Significance of dormant forms of Helicobacter pylori in ulcerogenesis

Nearly half of the global population are carriers of Helicobacter pylori(H. pylori),a Gram-negative bacterium that persists in the healthy human stomach. H. pylori can be a pathogen and causes development of peptic ulcer disease in a certain state of the macroorganism. It is well established that H. pylori infection is the main cause of chronic gastritis and peptic ulcer disease(PUD). Decontamination of the gastric mucosa with various antibiotics leads to H. pylori elimination and longer remission in this disease. However,the reasons for repeated detection of H. pylori in recurrent PUD after its successful eradication remain unclear. The reason for the redetection of H. pylori in recurrent PUD can be either reinfection or ineffective anti-Helicobacter therapy. The administration of antibacterial drugs can lead not only to the emergence of resistant strains of microorganisms,but also contribute to the conversion of H. pylori into the resting(dormant) state. The dormant forms of H. pylori have been shown to play a potential role in the development of relapses of PUD. The paper discusses morphological H. pylori forms,such as S-shaped,C-shaped,U-shaped,and coccoid ones. The authors proposes the classification of H. pylori according to its morphological forms and viability.

Coccoid <i>Helicobacter pylori</i>Can Directly Adhere and Invade in Agminated Formation to Human Gastric Epithelial Cells

Helicobacter pylori (H. pylori) can infect into the epithelial cell to cause benign or malignant disorders. Under stressful environment, a spiral form of H. pylori is transformed into a coccoid form. The infectivity of the coccoid form is still controversial. Since spiral forms are transformed into two types of coccoid forms via different mechanisms, the infectivity of the two types of coccoid forms into human gastric epithelial cell was examined. A laboratory and a clinical strain of H. pyloriv were cultured in liquid medium under different conditions to produce the two types of coccoid forms. These coccoid H. pylorisv were then co-cultured with human derived gastric epithelial cell, MKN-28. Adhesion and penetration of bacteria into MKN-28 cells were monitored by scanning-, standard transmission- and immunotransmission-electron microscopy (SEM, TEM and ITEM). We observed that both coccoid forms were able to adhere onto the surface of MKN-28 cells in agminated formation and also penetrated into the gastric epithelial cells besides the spiral form of H. pyloriv. Coccoid H. pylori is not a passive entity but can actively infect the human gastric epithelial cell.

一种简便的幽门螺杆菌液体培养法的构建

目的:建立一种简便、有效的幽门螺杆菌(H.pylori)的液体培养法。方法:取脑心浸液9 m L、胎牛血清1 m L、H.pylori选择剂(万古霉素、头孢磺啶、甲氧氨苄嘧啶及两性霉素B)400μL制成H.pylori液体培养基,将H.pylori接种于H.pylori液体培养基,在厌氧罐中通过微需氧袋建立微需氧条件,于37℃振荡培养3 d,同时设立传统固体培养基培养的H.pylori作为对照;观察2种方法培养的H.pylori生长状况及H.pylori形态,比较2种方法培养的H.pylori的尿素酶、氧化酶及触酶试验结果。结果:固体培养到第3天时,H.pylori生长良好,哥伦比亚血琼脂平板上见透明、针尖样菌落形态;液体培养第3天时可见培养基明显浑浊,涂抹少量菌液于无抗生素的哥伦比亚血琼脂平板培养,肉眼未见污染菌生长,并有透明、针尖样的菌落长出;革兰染色后,固体培养基中的H.pylori为螺旋状、海鸥状、S状弯曲菌或短杆菌;液体培养基中的H.pylori则多为螺旋短杆状、亦见部分长丝状细菌,有的互相缠绕聚集成团,有的散在分布;取两种方法培养的H.pylori菌进行尿素酶、氧化酶及触酶试验,结果均为阳性。结论:成功建立一种简便、有效的H.pylori液体培养法,细菌生长良好,且H.pylori形态变长。

幽门螺杆菌的长丝体变异及返祖

我们采用改良Hp培养基(HBSV培养基)对Hp进行自然诱导,发现Hp球形变异体在含有适量蛋黄和血清的培养中容易返祖及传代,部分培养超过5天的菌落中有长丝体形成,或在球变体两侧形成长短不等的菌丝。长丝体变异的菌落与一般无异,但形态多较大,长丝体约为典型菌的3～10倍以上,菌体弯曲不规则或缠绕,粗细不均,胞壁缺陷,但可在普通渗透压的平板上生长。长丝体不稳定,接种于Hp或HBSV培养基返祖成典型的“S”形Hp。本研究提出这样的假说:Hp变异由典型“S”形→球变→长丝体和巨球体变异→返祖成典型Hp,Hp的这种变异可能存其传染和感染复发中起重要作用。

幽门螺杆菌形态变化超微结构分析

目的 幽门螺杆菌(Helicobacter pylori,Hp)在不利的生长环境下会由螺旋杆状转变为球形体,简称为球形变,球形状态下的Hp通常是存活但不可培养的(VBNC)。当环境适宜时球形体又回复为螺旋杆状。目前对于Hp球形变及其回复的完整形态变化过程尚不清楚,转变机制亦未被完全揭示。本研究以两株Hp标准菌株(SS1和26695)为对象,从形态及超微结构层面揭示Hp的球形变及回复过程。方法 利用透射电子显微镜负染和超薄切片技术捕捉Hp在球形变及回复过程中不同时间点的形态和超微结构变化,并对大视野下球形体和螺旋体计数,分析对比球形转变及回复实验中Hp形态变化的速度。结果 Hp SS1与26695菌株形态相似,但SS1有更多鞭毛表达。当Hp发生形态转变时,螺旋杆状的Hp会缩短长度并折叠为“U型”,细胞内膜与外膜分离,周质空间加大;细菌内部结构发生重塑,进而缩紧成球形体,球形体的体积通常小于其螺旋杆状形态时的体积。Hp的两种标准菌株在次优生长状态下,SS1球形化的速度和比例均大于26695,回复为螺旋杆状的速度却慢于26695。结论 Hp的形态较为灵活,在球形转化时会出现“U”形的中间过度状态,不同菌株的球形变和最佳生长状态时间差异很大,在形态转换期间Hp内外膜分离,形态不规则,体外和体内试验中均应考虑菌株状态对结果可能造成的影响。