Legionella -like slender rods multiplying within a strain of Acanthamoeba sp. isolated from drinking water

Michel, R.; Müller, Karl-Dieter; Amann, Rudolf; Schmid, Ernst N.

doi:10.1007/s004360050362

Cited by 28 publications

(15 citation statements)

References 15 publications

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“…Able to colonize water supply, cooling, and humidification systems, they also serve as amplification vehicles and possibly reservoirs for Mycobacterium avium and a variety of Legionella spp. ; even C. pneumoniae has been shown to survive and replicate within acanthamoebae (8,9,12,27,29,33,37). Such intraprotozoal multiplication followed by aerosolization and inhalation of bacterium-laden vesicles has been proposed as a mechanism to explain the epidemiology of legionellosis and the apparent lack of case-to-case spread (4,6).…”

Section: Discussionmentioning

confidence: 99%

Phylogenetic Diversity among Geographically Dispersed Chlamydiales Endosymbionts Recovered from Clinical and Environmental Isolates of Acanthamoeba spp

Fritsche¹,

Horn

Wagner

et al. 2000

Appl Environ Microbiol

134

123

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The recently proposed reorganization of the order Chlamydiales and description of new taxa are broadening our perception of this once narrowly defined taxon. We have recovered four strains of gram-negative cocci endosymbiotic in Acanthamoeba spp., representing 5% of the Acanthamoeba sp. isolates examined, which displayed developmental life cycles typical of members of the Chlamydiales. One of these endosymbiont strains was found stably infecting an amoebic isolate recovered from a case of amoebic keratitis in North America, with three others found in acanthamoebae recovered from environmental sources in North America (two isolates) and Europe (one isolate). Analyses of nearly full-length 16S rRNA gene sequences of these isolates by neighbor joining, parsimony, and distance matrix methods revealed their clustering with other members of the Chlamydiales but in a lineage separate from those of the genera Chlamydia, Chlamydophila, Simkania, and Waddlia (sequence similarities, <88%) and including the recently described species Parachlamydia acanthamoebae (sequence similarities, 91.2 to 93.1%). With sequence similarities to each other of 91.4 to 99.4%, these four isolates of intra-amoebal endosymbionts may represent three distinct species and, perhaps, new genera within the recently proposed family Parachlamydiaceae. Fluorescently labeled oligonucleotide probes targeted to 16S rRNA signature regions were able to readily differentiate two groups of intra-amoebal endosymbionts which corresponded to two phylogenetic lineages. These results reveal significant phylogenetic diversity occurring among the Chlamydiales in nontraditional host species and supports the existence of a large environmental reservoir of related species. Considering that all described species of Chlamydiales are known to be pathogenic, further investigation of intra-amoebal parachlamydiae as disease-producing agents is warranted.All members of the order Chlamydiales are recognized pathogens of mammals, marsupials, or birds. The ability to produce respiratory disease, among other clinical presentations, is a feature of most species within the order and is especially characteristic of infections produced by Chlamydophila pneumoniae, Chlamydophila psittaci, certain serovars of Chlamydia trachomatis, and the recently described species Simkania negevensis (20,21,23). The recent finding of evidence for seroconversion to antigen of Parachlamydia acanthamoebae, an intra-amoebal Chlamydia-like bacterium, in a small number of humans experiencing community-acquired pneumonia, along with the findings of novel Parachlamydia-related 16S rRNA sequences in respiratory specimens, peripheral blood, and aortic tissue, suggests that this and related species of protozoal endosymbionts may also be of clinical significance, warranting further investigation (2, 5, 30).Previously, we have reported on the common occurrence of uncultured bacterial endosymbionts in protozoa of the genus Acanthamoeba (13). While 20% of axenically growing Acanthamoeba isolates recovered from clini...

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Section: Discussionmentioning

confidence: 99%

Phylogenetic Diversity among Geographically Dispersed Chlamydiales Endosymbionts Recovered from Clinical and Environmental Isolates of Acanthamoeba spp

Fritsche¹,

Horn

Wagner

et al. 2000

Appl Environ Microbiol

134

123

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“…Then, additional LLAP were recovered from environmental sources (28,181). LLAP-9, LLAP-7FL (fluorescent), and LLAP-7NF (nonfluorescent) were also shown to be members of the species L. lytica (5), while LLAP-6, LLAP-10, and LLAP-12 represented three new species of Legionella: L. rowbothamii, L. fallonii, and L. drancourtii, respectively (5, 151).…”

Section: Legionellaceaementioning

confidence: 99%

“…Biofilms such as those found on contact lenses and dental unit water lines can support the growth of free-living amoebae (14,62). Free-living amoebae such as Hartmanella, Naegleria, and Acanthamoeba have also been recovered from drinking water (111,181), cooling towers (13), natural thermal water (200,201), swimming pools (59), hydrotherapy baths (60,215), and hospital water networks (206). Several free-living amoebae were also recovered from marine water.…”

Section: Introductionmentioning

confidence: 99%

Microorganisms Resistant to Free-Living Amoebae

2004

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Free-living amoebae feed on bacteria, fungi, and algae. However, some microorganisms have evolved to become resistant to these protists. These amoeba-resistant microorganisms include established pathogens, such as Cryptococcus neoformans, Legionella spp., Chlamydophila pneumoniae, Mycobacterium avium, Listeria monocytogenes, Pseudomonas aeruginosa, and Francisella tularensis, and emerging pathogens, such as Bosea spp., Simkania negevensis, Parachlamydia acanthamoebae, and Legionella-like amoebal pathogens. Some of these amoeba-resistant bacteria (ARB) are lytic for their amoebal host, while others are considered endosymbionts, since a stable host-parasite ratio is maintained. Free-living amoebae represent an important reservoir of ARB and may, while encysted, protect the internalized bacteria from chlorine and other biocides. Free-living amoebae may act as a Trojan horse, bringing hidden ARB within the human “Troy,” and may produce vesicles filled with ARB, increasing their transmission potential. Free-living amoebae may also play a role in the selection of virulence traits and in adaptation to survival in macrophages. Thus, intra-amoebal growth was found to enhance virulence, and similar mechanisms seem to be implicated in the survival of ARB in response to both amoebae and macrophages. Moreover, free-living amoebae represent a useful tool for the culture of some intracellular bacteria and new bacterial species that might be potential emerging pathogens

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“…Legionella-laden amoebae or amoebal vesicles and cysts harbouring bacteria might also be part of the inoculum that precipitates lung infection (Berk et al, 1998;Brieland et al, 1997). Amoebae belonging to the genera Acanthamoeba, Echinamoeba, Hartmannella, Naegleria, Vahlkampfia and Willaertia coexist with L. pneumophila in water habitats, and at least 20 species representing these genera support L. pneumophila intracellular growth (Anand et al, 1983;Barbaree et al, 1986;Buse & Ashbolt, 2011;Cianciotto & Fields, 1992;Declerck et al, 2007;Dey et al, 2009;Fields et al, 1989;Fields, 1996;Harada et al, 2010;Harf & Monteil, 1988;Henke & Seidel, 1986;Holden et al, 1984;Hsu et al, 2011;Michel et al, 1998;Miyamoto et al, 2003;Molmeret et al, 2001;Newsome et al, 1985;Rowbotham, 1980Rowbotham, , 1986Tyndall & Domingue, 1982;Wadowsky et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

The novel Legionella pneumophila type II secretion substrate NttC contributes to infection of amoebae Hartmannella vermiformis and Willaertia magna

2014

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The type II protein secretion (T2S) system of Legionella pneumophila secretes over 25 proteins, including novel proteins that have no similarity to proteins of known function. T2S is also critical for the ability of L. pneumophila to grow within its natural amoebal hosts, including Acanthamoeba castellanii, Hartmannella vermiformis and Naegleria lovaniensis. Thus, T2S has an important role in the natural history of legionnaires' disease. Our previous work demonstrated that the novel T2S substrate NttA promotes intracellular infection of A. castellanii, whereas the secreted RNase SrnA, acyltransferase PlaC, and metalloprotease ProA all promote infection of H. vermiformis and N. lovaniensis. In this study, we determined that another novel T2S substrate that is specific to Legionella, designated NttC, is unique in being required for intracellular infection of H. vermiformis but not for infection of N. lovaniensis or A. castellanii. Expanding our repertoire of amoebal hosts, we determined that Willaertia magna is susceptible to infection by L. pneumophila strains 130b, Philadelphia-1 and Paris. Furthermore, T2S and, more specifically, NttA, NttC and PlaC were required for infection of W. magna. Taken together, these data demonstrate that the T2S system of L. pneumophila is critical for infection of at least four types of aquatic amoebae and that the importance of the individual T2S substrates varies in a host cell-specific fashion. Finally, it is now clear that novel T2S-dependent proteins that are specific to the genus Legionella are particularly important for L. pneumophila infection of key, environmental hosts.

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Legionella -like slender rods multiplying within a strain of Acanthamoeba sp. isolated from drinking water

Cited by 28 publications

References 15 publications

Phylogenetic Diversity among Geographically Dispersed Chlamydiales Endosymbionts Recovered from Clinical and Environmental Isolates of Acanthamoeba spp

Phylogenetic Diversity among Geographically Dispersed Chlamydiales Endosymbionts Recovered from Clinical and Environmental Isolates of Acanthamoeba spp

Microorganisms Resistant to Free-Living Amoebae

The novel Legionella pneumophila type II secretion substrate NttC contributes to infection of amoebae Hartmannella vermiformis and Willaertia magna

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