Survival of Biofilm‐Associated <i>Legionella pneumophila</i> Exposed to Various Stressors

Vatansever, Cansu; Türetgen, Irfan

doi:10.2175/106143015x14212658613154

Cited by 10 publications

(6 citation statements)

References 40 publications

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“…Furthermore, differences between laboratory strains and Legionella strains isolated from natural environments is not limited to genetic variations and is also evident by different resistance to potential environmental stressors (e.g., temperature and oxidative stress) [ 27 ]. Legionella can persist in a wide range of environmental conditions, including pH, temperature, and NaCl concentrations [ 28 , 29 ] and in nature they frequently occupy oligotrophic environments [ 30 ]. Paradoxically, isolation requires highly permissive media, which includes various supplements and an optimized temperature, suggesting a fastidious nature [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

Sodium levels and grazing pressure shape natural communities of the intracellular pathogen Legionella

2023

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Background Legionella are parasites of freshwater protozoa, responsible for Legionellosis. Legionella can be found in a variety of aquatic environments, including rivers, lakes, and springs, as well as in engineered water systems where they can potentially lead to human disease outbarks. Legionella are considered to be predominantly freshwater organisms with a limited ability to proliferate in saline environments. Exposure of Legionella to high sodium concentrations inhibits growth and virulence of laboratory strains, particularly under elevated temperatures. Nonetheless, Legionella have been identified in some saline environments where they likely interact with various protozoan hosts. In this work, we examine how these selection pressures, sodium and grazing, help shape Legionella ecology within natural environments. Utilizing Legionella-specific primers targeting a variable region of the Legionella 16S rRNA gene, we characterized Legionella abundance, diversity, and community composition in natural spring clusters of varying sodium concentrations, focusing on high sodium concentrations and elevated temperatures. Results We observed the highest abundance of Legionella in spring clusters of high salinity, particularly in combination with elevated temperatures. Legionella abundance was strongly related to sodium concentrations. The Legionella community structure in saline environments was characterized by relatively low diversity, compared to spring clusters of lower salinity. The community composition in high salinity was characterized by few dominant Legionella genotypes, not related to previously described species. Protozoan microbial community structure and composition patterns resembled those of Legionella, suggesting a common response to similar selection pressures. We examined Legionella co-occurrence with potential protozoan hosts and found associations with Ciliophora and Amoebozoa representatives. Conclusions Our results indicate that selection forces in saline environments favor a small yet dominant group of Legionella species that are not closely related to known species. These novel environmental genotypes interact with various protozoan hosts, under environmental conditions of high salinity. Our findings suggest that alternative survival mechanisms are utilized by these species, representing mechanisms distinct from those of well-studied laboratory strains. Our study demonstrate how salinity can shape communities of opportunistic pathogens and their hosts, in natural environments, shedding light on evolutionary forces acting within these complex environments.

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Section: Introductionmentioning

confidence: 99%

Sodium levels and grazing pressure shape natural communities of the intracellular pathogen Legionella

2023

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“…Is well-known the distinct distribution pattern of legionellae between reservoirs. So, the ability of legionellae to reside, survive and multiply in biofilm communities that are known to provide protection and nutrients (Taylor et al, 2009 ; Declerck, 2010 ; Abdel-Nour et al, 2013 ; Vatansever and Türetgen, 2015 ) could represent crucial features for selection by environmental filtering and competition explaining the predominance of some disease-related strains. Indeed, despite the presence of diverse Legionella sp.…”

Section: Discussionmentioning

confidence: 99%

Differences in Virulence Between Legionella pneumophila Isolates From Human and Non-human Sources Determined in Galleria mellonella Infection Model

Sousa

Silva

Moreira

et al. 2018

Front. Cell. Infect. Microbiol.

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Legionella pneumophila is a ubiquitous bacterium in freshwater environments and in many man-made water systems capable of inducing pneumonia in humans. Despite its ubiquitous character most studies on L. pneumophila virulence focused on clinical strains and isolates from man-made environments, so little is known about the nature and extent of virulence variation in strains isolated from natural environments. It has been established that clinical isolates are less diverse than man-made and natural environmental strains, suggesting that only a subset of environmental isolates is specially adapted to infect humans. In this work we intended to determine if unrelated L. pneumophila strains, isolated from different environments and with distinct virulence-related genetic backgrounds, displayed differences in virulence, using the Wax Moth Galleria mellonella infection model. We found that all tested strains were pathogenic in G. mellonella, regardless of their origin. Indeed, a panoply of virulence-related phenotypes was observed sustaining the existence of significant differences on the ability of L. pneumophila strains to induce disease. Taken together our results suggest that the occurrence of human infection is not related with the increased capability of some strains to induce disease since we also found a concentration threshold above which L. pneumophila strains are equally able to cause disease. In addition, no link could be established between the sequence-type (ST) and L. pneumophila pathogenicity. We envision that in man-made water distribution systems environmental filtering selection and biotic competition acts structuring L. pneumophila populations by selecting more resilient and adapted strains that can rise to high concentration if no control measures are implemented. Therefore, public health strategies based on the sequence based typing (STB) scheme analysis should take into account that the major disease-associated clones of L. pneumophila were not related with higher virulence in G. mellonella infection model, and that potential variability of virulence-related phenotypes was found within the same ST.

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“…Since their discovery as the causative agent of Legionnaire's disease in 1976 [1], bacteria of the Legionella genus have become a major source of drinking water-related disease outbreaks [2]. Naturally occurring in water [3] and soil [4], Legionella possess traits that enable their survival in a wide variety of environmental conditions [5], including protozoan host parasitization [6]. Though numerous transmission sources have been implicated in the spread of legionellosis, transmission is thought to occur primarily through the inhalation of cells, commonly via aerosolized water from engineered systems [7].…”

Section: Introductionmentioning

confidence: 99%

Legionella Occurrence beyond Cooling Towers and Premise Plumbing

2021

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Legionella is an environmental pathogen that is responsible for respiratory disease and is a common causative agent of water-related outbreaks. Due to their ability to survive in a broad range of environments, transmission of legionellosis is possible from a variety of sources. Unfortunately, a disproportionate amount of research that is devoted to studying the occurrence of Legionella in environmental reservoirs is aimed toward cooling towers and premise plumbing. As confirmed transmission of Legionella has been linked to many other sources, an over-emphasis on the most common sources may be detrimental to increasing understanding of the spread of legionellosis. This review aims to address this issue by cataloguing studies which have examined the occurrence of Legionella in less commonly investigated environments. By summarizing and discussing reports of Legionella in fresh water, ground water, saltwater, and distribution system drinking water, future environmental and public health researchers will have a resource to aid in investigating these pathogens in relevant sources.

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Survival of Biofilm‐Associated Legionella pneumophila Exposed to Various Stressors

Cited by 10 publications

References 40 publications

Sodium levels and grazing pressure shape natural communities of the intracellular pathogen Legionella

Sodium levels and grazing pressure shape natural communities of the intracellular pathogen Legionella

Differences in Virulence Between Legionella pneumophila Isolates From Human and Non-human Sources Determined in Galleria mellonella Infection Model

Legionella Occurrence beyond Cooling Towers and Premise Plumbing

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