title: Quantification of Helicobacter pylori in gastric mucosa by real-time polymerase chain reaction: comparison with traditional diagnostic methods.
abstract: The aim of this study was to determine the main diagnostic validity parameters of a quantitative real-time polymerase chain reaction (PCR) system for detecting Helicobacter pylori in gastric biopsies. Prospective study. The real-time PCR has an internal control for eliminating the false negatives. Our system has a good diagnostic capacity compared with the gold standard and was superior in antral mucosa: area under the curve was 0.91 for antrum (95% confidence interval [CI] 0.87 to 0.96) and 0.83 for corpus (95% CI 0.77 to 0.9). The optimum cut-off point was 3.56 microorganisms/cell for antrum (sensitivity 83.5% [95% CI 74.2 to 89.9]; specificity 91.3% [95% CI 82.3 to 96.0]; positive predictive value 92.2%; negative predictive value 81.8%). The positive likelihood ratios were 9.61 and 8.52 for antrum and corpus, respectively. With the cut-off point that maximises the Youden index, 8.7% false positives were obtained. Our methodology is useful for diagnosing infection due to H. pylori and the false positives detected probably correspond to patients who were actually infected but the infection was not detected by traditional techniques. The clinical importance of these cases should be studied in greater detail since they may involve colonisations unrelated to the patient's digestive pathology.
authors.affiliation: S. Microbiología, Hospital General Universitario de Elche, Elche (Alicante), Spain.
authors.forename: Sofía
authors.initials: S
authors.lastname: Belda
authors.forename: Jesús
authors.initials: J
authors.lastname: Saez
authors.forename: Miguel
authors.initials: M
authors.lastname: Santibáñez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Rodríguez
authors.forename: Antonio
authors.initials: A
authors.lastname: Galiana
authors.forename: Javier
authors.initials: J
authors.lastname: Sola-Vera
authors.forename: Montserrat
authors.initials: M
authors.lastname: Ruiz-García
authors.forename: Alicia
authors.initials: A
authors.lastname: Brotons
authors.forename: Elena
authors.initials: E
authors.lastname: López-Girona
authors.forename: Eva
authors.initials: E
authors.lastname: Girona
authors.forename: Carlos
authors.initials: C
authors.lastname: Sillero
authors.forename: Gloria
authors.initials: G
authors.lastname: Royo
mesh_terms: D058491:Bacterial Load / Q000379:methods*; D001706:Biopsy; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology*; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity