As shown in Figure 2A, the predominant bacterial phyla in the two ulcer types were Proteobacteria, Bacteroidetes, and Firmicutes. It was noteworthy that Proteobacteria accounted for the major proportion in the Hp positive gastric antrum ulcers, whereas Bacteroidetes and Firmicutes accounted for the major proportion in the Hp positive duodenal ulcers, and the difference was statistically significant (p < 0.05, x2 test). Here, HP is linked to duodenal ulcer.