Section for Zoonotic Ecology and Epidemiology, Linnaeus University, SE-391 82 Kalmar, Sweden.
Appl Environ Microbiol. 2010 Jul;76(13):4194-200. doi: 10.1128/AEM.01219-09. Epub 2010 May 7.
Campylobacter jejuni is a recognized and common gastrointestinal pathogen in most parts of the world. Human infections are often food borne, and the bacterium is frequent among poultry and other food animals. However, much less is known about the epidemiology of C. jejuni in the environment and what mechanisms the bacterium depends on to tolerate low pH. The sensitive nature of C. jejuni stands in contrast to the fact that it is difficult to eradicate from poultry production, and even more contradictory is the fact that the bacterium is able to survive the acidic passage through the human stomach. Here we expand the knowledge on C. jejuni acid tolerance by looking at protozoa as a potential epidemiological pathway of infection. Our results showed that when C. jejuni cells were coincubated with Acanthamoeba polyphaga in acidified phosphate-buffered saline (PBS) or tap water, the bacteria could tolerate pHs far below those in their normal range, even surviving at pH 4 for 20 h and at pH 2 for 5 h. Interestingly, moderately acidic conditions (pH 4 and 5) were shown to trigger C. jejuni motility as well as to increase adhesion/internalization of bacteria into A. polyphaga. Taken together, the results suggest that protozoa may act as protective hosts against harsh conditions and might be a potential risk factor for C. jejuni infections. These findings may be important for our understanding of C. jejuni passage through the gastrointestinal tract and for hygiene practices used in poultry settings.
空肠弯曲菌是世界上大多数地区公认的常见胃肠道病原体。人类感染通常是食源性的，该细菌在禽类和其他食用动物中很常见。然而，人们对环境中空肠弯曲菌的流行病学以及该细菌依赖什么机制来耐受低 pH 值的了解要少得多。空肠弯曲菌对酸敏感，这与它难以从禽类生产中根除形成鲜明对比，更矛盾的是，该细菌能够在胃酸的酸性环境中存活。在这里，我们通过观察原生动物作为感染的潜在流行病学途径，扩展了对空肠弯曲菌耐酸能力的认识。我们的研究结果表明，当空肠弯曲菌细胞与变形虫共培养在酸化的磷酸盐缓冲盐水（PBS）或自来水中时，细菌能够耐受远低于其正常范围的 pH 值，甚至在 pH 值为 4 时存活 20 小时，在 pH 值为 2 时存活 5 小时。有趣的是，中等酸性条件（pH 值 4 和 5）被证明会引发空肠弯曲菌的运动，并增加细菌进入变形虫的黏附和内化。总的来说，这些结果表明原生动物可能作为保护性宿主来对抗恶劣条件，并且可能是空肠弯曲菌感染的一个潜在危险因素。这些发现可能对我们理解空肠弯曲菌通过胃肠道的过程以及在禽类环境中使用的卫生实践很重要。
