title: Real-time PCR improves Helicobacter pylori detection in patients with peptic ulcer bleeding.
abstract: OBJECTIVE
  Histological and rapid urease tests to detect H. pylori in biopsy specimens obtained during peptic ulcer bleeding episodes (PUB) often produce false-negative results. We aimed to examine whether immunohistochemistry and real-time PCR can improve the sensitivity of these biopsies.
  
  
  METHODS
  We selected 52 histology-negative formalin-fixed paraffin-embedded biopsy specimens obtained during PUB episodes. Additional tests showed 10 were true negatives and 42 were false negatives. We also selected 17 histology-positive biopsy specimens obtained during PUB to use as controls. We performed immunohistochemistry staining and real-time PCR for 16S rRNA, ureA, and 23S rRNA for H. pylori genes on all specimens.
  
  
  RESULTS
  All controls were positive for H. pylori on all PCR assays and immunohistochemical staining. Regarding the 52 initially negative biopsies, all PCR tests were significantly more sensitive than immunohistochemical staining (p<0.01). Sensitivity and specificity were 55% and 80% for 16S rRNA PCR, 43% and 90% for ureA PCR, 41% and 80% for 23S rRNA PCR, and 7% and 100% for immunohistochemical staining, respectively. Combined analysis of PCR assays for two genes were significantly more sensitive than ureA or 23S rRNA PCR tests alone (p<0.05) and marginally better than 16S rRNA PCR alone. The best combination was 16S rRNA+ureA, with a sensitivity of 64% and a specificity of 80%.
  
  
  CONCLUSIONS
  Real-time PCR improves the detection of H. pylori infection in histology-negative formalin-fixed paraffin-embedded biopsy samples obtained during PUB episodes. The low reported prevalence of H. pylori in PUB may be due to the failure of conventional tests to detect infection.
authors.affiliation: Digestive Diseases Department, Hospital de Sabadell, Institut Universitari Parc Taulí, Universitat Autònoma de Barcelona, Sabadell, Spain.
authors.forename: María José
authors.initials: MJ
authors.lastname: Ramírez-Lázaro
authors.forename: Sergio
authors.initials: S
authors.lastname: Lario
authors.forename: Alex
authors.initials: A
authors.lastname: Casalots
authors.forename: Esther
authors.initials: E
authors.lastname: Sanfeliu
authors.forename: Loreto
authors.initials: L
authors.lastname: Boix
authors.forename: Pilar
authors.initials: P
authors.lastname: García-Iglesias
authors.forename: Jordi
authors.initials: J
authors.lastname: Sánchez-Delgado
authors.forename: Antònia
authors.initials: A
authors.lastname: Montserrat
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Bella-Cueto
authors.forename: Marta
authors.initials: M
authors.lastname: Gallach
authors.forename: Isabel
authors.initials: I
authors.lastname: Sanfeliu
authors.forename: Ferran
authors.initials: F
authors.lastname: Segura
authors.forename: Xavier
authors.initials: X
authors.lastname: Calvet
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D001706:Biopsy; D017931:DNA Primers; D005798:Genes, Bacterial; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification*; D006470:Hemorrhage / Q000150:complications / Q000382:microbiology*; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D010437:Peptic Ulcer / Q000150:complications / Q000382:microbiology* / Q000473:pathology; D016133:Polymerase Chain Reaction / Q000379:methods*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D012336:RNA, Ribosomal, 16S