ABSTRACT
To asses the status of two representative genes of cag PAl i.e cagA and cagE of Helicobacter pylori strains infecting Iranian patients suffered from various clinical outcomes using one-step PCR. A total of 120 H. pylori infected patients including non-ulcer dyspepsia, NUD [n=81], peptic ulcer disease, PUD [n=17], and gastric carcinoma, GC [n=22] referred for endoscopy or gastric resection to Amir Alam Hospital or Cancer Institute from 2005 to 2008 were assessed. The status of cagA and cagE genes was determined by gene specific PCR. 84.2% and 90.8% of the tested strains were positive for cagA and cage, respectively. 81.7% strains were positive for both cagA and cagE genes, whereas 8 [6.7%] were found double negative. The prevalence of cagA in GC patients [100%] was slightly higher than PUD patients [94.1%]. All of GC cases were infected with cagA-positive strains. The same distribution pattern was indicated for cagE gene in GC and PUD patients. The cagA-positive strains were significantly associated with GC as compared with NUD [P< 0.05] but this association did not gain statistical significance when cagE gene was assessed. The concurrent detection of cagA/cagE genes allowed rapid and specific clarification of cag PAI status. The strains with cagA/cagE genotype are predominant in Iran regardless of clinical outcome and create a distinct cluster pattern from those in the West and similar to those of East Asian countries. The current study also demonstrated that cagE gene can be explored as a better indication of cag-PAI in Iranian H. pylori strains
Subject(s)
Humans , Antigens, Bacterial , Bacterial Proteins , Peptic Ulcer , Stomach Ulcer , Polymerase Chain Reaction , Cross-Sectional Studies , DNAABSTRACT
The gastric pathogen Helicobacter pylori is introduced as an etiologic agent of gastritis and peptic ulcer and is associated with development of gastric adenocarcinoma. One of the most studied virulence marker of H. pylori is cytotoxin-associated gene A [cagA] with significant geographical heterogeneity around the world. This study was undertaken to assess the status of cagA gene of H .pylori strains infecting Iranian patients suffering from various gastrointestinal diseases and to evaluate the detection of this gene as a screening marker of high-risk patients. In this study, 180 patients [Mean age: 44 years] with upper gastrointestinal manifestations referred for endoscopy to Amir-Alam Hospital or Cancer Institute in Tehran were included. Among one hundred twenty H. pylori infected patients 81, 17 and 22 had non-ulcer dyspepsia [NUD], peptic ulcer disease [PUD], and gastric carcinoma [GC] respectively. Tissue samples were homogenized and incubation was performed up to 5 days. Identification was based on morphology under Gram staining and biochemical tests. The status of conserved region of cagA gene was determined by gene specific PCR. For statistical analysis, chi square test was used. Among the 180 of studied patients, 120 H. pylori strains were isolated. One hundred and one [84.2%] of the tested strains were positive for cagA and the remaining strains [15.8%] were negative. All of gastric cancer cases were infected with cagA -positive strains. The cagA -positive strains were significantly associated with GC as compared with NUD [p < 0.05] but this association did not gain statistical significance for other clinical outcomes. Although the possession of cagA is associated with GC when compared to NUD, due to the uniform distribution of cagA in all other disease categories detection of cagA alone can not be considered as a discriminative marker for a specific clinical outcome. Hence, the study of other virulence determinants and functional characteristics of cagA gene might be necessary for screening high risk patients