Mixed Infections ofHelicobacter pyloriIsolated from Patients with Gastrointestinal Diseases in Taiwan

Abstract

Background. PersistentHelicobacter pyloriinfection may induce several upper gastrointestinal diseases. Two major virulence factors ofH. pylori, vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA), are thought to be associated with the severity of disease progression. The distribution ofvacAandcag-pathogenicity island (cag-PAI) alleles varies inH. pyloriisolated from patients in different geographic regions.Aim. To assess the association between mixed infection ofH. pyloriclinical isolates from Taiwanese patients and the severity of gastrointestinal diseases.Methods. A total of 70 patients were enrolled in this study. Six distinct and well-separated colonies were isolated from each patient and 420 colonies were analyzed to determine the genotypes of virulence genes.Results. The prevalence of mixed infections of allH. pylori-infected patients was 28.6% (20/70). The rate of mixed infections in patients with duodenal ulcer (47.6%) was much higher than that with other gastrointestinal diseases (P<0.05).Conclusions.H. pylorimixed infections show high genetic diversity that may enhance bacterial adaptation to the hostile environment of the stomach and contribute to disease development.