军团菌属是革兰氏阴性杆菌γ-变形菌，普遍存在于淡水环境、湿润土壤和堆肥材料中。人主要通过吸入受污染的人造水源（如淋浴、热水浴缸、管道和空调系统）产生的含有军团菌的气溶胶而感染军团菌。50岁以上的男性、吸烟人群和有潜在疾病（如糖尿病、癌症或免疫抑制）的个体患军团病的风险更高。夏季和初秋是军团菌感染的高峰期。
军团菌属约包括65个物种，可分为70多个血清型。不是所有的军团菌都能导致军团病，绝大多数临床感染（~90%）病例由嗜肺军团菌引发，其中血清型1菌株约占军团病的90%。L. longbeachae、L. bozemanii和L. micdadei导致的军团病占全球感染的2-7%。L. longbeachae是澳大利亚和新西兰军团病的主要病原菌（~30%）。与嗜肺军团菌相比，非嗜肺军团菌（non-Lpn）引起的肺炎较为罕见，且几乎全为院内感染。
军团菌属在环境中无处不在，变形虫是其天然宿主。变形虫对军团菌具有双重作用，既可为细菌提供胞内复制的栖息环境，又可保护其免受抗生素、化学物质、高温、渗透压等恶劣环境的影响。军团菌在环境中的持久存在也主要归因于其在自然和人工造淡水环境中生物膜的定植。生物膜的表型变异受细菌群体感应系统、转录因子LvbR以及温度的共同调控。
军团菌属编码一种高度保守的IVB型分泌系统（T4SS），称为Dot/Icm系统。Dot/Icm T4SS系统对胞内复制至关重要，它能将数百种细菌毒力因子（效应蛋白）直接转运到宿主细胞中。Dot/Icm转运的效应蛋白具有多种功能和生化活性，可干扰溶酶体对细菌的降解过程，并从宿主细胞中获取营养物质。
Samples collection date:
Samples host information:
Serotype information:
Samples MLST information:
Samples Virulence information:
Samples Resistance information:
[1] Newton H J, Ang D K, van Driel I R, et al. Molecular pathogenesis of infections caused by Legionella pneumophila[J]. Clin Microbiol Rev, 2010, 23(2): 274-98.
[2] Blatt S P, Parkinson M D, Pace E, et al. Nosocomial Legionnaires' disease: aspiration as a primary mode of disease acquisition[J]. Am J Med, 1993, 95(1): 16-22.
[3] Cunha C B, Cunha B A. Legionnaire's Disease Since Philadelphia: Lessons Learned and Continued Progress[J]. Infect Dis Clin North Am, 2017, 31(1): 1-5.
[4] Laura G V, Alvaro C O, Iñaki C, et al. Evolutionary Dissection of the Dot/Icm System Based on Comparative Genomics of 58 Legionella Species[J]. Genome Biology and Evolution, 2019, (9): 9.
[5] Khodr A, Kay E, Gomez-Valero L, et al. Molecular epidemiology, phylogeny and evolution of Legionella[J]. Infection Genetics & Evolution Journal of Molecular Epidemiology & Evolutionary Genetics in Infectious Diseases, 2016, 43: 108-122.
[6] Muder R R, Yu V L. Infection due to Legionella species other than L. pneumophila[J]. Clin Infect Dis, 2002, 35(8): 990-8.
[7] Mondino S, Schmidt S, Rolando M, et al. Legionnaires' Disease: State of the Art Knowledge of Pathogenesis Mechanisms of Legionella[J]. Annu Rev Pathol, 2020, 15: 439-466.
[8] Chauhan D, Shames S R. Pathogenicity and Virulence of Legionella: Intracellular replication and host response[J]. Virulence, 2021, 12(1): 1122-1144.
[9] Hoffmann C, Harrison C F, Hilbi H. The natural alternative: protozoa as cellular models for Legionella infection[J]. Cell Microbiol, 2014, 16(1): 15-26.
[10] Personnic N, Striednig B, Hilbi H. Quorum sensing controls persistence, resuscitation, and virulence of Legionella subpopulations in biofilms[J]. Isme j, 2021, 15(1): 196-210.
[11] Gomez-Valero L, Rusniok C, Carson D, et al. More than 18,000 effectors in the Legionella genus genome provide multiple, independent combinations for replication in human cells[J]. Proc Natl Acad Sci U S A, 2019, 116(6): 2265-2273.