Attenuated Legionella pneumophila Survives for a Long Period in an Environmental Water Site.
Attenuated Legionella pneumophila Survives for a Long Period in an Environmental Water Site.
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减毒的嗜肺军团菌在环境水源中存活很长一段时间。
DOI：
10.1155/2019/8601346
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Watarai Masahisa
中科院分区：
文献类型：
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作者：
Nishida Takashi;Nakagawa Natsuko;Watanabe Kenta;Shimizu Takashi;Watarai Masahisa
嗜肺军团菌是一种常见的人类病原体，广泛存在于自然和人工水生环境中。许多研究揭示了L.还报道了嗜肺性临床菌株和许多表征环境菌株的研究。然而，在环境中的毒力和生存能力之间的关联尚不清楚。在本研究中，L.从环境水场所（Ashiyu足疗、饮水机、公共浴池）中分离到嗜肺菌，并对分离菌株进行血清学鉴定。发现分离菌株属于血清群SG 1、SG 2、SG 3、SG 4、SG 5、SG 8、SG 9和SG 13。还获得了无法分型的菌株。分离的菌株用于人单核细胞系THP-1中的细胞内生长测定。在这些菌株中，只有一种无法分型的菌株AY 3未能在THP-1中复制。此外，AY 3在环境水站点Ashiyu foot spa 2中保持了很长一段时间。此外，我们比较了从Ashiyu foot spa 2分离的几种菌株和临床菌株Togus‐1的特征。AY 3未能在THP-1细胞中复制，但在变形虫模型Dictyosteelium discoideum中复制。与Togus‐1相比，环境菌株在胁迫条件下的可培养细胞数更高。此外，评估了生物膜形成，并且AY 3显示出与Togus-I相同程度的生物膜形成。生物膜的形成，在变形虫中的复制，以及对压力因素的抗性将解释AY 3在一个环境站点的优势。虽然AY 3在THP-1细胞或阿米巴中复制能力差异的机制尚不清楚，但AY 3可能放弃在THP-1细胞中复制的能力，以便在一种环境中长期存活。了解L.嗜肺菌在不同宿主中的复制有助于控制军团病，但仍需进一步研究。
Legionella pneumophilais known as a human pathogen and is ubiquitous in natural and artificial aquatic environments. Many studies have revealed the virulence traits ofL. pneumophilausing clinical strains and a number of studies for characterizing environmental strains are also reported. However, the association between the virulence and survivability in the environment is unclear. In the present study,L. pneumophilawas isolated from environmental water sites (Ashiyu foot spa, water fountain, and public bath), and the serogroups of isolated strains were determined by serological tests. Isolated strains were found to belong to serogroups SG1, SG2, SG3, SG4, SG5, SG8, SG9, and SG13. Untypeable strains were also obtained. Isolated strains were used for intracellular growth assay in a human monocytic cell line, THP‐1. Among these strains, only an untypeable strain, named AY3, failed to replicate in THP‐1. In addition, AY3 was maintained for a long period in an environmental water site, Ashiyu foot spa 2. Further, we compared the characteristics of several strains isolated from Ashiyu foot spa 2 and a clinical strain, Togus‐1. AY3 failed to replicate in THP‐1 cells but replicated in an amoeba model,Dictyostelium discoideum. Compared with Togus‐1, the culturable cell number of environmental strains under stress conditions was higher. Moreover, biofilm formation was assessed, and AY3 showed the same degree of biofilm formation as Togus‐1. Biofilm formation, replication in amoebae, and resistance against stress factors would explain the predominance of AY3 at one environmental site. Although the mechanism underlying the difference in the ability of AY3 to replicate in THP‐1 cells or amoebae is still unclear, AY3 may abandon the ability to replicate in THP‐1 cells to survive in one environment for a long period. Understanding the mechanisms ofL. pneumophilain replication within different hosts should help in the control of Legionnaires’ disease, but further study is necessary.