广东地区幽门螺杆菌cagA基因与细菌定植及其致病性关系的研究

Relationship between cagA Gene of Helicobacter pylori Isolated from Guangdong Area and the Bacterial Colonization and its Pathogenicity

目的:分析广东地区细胞毒素相关基因(cagA)在幽门螺杆菌(H.pylori)中的分布情况及其与患者性别、年龄的关系;探讨H.pylori cagA在不同胃肠疾病发生中的作用及其与胃粘膜慢性炎症程度及H.pylori定植密度的关系。方法:采用改良Skirrow培养基分离培养得到191株H.pylori,用特定引物对各株细菌的cagA 3'端行聚合酶链反应(PCR)扩增鉴定;对其中83例患者再各取胃窦粘膜2块,经HE及Giemsa染色后观察胃粘膜慢性炎症程度及H.pylori定植密度。结果:广东地区H.pyloricagA阳性者占85.3%(163/191);H.pyloricagA阳性率与患者的性别、年龄无关;消化性溃疡及胃癌患者的H.pylori cagA阳性率显著高于慢性胃炎患者;cagA阳性H.pylori菌株在胃粘膜表面的定植密度较cagA阴性菌株更高,引起的胃粘膜慢性炎症也更为严重;H.pylori的定植密度与其引起的慢性炎症程度呈正相关。结论:广东地区cagA阳性H.pylori感染者占绝大多数;cagA阳性菌株较cagA阴性菌株具有更强的致病力,可能引起更为严重的胃肠道损害。

Aims: To investigate the distribution of cagA gene of Helicobacter pylori (H. pylori) in Guangdong area and analyse the relationship between cagA and patients' sex and age; to assess the role of cagA in H. pylori-related gastrointestinal diseases; to see if a link existed between H. pylori cagA and the degree of chronic gastric mucosal inflammation as well as the bacterial colonization density. Methods: 191 H. pylori strains were isolated using Skirrow culture plate. The 3'region of cagA was amplified by polymerase chain reaction (PCR) using specific primer. Two more specimens were biopsied from 83 patients' gastric antrum, then processed by HE and Giemsa stain to identify the degree of chronic gastric mucosal inflammation and bacterial colonization density. Results: In Guangdong area, H. pylori cagA positivity rate was 85.3% (163/191). There was no significant relationship between H. pylori cagA positivity rate and patients' sex and age; H. pylori cagA positivity rate was significantly higher in patients with peptic ulcer and gastric cancer than that in patients with chronic gastritis. The degree of chronic gastric mucosal inflammation and bacterial colonization density was more severe in cagA + H. pylori strains infection than that in cagA- H. pylori strains infection; There was positive correlation between bacterial colonization density and chronic gastric mucosal inflammation. Conclusions: cagA+ H. pylori strains are predominant in Guangdong area; The pathogenicity of cagA+ strains might be stronger than that of cagA- strains, and cagA+ strains infection can probably lead to more serious gastrointestinal diseases.