Ecological analysis of Helicobacter pylori in oral cavities

幽门螺杆菌与胃窦慢性活动性炎症和十二指肠溃疡之间的强相关性已被确认。最近，一些分子生态学研究表明，幽门螺杆菌在患者的牙菌斑中检测到，这表明人类口腔是幽门螺杆菌的天然储存库。本研究采用聚合酶链反应（PCR）方法检测了60名健康志愿者牙菌斑中幽门螺杆菌（H.pylori）的密度，以了解H.pylori在牙菌斑中的感染情况。此外，我们通过PCR检测了幽门螺杆菌阳性患者口腔不同部位牙菌斑中幽门螺杆菌的存在。在11份唾液标本和10份牙菌斑标本中，有4份牙菌斑标本为幽门螺杆菌阳性，因此，我们得出结论，人类口腔可能是幽门螺杆菌的储存库。在分析过程中，我们发现DNA纯化步骤是我们用PCR方法检测牙菌斑中幽门螺杆菌的关键。我们还使用恒化器培养技术研究了生长条件对幽门螺杆菌生长和杆状至球状形态转化的影响。我们已经获得了一个稳定的状态培养幽门螺杆菌在一个相对较低的稀释率（0.04 h-1）下的微有氧条件。尽管生长速率相对较低，但在该培养物中未观察到形态转化。进一步的研究正在进行中，以确定在恒化器中受控条件下球形细胞形成的起始因素。

A strong association between Helicobacter pylori and chronic active inflammation of the gastric antrum and duodenal ulceration has been recognized. Recently, some molecular ecological studies showed that H.pylori was detected in the dental plaques of patients, suggesting that the human oral cavity represents the natural reservoir of H.pylori. In this study, to estimate the prevalence of H.pylori in human dental plaques, we attempted to measure the population density of H.pylori in the dental plaques of 60 healthy volunteers by the PCR method. Among the subjects, specimens (13%) were found to contain H.pylori DNA.Furthermore, we examined by PCR the existence of H.pylori in dental plaques from various sites in the oral cavity of a gastric H.pylori-positive patient. Of eleven specimens including saliva and 10 dental plaques taken, four specimens of dental plaques were H.pylori-positive.Therefore, it was concluded that human oral cavity is a possible reservoir of H.pylori During the analyses, we found that DNA purification step is critical to detection of H.pylori in dental plaques by our PCR method.To further our understanding of the ecology of H.pylori, we also studied the effect of growth conditions on the growth and bacillary-to-coccoid morphologic conversion of H.pylori using chemostat culture techniques. We have obtained a steady state culture of H.pylori at a relatively low dilution rate (0.04 h-1) under a microaerobi condition. Although the relatively low growth rate, no morphologic conversion was observed in that culture. Further studies are now in progress to ascertain the initiation factors of spherical cell formation under controlled condition in a chemostat.