Abstract: In order to assess the relationship between different HP bacteria types and their pathogenicity,investigated 1 674 patients who underwent gastroscopy and 100 blood donors. HP infection was diagnosed by at least 2 positive results from PCR, histology (Giemsa staining), or rapid urease test. Serum CagA IgG antibodies were measured by ELISA. It was found that total prevalence of CagA seropositive was 49.70% in patients and 38% in controls (P<0.05). The frequency of CagA antibodies were significantly higher in DU cases than that of in GU,GC and CG ones(P<0.01). In active and severe degree of CG, anti-CagA presence was more common(P<0.01). However, no difference was found in anti-CagA positive rate among GC, CAG, IM, AH and normal groups. These data indicated that specific HP strain with CagA seropositive was associated with the degree of damages and active inflammation on gastroduodenal mucosa.

Key words: Helicobacter pylori, cytotoxin-associated gene A, gastroduodenal diseases