scholarly journals Biodiversity of Amoebae and Amoeba-Resisting Bacteria in a Hospital Water Network

2006 ◽  
Vol 72 (4) ◽  
pp. 2428-2438 ◽  
Author(s):  
Vincent Thomas ◽  
Katia Herrera-Rimann ◽  
Dominique S. Blanc ◽  
Gilbert Greub
Keyword(s):  
Legionella Pneumophila ◽  
Strong Association ◽  
Acanthamoeba Castellanii ◽  
Control Measures ◽  
Water Network ◽  
Water Control ◽  
Domestic Water ◽  
Mycobacterium Xenopi ◽  
Hartmannella Vermiformis ◽  
Human Infections

ABSTRACT Free-living amoebae (FLA) are ubiquitous organisms that have been isolated from various domestic water systems, such as cooling towers and hospital water networks. In addition to their own pathogenicity, FLA can also act as Trojan horses and be naturally infected with amoeba-resisting bacteria (ARB) that may be involved in human infections, such as pneumonia. We investigated the biodiversity of bacteria and their amoebal hosts in a hospital water network. Using amoebal enrichment on nonnutrient agar, we isolated 15 protist strains from 200 (7.5%) samples. One thermotolerant Hartmannella vermiformis isolate harbored both Legionella pneumophila and Bradyrhizobium japonicum. By using amoebal coculture with axenic Acanthamoeba castellanii as the cellular background, we recovered at least one ARB from 45.5% of the samples. Four new ARB isolates were recovered by culture, and one of these isolates was widely present in the water network. Alphaproteobacteria (such as Rhodoplanes, Methylobacterium, Bradyrhizobium, Afipia, and Bosea) were recovered from 30.5% of the samples, mycobacteria (Mycobacterium gordonae, Mycobacterium kansasii, and Mycobacterium xenopi) were recovered from 20.5% of the samples, and Gammaproteobacteria (Legionella) were recovered from 5.5% of the samples. No Chlamydia or Chlamydia-like organisms were recovered by amoebal coculture or detected by PCR. The observed strong association between the presence of amoebae and the presence of Legionella (P < 0.001) and mycobacteria (P = 0.009) further suggests that FLA are a reservoir for these ARB and underlines the importance of considering amoebae when water control measures are designed.

scholarly journals Identification of Legionella pneumophilaGenes Important for Infection of Amoebas by Signature-Tagged Mutagenesis

2001 ◽  
Vol 69 (2) ◽  
pp. 977-987 ◽  
Author(s):  
Andrea H. Polesky ◽  
Julianna T. D. Ross ◽  
Stanley Falkow ◽  
Lucy S. Tompkins
Keyword(s):  
Legionella Pneumophila ◽  
Mononuclear Cells ◽  
Acanthamoeba Castellanii ◽  
Peripheral Blood Mononuclear ◽  
Vibrio Cholera ◽  
Flagellar Biosynthesis ◽  
Mutant Strains ◽  
Hartmannella Vermiformis ◽  
Different Strains ◽  
Transposon Insertions

ABSTRACT Legionella pneumophila is a facultative intracellular gram-negative rod that causes pneumonia in humans. Free-living amoebas are thought to serve as a reservoir for Legionellainfections. Signature-tagged mutagenesis was employed to identifyLegionella pneumophila genes necessary for survival in the amoeba Acanthamoeba castellanii. Six mutant strains were defective in assays of invasion and intracellular growth. Four mutants also exhibited invasion and replication defects in Hartmannella vermiformis, an amoeba linked to hospital outbreaks ofLegionella pneumonia. The six mutants also were tested in macrophages derived from peripheral blood mononuclear cells. Two mutants had intracellular replication defects, and two different strains entered cells less efficiently. Two transposon insertions were in known L. pneumophila genes, lspK andaroB. The other four were in novel genes. One gene has similarity to a cytochrome c-type biogenesis protein ofPseudomonas fluorescens. Another has similarity to a transcriptional activator regulating flagellar biosynthesis inVibrio cholera. The third is similar to traA ofRhizobium sp. strain NGR234, which is involved in conjugal transfer of DNA. The fourth has no homology. By using survival in amoeba as a selection, we have isolated mutant strains with a range of phenotypes; and we have potentially identified new L. pneumophila virulence genes.

scholarly journals Legionella Pneumophilain a hospital in Torino, Italy A retrospective one-year study.

1989 ◽  
Vol 102 (1) ◽  
pp. 21-30 ◽  
Author(s):  
A. Moiraghi Ruggenini ◽  
M. Castellani Pastoris ◽  
P. J. Dennis ◽  
C. Barral ◽  
A. Sciacovelli ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Tap Water ◽  
Control Measures ◽  
Hospital Environment ◽  
Post Mortem ◽  
Plumbing System ◽  
Water Control ◽  
One Year ◽  
Respiratory Devices

SUMMARYLegionella pneumophilaserogroup 1 was isolated from post mortem specimens from 13 out of 58 patients with pneumonia diagnosed at autopsy. The results of a study undertaken in the hospital environment showed that the water plumbing system was colonized withL. pneumophilaserogroup 1 which could also be isolated from respiratory devices filled with tap water. Control measures instituted are described.

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

Microbiology ◽  
2014 ◽  
Vol 160 (12) ◽  
pp. 2732-2744 ◽  
Author(s):  
Jessica Y. Tyson ◽  
Paloma Vargas ◽  
Nicholas P. Cianciotto
Keyword(s):  
Legionella Pneumophila ◽  
Acanthamoeba Castellanii ◽  
Type Ii Secretion ◽  
The Novel ◽  
Type Ii ◽  
Intracellular Infection ◽  
Novel Proteins ◽  
Hartmannella Vermiformis ◽  
The Individual ◽  
Naegleria Lovaniensis

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.

Impact of inter-amoebic phagocytosis on the L. pneumophila growth

2020 ◽  
Vol 367 (18) ◽  
Author(s):  
Rafik Dey ◽  
Mouh Rayane Mameri ◽  
Selena Trajkovic-Bodennec ◽  
Jacques Bodennec ◽  
Pierre Pernin
Keyword(s):  
Legionella Pneumophila ◽  
Acanthamoeba Castellanii ◽  
Pathogenic Bacterium ◽  
Free Living ◽  
Vermamoeba Vermiformis ◽  
Free Living Amoeba ◽  
Hartmannella Vermiformis ◽  
Freshwater Environments

ABSTRACT Free-living amoebae are known to act as replication niches for the pathogenic bacterium Legionella pneumophila in freshwater environments. However, we previously reported that some strains of the Willaertia magna species are more resistant to L. pneumophila infection and differ in their ability to support its growth. From this observation, we hypothesize that L. pneumophila growth in environment could be partly dependent on the composition of amoebic populations and on the possible interactions between different amoebic species. We tested this hypothesis by studying the growth of L. pneumophila and of a permissive free-living amoeba, Vermamoeba vermiformis (formerly named Hartmannella vermiformis), in co-culture with or without other free-living amoebae (Acanthamoeba castellanii and W. magna). We demonstrate the occurrence of inter-amoebic phagocytosis with A. castellanii and W. magna being able to ingest V. vermiformis infected or not infected with L. pneumophila. We also found that L. pneumophila growth is strongly impacted by the permissiveness of each interactive amoeba demonstrating that L. pneumophila proliferation and spread are controlled, at least in part, by inter-amoebic interactions.

scholarly journals Multiple Legionella pneumophila Type II Secretion Substrates, Including a Novel Protein, Contribute to Differential Infection of the Amoebae Acanthamoeba castellanii, Hartmannella vermiformis, and Naegleria lovaniensis

2013 ◽  
Vol 81 (5) ◽  
pp. 1399-1410 ◽  
Author(s):  
Jessica Y. Tyson ◽  
Meghan M. Pearce ◽  
Paloma Vargas ◽  
Sreya Bagchi ◽  
Brendan J. Mulhern ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Acanthamoeba Castellanii ◽  
Host Cells ◽  
Type Ii Secretion ◽  
Broad Host Range ◽  
Type Ii ◽  
Content Type ◽  
Intracellular Multiplication ◽  
Hartmannella Vermiformis ◽  
Naegleria Lovaniensis

ABSTRACTType II protein secretion (T2S) byLegionella pneumophilais required for intracellular infection of host cells, including macrophages and the amoebaeAcanthamoeba castellaniiandHartmannella vermiformis. Previous proteomic analysis revealed that T2S byL. pneumophila130b mediates the export of >25 proteins, including several that appeared to be novel. Following confirmation that they are unlike known proteins, T2S substrates NttA, NttB, and LegP were targeted for mutation.nttAmutants were impaired for intracellular multiplication inA. castellaniibut notH. vermiformisor macrophages, suggesting that novel exoproteins which are specific toLegionellaare especially important for infection. Because the importance of NttA was host cell dependent, we examined a panel of T2S substrate mutants that had not been tested before in more than one amoeba. As a result, RNase SrnA, acyltransferase PlaC, and metalloprotease ProA all proved to be required for optimal intracellular multiplication inH. vermiformisbut notA. castellanii. Further examination of anlspFmutant lacking the T2S apparatus documented that T2S is also critical for infection of the amoebaNaegleria lovaniensis. Mutants lacking SrnA, PlaC, or ProA, but not those deficient for NttA, were defective inN. lovaniensis. Based upon analysis of a double mutant lacking PlaC and ProA, the role of ProA inH. vermiformiswas connected to its ability to activate PlaC, whereas inN. lovaniensis, ProA appeared to have multiple functions. Together, these data document that the T2S system exports multiple effectors, including a novel one, which contribute in different ways to the broad host range ofL. pneumophila.

Water Quality in the Priority Watercourses of Hong Kong in Respect of Various Environmental Control Measures

1991 ◽  
Vol 23 (1-3) ◽  
pp. 85-91 ◽  
Author(s):  
Ho Kin-chung
Keyword(s):  
Water Quality ◽  
Hong Kong ◽  
Environmental Control ◽  
Control Measures ◽  
Livestock Waste ◽  
Water Control ◽  
Control Zone ◽  
Town Development ◽  
Control Scheme ◽  
Term Monitoring

The water quality in the 12 priority watercourses of Hong Kong was appraised in respect of the various environmental control measures being undertaken. It was noted that water quality in Lam Tsuen River had been significantly improved since 1983. This is attributed to recent resumption of unsewered lands for town development, training of river basin to increase flow, and declaration of the catchment as a “Water Control Zone” under the Water Pollution Control Ordinance. In contrast with the other heavily polluted watercourses to which little abatement measures were implemented, the water qualities of Shing Mun River and Tuen Mun River were slightly upgraded because of the efforts to rectify unauthorized industrial discharges back to foul sewer and provision of interceptors and sewers to villages. The 10 year Livestock Waste Control Scheme enforced on 24 June 1989 was found in parallel with BOD and suspended solids decrease in watercourses. To assess its effectiveness, however, a longer term monitoring is required to get a conclusive result.

scholarly journals A Legionnaires’ Disease Cluster in a Private Building in Italy

2021 ◽  
Vol 18 (13) ◽  
pp. 6922
Author(s):  
Maria Luisa Ricci ◽  
Maria Cristina Rota ◽  
Maria Grazia Caporali ◽  
Antonietta Girolamo ◽  
Maria Scaturro
Keyword(s):  
Severe Pneumonia ◽  
Control Measures ◽  
Health Concern ◽  
Human Consumption ◽  
Domestic Water ◽  
Quality Of Water ◽  
Legionnaires Disease ◽  
Prevention And Control Measures ◽  
Private Homes ◽  
And Control

Legionnaires’ disease (LD) is a severe pneumonia caused by bacteria belonging to the genus Legionella. This is a major public health concern and infections are steadily increasing worldwide. Several sources of infection have been identified, but they have not always been linked to human isolates by molecular match. The well-known Legionella contamination of private homes has rarely been associated with the acquisition of the disease, although some patients never left their homes during the incubation period. This study demonstrated by genomic matching between clinical and environmental Legionella isolates that the source of an LD cluster was a private building. Monoclonal antibodies and sequence-based typing were used to type the isolates, and the results clearly demonstrated the molecular relationship between the strains highlighting the risk of contracting LD at home. To contain this risk, the new European directive on the quality of water intended for human consumption has introduced for the first time Legionella as a microbiological parameter to be investigated in domestic water systems. This should lead to a greater attention to prevention and control measures for domestic Legionella contamination and, consequently, to a possible reduction in community acquired LD cases.

scholarly journals The Interplay between Campylobacter and the Caecal Microbial Community of Commercial Broiler Chickens over Time

2021 ◽  
Vol 9 (2) ◽  
pp. 221
Author(s):  
Ilaria Patuzzi ◽  
Massimiliano Orsini ◽  
Veronica Cibin ◽  
Sara Petrin ◽  
Eleonora Mastrorilli ◽  
...  
Keyword(s):  
Campylobacter Jejuni ◽  
Broiler Chickens ◽  
Control Strategies ◽  
Chicken Meat ◽  
Control Measures ◽  
Microbial Network ◽  
Gut Colonization ◽  
Commercial Broiler ◽  
Zoonotic Bacteria ◽  
Human Infections

Campylobacter is the most frequent foodborne zoonotic bacteria worldwide, with chicken meat being overwhelmingly the most important reservoir for human infections. Control measures implemented at the farm level (i.e., biosecurity or vaccination), which have been successfully applied to limit other pathogens, such as Salmonella, have not been effective in reducing Campylobacter occurrence. Thus, new approaches are needed to fully understand the ecological interactions of Campylobacter with host animals to effectively comprehend its epidemiology. The objective of this study was to analyse longitudinally the gut microbiota composition of Campylobacter-infected and non-infected farms to identify any difference that could potentially be indicative of gut colonization by Campylobacter spp. Differences in the colonization rate and timing were observed at the farms that became positive for Campylobacter jejuni over the investigated time points, even though in positive tests, the occurrence of Campylobacter jejuni gut colonization was not observed before the second week of the life of the birds. Significant differences were observed in the abundances of specific bacterial taxa between the microbiota of individuals belonging to farms that became Campylobacter positive during the study and those who remained negative with particular reference to Bacteroidales and Clostridiales, respectively. Moreover, Campylobacter colonization dramatically influenced the microbiota richness, although to a different extent depending on the infection timing. Finally, a key role of Faecalibacterium and Lactobacillus genera on the Campylobacter microbial network was observed. Understanding the ecology of the Campylobacter interaction with host microbiota during infection could support novel approaches for broiler microbial barrier restoration. Therefore, evidence obtained through this study can be used to identify options to reduce the incidence of infection at a primary production level based on the targeted influence of the intestinal microbiota, thus helping develop new control strategies in order to mitigate the risk of human exposure to Campylobacter by chicken meat consumption.

scholarly journals Development of a Fluorescent Tool for Studying Legionella bozemanae Intracellular Infection

2021 ◽  
Vol 9 (2) ◽  
pp. 379
Author(s):  
Breanne M. Head ◽  
Christopher I. Graham ◽  
Teassa MacMartin ◽  
Yoav Keynan ◽  
Ann Karen C. Brassinga
Keyword(s):  
Growth Kinetics ◽  
Legionella Pneumophila ◽  
Fluorescent Protein ◽  
Disease Incidence ◽  
Acanthamoeba Castellanii ◽  
Infection Model ◽  
Intracellular Infection ◽  
Green Fluorescent

Legionnaires’ disease incidence is on the rise, with the majority of cases attributed to the intracellular pathogen, Legionella pneumophila. Nominally a parasite of protozoa, L. pneumophila can also infect alveolar macrophages when bacteria-laden aerosols enter the lungs of immunocompromised individuals. L. pneumophila pathogenesis has been well characterized; however, little is known about the >25 different Legionella spp. that can cause disease in humans. Here, we report for the first time a study demonstrating the intracellular infection of an L. bozemanae clinical isolate using approaches previously established for L. pneumophila investigations. Specifically, we report on the modification and use of a green fluorescent protein (GFP)-expressing plasmid as a tool to monitor the L. bozemanae presence in the Acanthamoeba castellanii protozoan infection model. As comparative controls, L. pneumophila strains were also transformed with the GFP-expressing plasmid. In vitro and in vivo growth kinetics of the Legionella parental and GFP-expressing strains were conducted followed by confocal microscopy. Results suggest that the metabolic burden imposed by GFP expression did not impact cell viability, as growth kinetics were similar between the GFP-expressing Legionella spp. and their parental strains. This study demonstrates that the use of a GFP-expressing plasmid can serve as a viable approach for investigating Legionella non-pneumophila spp. in real time.

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