Legionella steelei sp. nov., isolated from human respiratory specimens in California, USA, and South Australia

Edelstein, Paul H.; Edelstein, M. A. C.; Shephard, Lisa; Ward, Kevin W.; Ratcliff, Rodney Μ.

doi:10.1099/ijs.0.035709-0

Cited by 20 publications

(6 citation statements)

References 16 publications

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“…This Legionella species grows robustly in amoebae but fails to multiply within macrophages, although the bacterium is not killed (Supplementary Figure S7), suggesting that L. steelei can also evade phagosome-lysosome fusion in macrophages. Similarly, Edelstein et al (2012) have previously shown Legionella protist grazers…”

Section: Discussionsupporting

confidence: 52%

“…steelei was originally isolated from the respiratory tract of a patient in Australia (Edelstein et al, 2012). This Legionella species grows robustly in amoebae but fails to multiply within macrophages, although the bacterium is not killed (Supplementary Figure S7), suggesting that L. steelei can also evade phagosome-lysosome fusion in macrophages.…”

Section: Discussionmentioning

confidence: 99%

“…As this species does not grow axenically at 37 1C (Edelstein et al, 2012), failure to multiply within human macrophages may be due to its restricted growth temperature. Though not an apparent human pathogen owing to its temperature growth restriction, L. steelei may represent an emerging human pathogen, as has been suggested for other amoebal pathogens (Lamoth and Greub, 2010).…”

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confidence: 99%

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Diverse protist grazers select for virulence-related traits in Legionella

et al. 2015

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It is generally accepted that selection for resistance to grazing by protists has contributed to the evolution of Legionella pneumophila as a pathogen. Grazing resistance is becoming more generally recognized as having an important role in the ecology and evolution of bacterial pathogenesis. However, selection for grazing resistance presupposes the existence of protist grazers that provide the selective pressure. To determine whether there are protists that graze on pathogenic Legionella species, we investigated the existence of such organisms in a variety of environmental samples. We isolated and characterized diverse protists that graze on L. pneumophila and determined the effects of adding L. pneumophila on the protist community structures in microcosms made from these environmental samples. Several unrelated organisms were able to graze efficiently on L. pneumophila. The community structures of all samples were markedly altered by the addition of L. pneumophila. Surprisingly, some of the Legionella grazers were closely related to species that are known hosts for L. pneumophila, indicating the presence of unknown specificity determinants for this interaction. These results provide the first direct support for the hypothesis that protist grazers exert selective pressure on Legionella to acquire and retain adaptations that contribute to survival, and that these properties are relevant to the ability of the bacteria to cause disease in people. We also report a novel mechanism of killing of amoebae by one Legionella species that requires an intact Type IV secretion system but does not involve intracellular replication. We refer to this phenomenon as 'food poisoning'.

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Section: Discussionsupporting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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Diverse protist grazers select for virulence-related traits in Legionella

et al. 2015

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“…This cluster is also closely related to L. tucsonensis and L. steelei (bootstrap values = 97–99%) , species isolated from humans after renal transplant and bronchitis infection, respectively (Thacker et al., ; Edelstein et al. ).…”

Section: Resultsmentioning

confidence: 84%

Diverse Legionella‐Like Bacteria Associated with Testate Amoebae of the Genus Arcella (Arcellinida: Amoebozoa)

Gomaa

Gersh

Cavanaugh

2018

J Eukaryotic Microbiology

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Diverse species of Legionella and Legionella-like amoebal pathogens (LLAPs) have been identified as intracellular bacteria in many amoeboid protists. There are, however, other amoeboid groups such as testate amoeba for which we know little about their potential to host such bacteria. In this study, we assessed the occurrence and diversity of Legionella spp. in cultures and environmental isolates of freshwater arcellinid testate amoebae species, Arcella hemispherica, Arcella intermedia, and Arcella vulgaris, via 16S rRNA gene sequence analyses and fluorescent in situ hybridization (FISH). Analysis of the 16S rRNA gene sequences indicated that A. hemispherica, A. intermedia, and A. vulgaris host Legionella-like bacteria with 94-98% identity to other Legionella spp. based on NCBI BLAST search. Phylogenetic analysis placed Legionella-like Arcella-associated bacteria (LLAB) in three different clusters within a tree containing all other members of Legionella and LLAPs. The intracellular localization of the Legionella within Arcella hosts was confirmed using FISH with a Legionella-specific probe. This study demonstrates that the host range of Legionella and Legionella-like bacteria in the Amoebozoa extends beyond members of "naked" amoebae species, with members of the testate amoebae potentially serving an ecological role in the dispersal, protection, and replication of Legionella spp. in natural environments.

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“…While L. pneumophila, Legionella steelei, Legionella dumoffii , and Legionella norrlandica are able to grow within A . castellanii , several other species including Legionella longbeachae, Legionella jordanis , and Legionella anisa are unable to do so (Neumeister et al, 1997 ; Edelstein et al, 2012 ; Rizzardi et al, 2014 ). Thus, the fate of both the bacterium and the host cell is greatly determined by the inherent properties of each organism.…”

Section: Factors Affecting the Outcome Of Legionella mentioning

confidence: 99%

From Many Hosts, One Accidental Pathogen: The Diverse Protozoan Hosts of Legionella

Boamah

Zhou

Ensminger

et al. 2017

Front. Cell. Infect. Microbiol.

171

137

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The 1976 outbreak of Legionnaires' disease led to the discovery of the intracellular bacterial pathogen Legionella pneumophila. Given their impact on human health, Legionella species and the mechanisms responsible for their replication within host cells are often studied in alveolar macrophages, the primary human cell type associated with disease. Despite the potential severity of individual cases of disease, Legionella are not spread from person-to-person. Thus, from the pathogen's perspective, interactions with human cells are accidents of time and space—evolutionary dead ends with no impact on Legionella's long-term survival or pathogenic trajectory. To understand Legionella as a pathogen is to understand its interaction with its natural hosts: the polyphyletic protozoa, a group of unicellular eukaryotes with a staggering amount of evolutionary diversity. While much remains to be understood about these enigmatic hosts, we summarize the current state of knowledge concerning Legionella's natural host range, the diversity of Legionella-protozoa interactions, the factors influencing these interactions, the importance of avoiding the generalization of protozoan-bacterial interactions based on a limited number of model hosts and the central role of protozoa to the biology, evolution, and persistence of Legionella in the environment.

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Legionella steelei sp. nov., isolated from human respiratory specimens in California, USA, and South Australia

Cited by 20 publications

References 16 publications

Diverse protist grazers select for virulence-related traits in Legionella

Diverse protist grazers select for virulence-related traits in Legionella

Diverse Legionella‐Like Bacteria Associated with Testate Amoebae of the Genus Arcella (Arcellinida: Amoebozoa)

From Many Hosts, One Accidental Pathogen: The Diverse Protozoan Hosts of Legionella

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