Helicobacter pylori cag pathogenicity island genes among dyspeptic patients with chronic gastritis

ABSTRACT

The cag pathogenicity island [cagPAI] is one of the major virulence determinants of Helicobacter pylori [H. pylori]. Acquiring virulent strains of H. pylori is associated with increased risk for the development of gastric ulcers or cancer. The aim of this study was to determine H. pylori cagPAI genes pattern among dyspeptic Egyptian patients and its correlation with the varying degrees of the associated chronic gastritis. Histopathological examination, urease test and polymerase chain reaction [PCR] assay were performed for gastric antral biopsies obtained from 106 dyspeptic patients undergoing upper endoscopy. DNA extracts from H. pylori positive cases were analyzed for the presence of cagPAI genes cagA, cagE, cagM, tnpA, tnpB and cagT by using PCR assay. Apparently normal gastric mucosa was seen on endoscopy in 30.2% of dyspeptic patients while gastritis was diagnosed in 69.8% with significant difference [p<0.05]. H.pylori was detected in 71.7% of dyspeptic patients. A strong association was observed between H. pylori infection and gastritis patients [p<0.01]. The positivity rate of any of the cagPAI genes were 65.8% of H. pylori positive cases. Analysis of the entire cagPAI genes revealed that both cagA and cagE were the most predominant genes [30.2% , 18.4% respectively]. cagT and tnpB genes were not detected in all H. pylori positive gastric biopsies. The presence of the entire cagPAI genes was more substantiated in gastritis patients than in those with apparently normal mucosa [p<0.05]. The presence of cagA1/2, cagA3/4, cagM and cagE genes were significantly associated with moderate degree of gastritis [p<0.02], while tnpA gene was mostly detected in marked degree of gastritis [p<0.02]. In conclusion, it can be admitted that infection with virulent strain carrying cag PAI genes may be an indication of the risk of progression of gastric mucosal damage in chronic gastritis patients. In such country as Egypt where there is a high prevalence of H. pylori infection, cagPAI genotyping is important for prediction of the clinical outcome in H. pylori related gastritis aiming at eradication of infection before the progression to severe gastroduodenal diseases