We then analyzed the association between mixed infections in H. pylori clinical isolates from patients and disease severity. As shown in Table 3, a total of 20 patients with H. pylori mixed infections, two patients (22.2%) with chronic gastritis, 10 patients (47.6%) with duodenal ulcer, 4 patients (18.2%) with gastric ulcer, and 4 patients (22.2%) with gastric carcinoma, had mixed infections. Additionally, patients with duodenal ulcer showed a higher prevalence of H. pylori mixed infection compared to that in other gastrointestinal diseases (P < 0.05). In all studied subjects, mixed infections of H. pylori strains were found in 20 (28.6%) patients.