The heterogeneic distribution of Helicobacter pylori cag pathogenicity island reflects different pathologies in multiracial Malaysian population

BACKGROUND: Helicobacter pylori harbouring cag-pathogenicity island (cagPAI) which encodes type IV secretion system (T4SS) and cagA virulence gene are involved in inflammation of the gastric mucosa. We examined all the 27 cagPAI genes in 88 H. pylori isolates from patients of different ethnicities and examined the association of the intactness of cagPAI region with histopathological scores of the gastric mucosa. RESULTS: 96.6% (n = 85) of H. pylori isolates were cagPAI-positive with 22.4% (19/85) having an intact cagPAI, whereas 77.6% (66/85) had a partial/rearranged cagPAI. The frequency of cag2 and cag14 were found to be significantly higher in H. pylori isolated from Malays, whereas cag4 was predominantly found in Chinese isolates. The cag24 was significantly found in higher proportions in Malay and Indian isolates than in Chinese isolates. The intactness of cagPAI region showed an association with histopathological scores of the gastric mucosa. Significant association was observed between H. pylori harbouring partial cagPAI with higher density of bacteria and neutrophil activity, whereas strains lacking cagPAI were associated with higher inflammatory score. CONCLUSIONS: The genotypes of H. pylori strains with various cagPAI rearrangement associated with patients’ ethnicities and histopathological scores might contribute to the pathogenesis of H. pylori infection in a multi-ethnic population.