Atlas R M
Department of Biology, University of Louisville, KY 40292, USA.
Environ Microbiol. 1999 Aug;1(4):283-93. doi: 10.1046/j.1462-2920.1999.00046.x.
Studies on Legionella show a continuum from environment to human disease. Legionellosis is caused by Legionella species acquired from environmental sources, principally water sources such as cooling towers, where Legionella grows intracellularly in protozoa within biofilms. Aquatic biofilms, which are widespread not only in nature, but also in medical and dental devices, are ecological niches in which Legionella survives and proliferates and the ultimate sources to which outbreaks of legionellosis can be traced. Invasion and intracellular replication of L. pneumophila within protozoa in the environment play a major role in the transmission of Legionnaires' disease. Protozoa provide the habitats for the environmental survival and reproduction of Legionella species. L. pneumophila proliferates intracellularly in various species of protozoa within vacuoles studded with ribosomes, as it also does within macrophages. Growth within protozoa enhances the environmental survival capability and the pathogenicity (virulence) of Legionella. The growth requirements of Legionella, the ability of Legionella to enter a viable non-culturable state, the association of Legionella with protozoa and the occurrence of Legionella within biofilms complicates the detection of Legionella and epidemiological investigations of legionellosis. Polymerase chain reaction (PCR) methods have been developed for the molecular detection of Legionella and used in environmental and epidemiological studies. Various physical and chemical disinfection methods have been developed to eliminate Legionella from environmental sources, but gaining control of Legionella in environmental waters, where they are protected from disinfection by growing within protozoa and biofilms, remains a challenge, and one that must be overcome in order to eliminate sporadic outbreaks of legionellosis.
对军团菌的研究表明，从环境到人类疾病存在一个连续过程。军团菌病是由从环境来源获取的军团菌引起的，主要是水源，如冷却塔，军团菌在生物膜内的原生动物细胞内生长。水生生物膜不仅广泛存在于自然界，也存在于医疗和牙科设备中，是军团菌生存和繁殖的生态位，也是军团菌病暴发的最终源头。嗜肺军团菌在环境中原生动物内的侵袭和细胞内复制在军团病传播中起主要作用。原生动物为军团菌的环境生存和繁殖提供了栖息地。嗜肺军团菌在充满核糖体的液泡内的各种原生动物细胞内增殖，就像在巨噬细胞内一样。在原生动物内生长增强了军团菌的环境生存能力和致病性（毒力）。军团菌的生长需求、进入活的非可培养状态的能力、与原生动物的关联以及在生物膜内的存在，使军团菌的检测和军团菌病的流行病学调查变得复杂。聚合酶链反应（PCR）方法已被开发用于军团菌的分子检测，并用于环境和流行病学研究。已开发出各种物理和化学消毒方法以从环境来源中消除军团菌，但要控制环境水体中的军团菌仍然是一项挑战，因为它们在原生动物和生物膜内生长从而免受消毒影响，而要消除军团菌病的散发病例，这一挑战必须被克服。
