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目的研究细胞毒素相关抗原（ｃａｇＡ）基因在幽门螺杆菌（Ｈｐ）菌株中的分布，从而明确中国人感染Ｈｐ菌株的毒力状况。方法采用特异性引物扩增ＨｐｃａｇＡ基因的２９７ｂｐ片段，对７４个临床分离Ｈｐ菌株采用聚合酶链反应（ＰＣＲ）进行分型。同时收集患者的胃镜诊断及胃窦病理资料。结果９０．５％的Ｈｐ菌株含有ｃａｇＡ基因，其中消化性溃疡（ＰＵ）患者感染菌株ｃａｇＡ基因携带率（９４．９％）高于慢性胃炎患者（８５．７％），但二者差异无显著性（Ｐ＞０．０５）。病理资料显示，Ⅰ、Ⅱ型菌株均可引起胃窦的慢性炎症，但严重程度Ⅱ型菌株（ｃａｇＡ－）高于Ⅰ型（ｃａｇＡ＋，Ｐ＜０．０５），二者在致活动性胃炎、肠上皮化生、胃粘膜萎缩及淋巴滤泡形成方面比较，差异无显著性（Ｐ＞０．０５）。结论中国人感染ＨｐⅠ型菌株比例较西方国家高，但ｃａｇＡ基因尚不能作为区分Ｈｐ感染致不同胃肠道疾病的单一指标。
Objective To study the distribution of cytotoxin-associated antigen (cagA) gene in Helicobacter pylori (Hp) strains and to clarify the virulence of Hp strains in Chinese. Methods A 297bp fragment of HpcagA gene was amplified by specific primers and 74 strains of Hp isolates were genotyped by polymerase chain reaction (PCR). At the same time, we collected the gastroscope diagnosis and gastric antrum pathology data. Results 90.5% of Hp strains contained cagA gene. The prevalence of cagA gene in patients with peptic ulcer (PU) was higher than that of chronic gastritis patients (94.9%) (85.7%), but the difference was insignificant (P> 0.05). Pathological data showed that type Ⅰ and type Ⅱ strains could cause chronic inflammation of gastric antrum, but the severity of type Ⅱ strain (cagA-) was higher than that of type Ⅰ (cagA +, P <0.05) Intestinal metaplasia, gastric mucosal atrophy and the formation of lymphoid follicles, the difference was not significant (P> 0.05). Conclusion The prevalence of Hp Ⅰ -type strains in Chinese is higher than that in western countries, but the cagA gene can not be used as a single marker to distinguish the different gastrointestinal diseases caused by Hp infection.