Several virulence factors involving H. pylori-induced pathogenesis and the underlying mechanisms have led to different clinical sequelae [5–7]. Vacuolating cytotoxin (VacA), one of the major virulence factors secreted from H. pylori, has been detected in bacterial culture supernatants . Upon H. pylori colonization on cells, bacterial surface-contacted VacA is secreted directly from bacteria, followed by the intoxication of cells by vacuolation . Previous studies reported that vacA was diversified among clinical H. pylori isolates, particularly in the region encoding the signal sequence (type s1 or s2) and the mid-region (type m1 or m2) . Additionally, the distribution of vacA alleles varies among different geographic regions [11–14].