Study of the CagA Gene Prevalence in Helicobacter Pylori Strains Isolated from Patients with Upper Gastrointestinal Disorders in Iran

Introduction and Helicobacter pylori commonly is associated with gastritis: but only sometimes it causes clinically significant diseases such as gastric and duodenal ulcer. The development of disease depends on the virulence of the infecting H. pylori strain, the susceptibility of the host, and environment co-factors. The cytotoxin associated protein encoded by cagA gene is an important virulence factor that is produced by some H. pylori strains, and has been used as virulence marker in some populations. The aim of the study was to examine the prevalence of cagA gene in the isolated strains of H. pylori from patients with dyspeptic disease and to investigate the association of cagA gene and the severity of H. pylori related diseases in Iran. In this study, biopsy specimens were obtained from the antrum of 180 patients. After isolation of H. pylori and its DNA by standard methods, polymerase chain reaction (PCR) technique was used for detection of cagA bacterial gene. 92 out of the 180 patients had H. pylori strains. 70% were cagA gene positive. All patients with peptic ulcer (100%) and 44 out of 72 (61%) patients with non-ulcer dyspepsia were cagA positive (p<0.01). There was significant difference in frequency of cagA gene in peptic ulcer disease and non-ulcer dyspepsia (p‹0.01). It showed that the risk of PUD in patients with cagA+ H. pylori infection may be higher than in those with cagA- H. pylori infection.