Another virulence factor of H. pylori is the cag-pathogenicity island- (cag-PAI-) encoded type four secretion system, which mediates the translocation of cytotoxin-associated gene A (CagA) into host cells [15, 16]. Once translocated into cells, CagA is phosphorylated at one or more tyrosine phosphorylation motifs to induce cell pathogenesis . Diversity within cag-PAI is found among people from Eastern and Western parts of the world . Nearly all East Asian isolates carry cag-PAI, and one-half to two-thirds of the isolates from Western countries carry cag-PAI [19, 20]. Of note, cagA, cagE, and cagT were found to be present in 100% of the domestic strains isolated from patients in Taiwan . These findings indicate that H. pylori isolates possess unusually high genetic heterogeneity and are diverse in different geographic regions.