Mixed Infections of Isolated from Patients with Gastrointestinal Diseases in Taiwan.

. Persistent infection may induce several upper gastrointestinal diseases. Two major virulence factors of , vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA), are thought to be associated with the severity of disease progression. The distribution of and -pathogenicity island (-PAI) alleles varies in isolated from patients in different geographic regions. . To assess the association between mixed infection of clinical isolates from Taiwanese patients and the severity of gastrointestinal diseases. . 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. . The prevalence of mixed infections of all -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 ( < 0.05). . mixed infections show high genetic diversity that may enhance bacterial adaptation to the hostile environment of the stomach and contribute to disease development.