Duncan H E, Edberg S C
Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT, USA.
Crit Rev Microbiol. 1995;21(2):85-100. doi: 10.3109/10408419509113535.
In order for an infection to occur, the target organ must come in contact with sufficient microbes, the microbe must possess specific virulence factors, these virulence factors must be expressed, and the defenses of the organ system must be overcome. This dynamic process, which is ongoing in all living entities, can be described by the following relationship: [formula: see text] The establishment of infection first occurs in a particular organ. This phenomenon is known as tissue trophism and the association of microbes with organ systems governs the practice of clinical microbiology and infectious disease. With some microbes (e.g., Giardia, Cryptosporidium) the interaction with the particular organ is so specific that infections are almost always confined to one site; with others (e.g., Salmonella, enterovirus) the microbe has the potential to become systemic. When attempting to establish health risk assessment from microbes by contact with food and drinking water, one must therefore consider that the gastrointestinal tract is a complex organ system with a variety of specific host defense mechanisms. It is only when the microbe has particular virulence factors for sites in gastrointestinal tract, and the specific host defense mechanisms in the gastrointestinal tract are breached, that infection of this organ system occurs. Therefore, the general terms "immunosuppression" or "immunocompromise" are meaningless unless the specific immune defect is known. A description of the microbial virulence factors active against the gastrointestinal tract and the defense mechanisms of this organ system are reviewed to provide a biological basis health risk assessment and future food and drinking water regulations.
为了发生感染，靶器官必须接触到足够数量的微生物，微生物必须具备特定的毒力因子，这些毒力因子必须得以表达，并且器官系统的防御功能必须被突破。这个在所有生物体内持续进行的动态过程，可以用以下关系来描述：[公式：见正文]感染首先在特定器官中发生。这种现象被称为组织嗜性，微生物与器官系统的关联决定了临床微生物学和传染病学的实践。对于一些微生物（如贾第虫、隐孢子虫），与特定器官的相互作用非常特异，以至于感染几乎总是局限于一个部位；而对于其他微生物（如沙门氏菌、肠道病毒），则有可能扩散至全身。因此，当试图通过接触食物和饮用水来评估微生物对健康的风险时，必须考虑到胃肠道是一个具有多种特定宿主防御机制的复杂器官系统。只有当微生物具有针对胃肠道特定部位的特殊毒力因子，并且胃肠道的特定宿主防御机制被突破时，才会发生该器官系统的感染。所以，除非知道具体的免疫缺陷，否则“免疫抑制”或“免疫妥协”这些笼统的术语是没有意义的。本文综述了针对胃肠道起作用的微生物毒力因子以及该器官系统的防御机制，以提供健康风险评估以及未来食品和饮用水法规的生物学依据。
