Effect of Intracellular Resuscitation of <i>Legionella pneumophila</i> in <i>Acanthamoeba polyphage</i> Cells on the Antimicrobial Properties of Silver and Copper

Hwang, Myoung Goo; Katayama, Hiroyuki; Ohgaki, Shinichiro

doi:10.1021/es060412t

Cited by 45 publications

(36 citation statements)

References 27 publications

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“…Similar studies have reported Burkholderia pseudomallei as being more resistant to monochloramine, chlorine and UV once it is protected in Acanthamoeba astronyxis trophozoites (Howard and Inglis 2005). A decreased efficacy of silver and copper was reported against Legionella pneumophila and Pseudomonas aeruginosa within Acanthamoeba polyphaga trophozoites (Hwang et al 2006). Growth in different amoebal hosts may also influence the biocide susceptibility of a particular bacterial strain; this was recently evidenced with L. pneumophila replicated from Hartmannella vermiformis which displayed greater resistance to chlorine than cells replicated from A. castellanii (Chang et al 2009).…”

Section: Pathogen Protection In Multispecies Biofilmssupporting

confidence: 58%

Resistance of bacterial biofilms to disinfectants: a review

et al. 2011

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A biofilm can be defined as a community of microorganisms adhering to a surface and surrounded by a complex matrix of extrapolymeric substances. It is now generally accepted that the biofilm growth mode induces microbial resistance to disinfection that can lead to substantial economic and health concerns. Although the precise origin of such resistance remains unclear, different studies have shown that it is a multifactorial process involving the spatial organization of the biofilm. This review will discuss the mechanisms identified as playing a role in biofilm resistance to disinfectants, as well as novel anti-biofilm strategies that have recently been explored.

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Section: Pathogen Protection In Multispecies Biofilmssupporting

confidence: 58%

Resistance of bacterial biofilms to disinfectants: a review

et al. 2011

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“…Still, Acanthamoeba spp. are frequently used to study proliferation and growth of L. pneumophila within freeliving protozoa and numbers between Ͼ1.0 ϫ 10 2 and 4.5 ϫ 10 4 CFU of L. pneumophila per amoeba or vesicle have been reported (18,22,24,43,44). Growth of Acanthamoeba spp.…”

Section: Discussionmentioning

confidence: 99%

Detection of Protozoan Hosts for Legionella pneumophila in Engineered Water Systems by Using a Biofilm Batch Test

Valster

Wullings

Kooij

2010

Appl Environ Microbiol

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Legionella pneumophila proliferates in aquatic habitats within free-living protozoa, 17 species of which have been identified as hosts by using in vitro experiments. The present study aimed at identifying protozoan hosts for L. pneumophila by using a biofilm batch test (BBT). Samples (600 ml) collected from 21 engineered freshwater systems, with added polyethylene cylinders to promote biofilm formation, were inoculated with L. pneumophila and subsequently incubated at 37°C for 20 days. Growth of L. pneumophila was observed in 16 of 18 water types when the host protozoan Hartmannella vermiformis was added. Twelve of the tested water types supported growth of L. pneumophila or indigenous Legionella anisa without added H. vermiformis. In 12 of 19 BBT flasks H. vermiformis was indicated as a host, based on the ratio between maximum concentrations of L. pneumophila and H. vermiformis, determined with quantitative PCR (Q-PCR), and the composition of clone libraries of partial 18S rRNA gene fragments. Analyses of 609 eukaryotic clones from the BBTs revealed that 68 operational taxonomic units (OTUs) showed the highest similarity to free-living protozoa. Forty percent of the sequences clustering with protozoa showed >99.5% similarity to H. vermiformis. None of the other protozoa serving as hosts in in vitro studies were detected in the BBTs. In several tests with growth of L. pneumophila, the protozoa Diphylleia rotans, Echinamoeba thermarum, and Neoparamoeba sp. were identified as candidate hosts. In vitro studies are needed to confirm their role as hosts for L. pneumophila. Unidentified protozoa were implicated as hosts for uncultured Legionella spp. grown in BBT flasks at 15°C.Legionella pneumophila, the causative agent of Legionnaires' disease, is a common inhabitant of natural freshwater environments and human-made water systems, including cooling towers, whirlpools, air-conditioning systems, and installations for warm tap water (14). In the aquatic environment L. pneumophila proliferates within certain free-living protozoa, which serve as its hosts (15,30,59). Environmental factors favoring the growth and survival of L. pneumophila in freshwater systems include a water temperature between 20°C and 45°C (41, 60) and the presence of biofilms and sediments on which the protozoan hosts can graze (30,41,56).Rowbotham (44) was the first to report the growth of L. pneumophila within free-living amoebae, which belonged to the genera Acanthamoeba and Naegleria. In vitro studies with cocultures have revealed that 14 species of amoebae, viz., Acanthamoeba spp. (1, 35, A number of the free-living protozoa mentioned above and others, e.g., Vannella spp. and Saccamoeba spp., have been observed in aquatic environments from which L. pneumophila was cultivated or in which it was detected with PCR (4, 42, 51, 52). However, it remains unknown which of these protozoa actually serve as hosts for L. pneumophila in the aquatic environment, including human-made water systems. Moreover, it cannot be excluded that free-living protozoa oth...

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“…It has been shown that unculturable L. pneumophila may resuscitate to a fully virulent form by passage through an amoebal host (30,33,34,36) and therefore provide a largely undetected source of infections. Unculturable Legionellae have been observed for example after prolonged incubation in laboratory tap water microcosms at different temperatures, including elevated temperature at 42°C (36), heat shock (50 -70°C) (37), following disinfection (31)(32)(33), and after treatment with heavy metals (38).…”

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confidence: 99%

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

Auraß

Gerlach

Becher

et al. 2016

Molecular & Cellular Proteomics

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Major differences in the transcriptional program underlying the phenotypic switch between exponential and post-exponential growth of Legionella pneumophila were formerly described characterizing important alterations in infection capacity. Additionally, a third state is known where the bacteria transform in a viable but nonculturable state under stress, such as starvation. We here describe phase-related proteomic changes in exponential phase (E), postexponential phase (PE) bacteria, and unculturable microcosms (UNC) containing viable but nonculturable state cells, and identify phasespecific proteins. We present data on different bacterial subproteomes of E and PE, such as soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins. In total, 1368 different proteins were identified, 922 were quantified and 397 showed differential abundance in E/PE. The quantified subproteomes of soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins; 841, 55, and 77 proteins, respectively, were visualized in Voronoi treemaps. 95 proteins were quantified exclusively in E, such as cell division proteins MreC, FtsN, FtsA, and ZipA; 33 exclusively in PE, such as motility-related proteins of flagellum biogenesis FlgE, FlgK, and FliA; and 9 exclusively in unculturable microcosms soluble whole cell proteins, such as hypothetical, as well as transport/binding-, and metabolism-related proteins. A high frequency of differentially abundant or phase-exclusive proteins was observed among the 91 quantified effectors of the major virulence-associated protein secretion system Dot/Icm (> 60%). 24 were E-exclusive, such as LepA/B, YlfA, MavG, Lpg2271, and 13 were PE-exclusive, such as RalF, VipD, Lem10. The growth phase-related specific abundance of a subset of Dot/Icm virulence effectors was confirmed by means of Western blotting. We therefore conclude that many effectors are predominantly abundant at either E or PE which suggests their phase specific function. The distinct temporal or spatial presence of such proteins might have important implications for functional assignments in the future or for use as lifestage specific markers for pathogen analysis. Molecular

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Effect of Intracellular Resuscitation of Legionella pneumophila in Acanthamoeba polyphage Cells on the Antimicrobial Properties of Silver and Copper

Cited by 45 publications

References 27 publications

Resistance of bacterial biofilms to disinfectants: a review

Resistance of bacterial biofilms to disinfectants: a review

Detection of Protozoan Hosts for Legionella pneumophila in Engineered Water Systems by Using a Biofilm Batch Test

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors

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