S100A8 and chronic gastritis: The aims of this work were: (i) to determine the prevalence of H. pylori by type of chronic gastritis; (ii) to determine the frequency of cagA, babA2 and vacA genotypes in H. pylori strains isolated from Mexican patients diagnosed with different types of chronic gastritis; and (iii) to characterize the variable region of cagA alleles that encode the C-terminal region of CagA in order to determine the type and number of EPIYA motifs, as well as the frequency of their combinations.