.forename: Yalda
authors.initials: Y
authors.lastname: Lucero
authors.affiliation: Department of Pediatrics and Pediatric Surgery (Eastern Campus), Faculty of Medicine, Luis Calvo Mackenna Hospital, Universidad de Chile, Santiago, Chile.
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Torres
authors.affiliation: Department of Pediatrics and Pediatric Surgery (Eastern Campus), Faculty of Medicine, Luis Calvo Mackenna Hospital, Universidad de Chile, Santiago, Chile.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Farfán
authors.affiliation: Microbiology and Mycology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Lagomarcino
authors.affiliation: Microbiology and Mycology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Andrea
authors.initials: A
authors.lastname: Orellana
authors.affiliation: Microbiology and Mycology Program, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Santiago, Chile.
authors.forename: Miguel
authors.initials: M
authors.lastname: O'Ryan
mesh_terms: D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005243:Feces / Q000382:microbiology*; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011446:Prospective Studies; D012329:RNA, Bacterial / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*
chemical_list: D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S
keywords: 
  Helicobacter pylori
  ; childhood infection; stool PCR; stool antigen detection