The patients infected by CagA strains possessing two or three EPIYA C segments showed decreased levels of PGI when compared with those with infection by CagA strains possessing ≤ 1 EPIYA C segment (duodenal ulcer: 179.67 ± 83.30 vs. 67.01 ± 34.30, respectively, p = 0.02 and gastritis: 109.26 ± 85.61 vs. 57.55 ± 34.61, respectively, p = 0.01). This evidence concerns the gene S100A8 and duodenal ulcer.