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1.
J Infect Chemother ; 29(1): 43-47, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36162645

RESUMO

INTRODUCTION: Legionella disease can manifest as severe respiratory tract infection with a high mortality rate and is sometimes associated with a hospital outbreak by a contaminated water supply. A patient with breast cancer admitted about a month before. High fever was observed 18 days after admission and the Legionella antigen test showed the positive result. METHODS: Due to the incidence of Legionella infection, we demonstrated the active surveillance of Legionella contamination in the entire hospital. RESULTS: Cultures of her environmental samples revealed that hot water in two bathrooms were contaminated with Legionella. In our hospital, the hot water is heated and pumped up on the roof and distributed to each room. The contaminated bathrooms were related to the same plumbing. Therefore, we further collected samples throughout the hot water system. Legionella was not detected in the central part of the system. However, we detected Legionella in the hot water sampled from other five rooms, which were also associated with the same plumbing of the two bathrooms. The temperature and chlorine concentration of the hot water were not high enough to inactivate Legionella at the end of the plumbing. After the adjustment of the water temperature and chlorine concentration, Legionella became undetectable. Our prompt and active surveillance successfully identified the plumbing of the hot water system as the source of Legionella contamination and took precautions against future outbreaks. CONCLUSIONS: Monitoring of water temperature and chloride concentration at the end of the hot water circulation is important to prevent nosocomial Legionella disease.


Assuntos
Infecção Hospitalar , Legionella pneumophila , Legionella , Humanos , Cloro , Microbiologia da Água , Abastecimento de Água , Hospitais , Infecção Hospitalar/prevenção & controle , Monitoramento Ambiental , Água
2.
Zhonghua Yu Fang Yi Xue Za Zhi ; 56(11): 1612-1617, 2022 Nov 06.
Artigo em Chinês | MEDLINE | ID: mdl-36372752

RESUMO

Objective: To analyze the pollution status and influencing factors of Legionella pneumophila in a secondary water supply facility in a city. Methods: From June to August 2020, a survey on the level of Legionella pneumophila in secondary water supply unit was carried out in a city in northern China, and 304 sets of secondary water supply facilities were included in the study. A total of 760 water samples were collected from the inlet and outlet water of the secondary water supply facilities and some water samples in the water tank were collected for the detection of Legionella pneumophila, standard plate-count bacteria and related physical and chemical indicators. Through questionnaire survey, the basic information of secondary water supply facilities and daily management of water quality were collected. Multivariate logistic regression model was used to analyze the influencing factors of Legionella pneumophila contamination. Results: Among 304 sets of secondary water supply facilities, most of them were located in residential buildings [57.24% (174/304)]. High and low water tank water supply, low water tank variable frequency conversion water supply and non-negative pressure water supply accounted for 26.6% (81/304), 36.8% (112/304) and 36.5% (111/304), respectively. About 25.7% of facilities (78/304) were positive for Legionella pneumophila. Among them, the positive rates of Legionella pneumophila in high and low water tank water supply, low water tank variable frequency conversion water supply and non-negative pressure water supply facilities were 38.3% (31/81), 29.5% (33/112) and 12.6% (14/111), respectively. The results of multivariate logistic regression model analysis showed that the disinfectant residue could reduce the risk of Legionella pneumophila contamination in water samples, and the OR (95%CI) value was 0.083 (0.022-0.317). The increase of the standard plate-count bacteria and conductivity might increase the risk of Legionella pneumophila contamination in water samples. The OR (95%CI) values were 3.160 (1.667-5.99) and 1.004 (1.001-1.006), respectively. Compared with the non-negative pressure water supply, the risk of Legionella pneumophila contamination of secondary water supply facilities was increased by water supply from high and low water tanks and variable frequency conversion water supply from low water tanks, with OR (95%CI) values of 4.296 (2.096-8.803) and 2.894 (1.449-5.782), respectively. Conclusion: The positive rate of Legionella pneumophila in secondary water supply in the study city is high. Disinfectant residue, conductivity and method of water supply are associated with the positive rate of Legionella pneumophila.


Assuntos
Desinfetantes , Legionella pneumophila , Legionella , Humanos , Microbiologia da Água , Abastecimento de Água , Reprodução
3.
Infect Immun ; 90(11): e0017922, 2022 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-36321832

RESUMO

Legionella pneumophila grows within membrane-bound vacuoles in alveolar macrophages during human disease. Pathogen manipulation of the host cell is driven by bacterial proteins translocated through a type IV secretion system (T4SS). Although host protein synthesis during infection is arrested by the action of several of these translocated effectors, translation of a subset of host proteins predicted to restrict the pathogen is maintained. To identify the spectrum of host proteins selectively synthesized after L. pneumophila challenge, macrophages infected with the pathogen were allowed to incorporate the amino acid analog azidohomoalanine (AHA) during a 2-h time window, and newly synthesized macrophage proteins were isolated by orthogonal chemistry followed by mass spectrometry. Among the proteins isolated were interferon-stimulated genes as well as proteins translated from highly abundant transcripts. Surprisingly, a large number of the identified proteins were from low-abundance transcripts. These proteins were predicted to be among the most efficiently translated per unit transcript in the cell based on ribosome profiling data sets. To determine if high ribosome loading was a consequence of efficient translation initiation, the 5' untranslated regions (5' UTR) of transcripts having the highest and lowest predicted loading levels were inserted upstream of a reporter, and translation efficiency was determined in response to L. pneumophila challenge. The efficiency of reporter expression largely correlated with predicted ribosome loading and lack of secondary structure. Therefore, determinants in the 5' UTR allow selected host cell transcripts to overcome a pathogen-driven translation blockade.


Assuntos
Legionella pneumophila , Humanos , Legionella pneumophila/fisiologia , Regiões 5' não Traduzidas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Interações Hospedeiro-Patógeno/genética , Vacúolos/microbiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo
4.
Virulence ; 13(1): 2042-2058, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36411449

RESUMO

Legionella pneumophila (L.p.) is a bacterial pathogen which is a common causative agent of pneumonia. In humans, it infects alveolar macrophages and transfers hundreds of virulence factors that interfere with cellular signalling pathways and the transcriptomic landscape to sustain its own replication. By this interaction, it has acquired eukaryote-like protein motifs by gene transfer events that partake in the pathogenicity of Legionella. In a computational screening approach for eukaryotic motifs in the transcriptome of Legionella, we identified the L.p. strain Corby protein ABQ55614 as putative histone-deacetylase and named it "suppressing modifier of histones 1" (Smh1). During infection, Smh1 is translocated from the Legionella vacuole into the host cytosol. When expressed in human macrophage THP-1 cells, Smh1 was localized predominantly in the nucleus, leading to broad histone H3 and H4 deacetylation, blunted expression of a large number of genes (e.g. IL-1ß and IL-8), and fostered intracellular bacterial replication. L.p. with a Smh1 knockdown grew normally in media but showed a slight growth defect inside the host cell. Furthermore, Smh1 showed a very potent histone deacetylation activity in vitro, e.g. at H3K14, that could be inhibited by targeted mutation of the putative catalytic center inferred by analogy with eukaryotic HDAC8, and with the deacetylase inhibitor trichostatin A. In summary, Smh1 displays functional homology with class I/II type HDACs. We identified Smh1 as a new Legionella virulence factor with a eukaryote-like histone-deacetylase activity that moderates host gene expression and might pave the way for further histone modifications.IMPORTANCELegionella pneumophila (L.p.) is a prominent bacterial pathogen, which is a common causative agent of pneumonia. In order to survive inside the host cell, the human macrophage, it profoundly interacts with host cell processes to advance its own replication. In this study, we identify a bacterial factor, Smh1, with yet unknown function as a host histone deacetylase. The activity of this factor in the host cell leads to attenuated gene expression and increased intracellular bacterial replication.


Assuntos
Eucariotos , Legionella pneumophila , Humanos , Histonas/genética , Legionella pneumophila/genética , Células Eucarióticas , Pesquisa , Fatores de Virulência/genética , Histona Desacetilases , Proteínas Repressoras
5.
Water Res ; 226: 119238, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36270142

RESUMO

Free-living amoebae are ubiquitous in the environment and cause both opportunistic and non-opportunistic infections in humans. Some genera of amoebae are natural reservoirs of opportunistic plumbing pathogens, such as Legionella pneumophila. In this study, the presence of free-living amoebae and Legionella was investigated in 140 water and biofilm samples collected from Australian domestic (n = 68) and hospital water systems (n = 72). Each sample was screened in parallel using molecular and culture-based methods. Direct quantitative polymerase chain reaction (qPCR) assays showed that 41% samples were positive for Legionella, 33% for L. pneumophila, 11% for Acanthamoeba, and 55% for Vermamoeba vermiformis gene markers. Only 7% of samples contained culturable L. pneumophila serogroup (sg)1, L. pneumophila sg2-14, and non-pneumophila Legionella. In total, 69% of samples were positive for free-living amoebae using any method. Standard culturing found that 41% of the samples were positive for amoeba (either Acanthamoeba, Allovahlkampfia, Stenamoeba, or V. vermiformis). V. vermiformis showed the highest overall frequency of occurrence. Acanthamoeba and V. vermiformis isolates demonstrated high thermotolerance and osmotolerance and strong broad spectrum bacteriogenic activity against Gram-negative and Gram-positive bacteria. Importantly, all Legionella positive samples were also positive for amoeba, and this co-occurrence was statistically significant (p < 0.05). According to qPCR and fluorescence in situ hybridization, V. vermiformis and Allovahlkampfia harboured intracellular L. pneumophila. To our knowledge, this is the first time Allovahlkampfia and Stenamoeba have been demonstrated as hosts of L. pneumophila in potable water. These results demonstrate the importance of amoebae in engineered water systems, both as a pathogen and as a reservoir of Legionella. The high frequency of gymnamoebae detected in this study from Australian engineered water systems identifies an issue of significant public health concern. Future water management protocols should incorporate treatments strategies to control amoebae to reduce the risk to end users.


Assuntos
Acanthamoeba , Amoeba , Água Potável , Legionella pneumophila , Legionella , Humanos , Legionella pneumophila/genética , Microbiologia da Água , Hibridização in Situ Fluorescente , Austrália , Legionella/genética , Água Potável/microbiologia , Acanthamoeba/genética , Hospitais
6.
Infect Immun ; 90(11): e0027622, 2022 11 17.
Artigo em Inglês | MEDLINE | ID: mdl-36314784

RESUMO

The peptidyl-prolyl-cis/trans-isomerase (PPIase) macrophage infectivity potentiator (Mip) contributes to the pathogenicity and fitness of L. pneumophila, the causative agent of Legionnaires' disease. Here, we identified the stringent starvation protein SspB, hypothetical protein Lpc2061, and flagellin FlaA as bacterial interaction partners of Mip. The macrolide FK506, which inhibits the PPIase activity of Mip, interfered with the binding of Lpc2061. Moreover, we demonstrated that the N-terminal dimerization region and amino acid Y185 in the C-terminal PPIase domain of Mip are required for the binding of Lpc2061 and FlaA. The modeling of the interaction partners and global docking with Mip suggested nonoverlapping binding interfaces, and a molecular dynamic simulation predicted an increased stability for the tripartite interaction of Lpc2061, Mip, and FlaA. On the functional level, we demonstrated that Mip promotes L. pneumophila flagellation, which is positively influenced by the binding of Lpc2061 and reduced by FK506. Also, L. pneumophila mutants expressing the Y185A or the monomeric Mip variant, which bind less Lpc2061, were nonmotile, were less flagellated, and yielded less FlaA when quantified. To our knowledge, this is the first report in which a PPIase and its bacterial interaction partners were demonstrated to influence flagellation.


Assuntos
Proteínas de Bactérias , Flagelos , Legionella pneumophila , Macrófagos , Peptidilprolil Isomerase , Humanos , Proteínas de Bactérias/metabolismo , Legionella pneumophila/metabolismo , Doença dos Legionários/microbiologia , Macrófagos/microbiologia , Peptidilprolil Isomerase/metabolismo , Tacrolimo , Flagelos/metabolismo
7.
Can J Microbiol ; 68(12): 747-757, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36194898

RESUMO

Legionella pneumophila is a Gram-negative bacterium found in natural and man-made water systems where it replicates within amoebas and ciliates. In humans, once inside the lungs, L. pneumophila replicates in alveolar macrophages and causes Legionnaires' disease, a severe pneumonia. The Icm/Dot type IVb secretion system is a major virulence factor required for intracellular multiplication. The Icm/Dot system allows the secretion of effectors into the cytoplasm of the host cell. These effectors modify host cell vesicular trafficking and prevent maturation of the phagosome. The innate immune response is crucial in restricting L. pneumophila proliferation. TNF-α is one of the major cytokines involved in this process as it renders macrophages more resistant to L. pneumophila infection and induces apoptosis of L. pneumophila-infected macrophages. Tail-specific proteases (Tsp) are involved in tolerating thermal stress and in virulence. We have previously characterized the Tsp encoded by L. pneumophila, showing that it is important for surviving thermal stress and for infection of amoeba when a temperature change occurs during infection. Here, we demonstrated that Tsp is required for intracellular multiplication in macrophages. Absence of tsp is associated with higher production of TNF-α by macrophages in response to L. pneumophila infection. This effect is independent of the Icm/Dot secretion system.


Assuntos
Legionella pneumophila , Doença dos Legionários , Humanos , Fator de Necrose Tumoral alfa , Doença dos Legionários/microbiologia , Endopeptidases , Proteínas de Bactérias/fisiologia
8.
Emerg Infect Dis ; 28(11): 2357-2360, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36286248

RESUMO

In August 2021, a legionellosis outbreak involving 7 persons occurred within a 500-meter radius in the Montérégie region of Québec, Canada. Near real-time modeling of wind direction along with epidemiologic and environmental investigations identified the possible source. Modeling wind direction could help identify likely Legionella pneumophila sources during legionellosis outbreaks.


Assuntos
Legionella pneumophila , Legionelose , Doença dos Legionários , Humanos , Quebeque/epidemiologia , Legionelose/epidemiologia , Legionella pneumophila/genética , Surtos de Doenças , Canadá , Microbiologia da Água , Doença dos Legionários/epidemiologia
9.
Medicina (Kaunas) ; 58(9)2022 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-36143827

RESUMO

In children, the incidence of Legionnaires' disease (LD) is unknown, hospital-acquired LD is associated with clinical risk factors and environmental risk, and children with cell-mediated immune deficiency are at high risk of infection. Both newborns were born in the same delivery room; stayed in the same hospital room where they were cared for, bathed, and breastfed; were male; were born on time, with normal birth weight, and with high Apgar score at birth; and survived this severe infection (L. pneumophila, serogroup 2-15) but with different clinical courses. In neonate 1, bleeding in the brain, thrombosis of deep pelvic veins, and necrosis of the lungs, which left behind cystic and cavernous changes in the lungs, were found, while neonate 2 suffered from pneumonia alone. The only difference in risk factors for LD between these two newborns is the number of days of illness until the start of azithromycin treatment (sixth versus the third day of illness). We suggest that a change in the guidelines for diagnosing and treating community-acquired pneumonia and hospital-acquired pneumonia in newborns is needed in terms of mandatory routine testing for Legionella pneumophila. Early initiation of macrolide therapy is crucial for the outcome of LD in the newborn.


Assuntos
Infecções Comunitárias Adquiridas , Legionella pneumophila , Doença dos Legionários , Azitromicina/uso terapêutico , Criança , Infecções Comunitárias Adquiridas/diagnóstico , Infecções Comunitárias Adquiridas/tratamento farmacológico , Infecções Comunitárias Adquiridas/epidemiologia , Feminino , Maternidades , Humanos , Recém-Nascido , Doença dos Legionários/diagnóstico , Doença dos Legionários/tratamento farmacológico , Doença dos Legionários/epidemiologia , Masculino , Gravidez
10.
J Water Health ; 20(9): 1393-1404, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36170193

RESUMO

Legionnaires' disease is a serious health risk among the elderly. Water systems in care homes are therefore of particular interest. We investigated the levels of culturable Legionella in the hot water systems in care homes in two Danish municipalities. Two hundred and sixty-eight water samples from 98 care homes were evaluated. Contents of culturable Legionella counts were calculated, and correlations between temperature and colony-forming units (CFU/L) were analysed. Seventy-seven and 81%, respectively, of the care homes were colonised with Legionella in the two municipalities. Most care homes had less than 1,000 CFU/L, but 13 and 16% had more than 10,000 CFU/L. When including first flush samples, 27% of the care homes in Municipality 1 had Legionella levels above 10,000 CFU/L. Temperatures of ≥50 °C in Municipality 1 and ≥55 °C in Municipality 2 correlated with low levels of Legionella. The content of Legionella colonies was significantly higher in care homes in Municipality 1. However, a significantly higher proportion of taps in Municipality 2 had Legionella colonies. In conclusion, temperatures should be raised to 55 °C to avoid high Legionella levels. Test procedures should be evaluated, and the regular use of taps and routine testing for Legionella should be taken into consideration.


Assuntos
Legionella pneumophila , Legionella , Doença dos Legionários , Idoso , Cidades , Dinamarca , Temperatura Alta , Humanos , Água , Microbiologia da Água , Abastecimento de Água
11.
Int J Hyg Environ Health ; 245: 114023, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-36058110

RESUMO

AIM: To observe how Legionella pneumophila, the causative agent for legionellosis, can transmit through the hot water plumbing of residences and office buildings. METHOD AND RESULTS: Using qPCR, L. pneumophila and L. pneumophila Serogroup (Sg)1 were measured in hot water samples collected from 100 structures, consisting of 70 residences and 30 office buildings. The hot water samples collected from office buildings had a higher L. pneumophila detection frequency of 53% (16/30) than residences, with a 103 GU/L (median) concentration. An office building's age was not a statistically significant predictor of contamination, but its area (>100,000 sq. ft.) was, P = <0.001. Hot water samples collected at residences had a lower L. pneumophila detection frequency of 36% (25/70) than office buildings, with a 100 GU/L (median) concentration. A residence's age was a significant predictor of contamination, P = 0.009, but not its area. The water's secondary disinfectant type did not affect L. pneumophila detection frequency nor its concentration in residences, but the secondary disinfectant type did affect results in office buildings. Legionella pneumophila's highest detection frequencies were in samples collected in March-August for office buildings and in June-November for residences. CONCLUSION: This study revealed that the built environment influences L. pneumophila transport and fate. Residential plumbing could be a potential "conduit" for L. pneumophila exposure from a source upstream of the hot water environment. Both old and newly built office buildings had an equal probability of L. pneumophila contamination. Legionella-related remediation efforts in office buildings (that contain commercial functions only) might not significantly improve a community's public health.


Assuntos
Desinfetantes , Legionella pneumophila , Legionella , Engenharia Sanitária , Água , Microbiologia da Água , Abastecimento de Água
12.
Biomed Res Int ; 2022: 4975721, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36164443

RESUMO

Legionella pneumophila is found in the natural aquatic environment and can resist a wide range of environmental conditions. There are around fifty species of Legionella, at least twenty-four of which are directly linked to infections in humans. L. pneumophila is the cause of Legionnaires' disease, a potentially lethal form of pneumonia. By blocking phagosome-lysosome fusion, L. pneumophila lives and proliferates inside macrophages. For this disease, there is presently no authorized multiepitope vaccine available. For the multi-epitope-based vaccine (MEBV), the best antigenic candidates were identified using immunoinformatics and subtractive proteomic techniques. Several immunoinformatics methods were utilized to predict B and T cell epitopes from vaccine candidate proteins. To construct an in silico vaccine, epitopes (07 CTL, 03 HTL, and 07 LBL) were carefully selected and docked with MHC molecules (MHC-I and MHC-II) and human TLR4 molecules. To increase the immunological response, the vaccine was combined with a 50S ribosomal adjuvant. To maximize vaccine protein expression, MEBV was cloned and reverse-translated in Escherichia coli. To prove the MEBV's efficacy, more experimental validation is required. After its development, the resulting vaccine is greatly hoped to aid in the prevention of L. pneumophila infections.


Assuntos
Vacinas Bacterianas , Legionella pneumophila , Doença dos Legionários , Vacinas Bacterianas/genética , Vacinas Bacterianas/imunologia , Epitopos de Linfócito T/imunologia , Humanos , Legionella pneumophila/genética , Legionella pneumophila/imunologia , Doença dos Legionários/prevenção & controle , Proteômica , Receptor 4 Toll-Like/imunologia
13.
Environ Monit Assess ; 194(11): 842, 2022 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-36175694

RESUMO

When a sensitive host inhales aerosols containing these bacteria, Legionella infection occurs. Therefore, monitoring and assessing Legionella in the environment and water distribution systems of such places are critical due to the prone population in hospitals. However, the health risks of Legionella bacteria in the environment are not adequately evaluated. In this study, for hospitalized patients, we performed a quantitative health risk assessment of Legionella in selected hospitals in Tehran city using two scenarios of shower and toilet faucet exposure. This study identified Legionella in 38 cases (38%) out of 100 samples collected from toilet faucets and showers in 8 hospitals. The information gathered was used for quantitative microbial risk assessment (QMRA). The microbial load transmitted by inhalation was calculated using the concentration of Legionella in water. Other exposure parameters (inhalation rate and exposure time) were obtained using information from other studies and the median length of hospital stay (3.6 days). The exponential model was used to estimate the risk of infection (γ = 0.06) due to Legionella pneumophila (L. pneumophila) inhalation for each exposure event. For the mean concentration obtained for Legionella (103 CFU/L), the risk of infection for toilet faucets and showers was in the range of 0.23-2.3 and 3.5-21.9, respectively, per 10,000 hospitalized patients. The results were compared with the tolerable risk level of infection determined by the US EPA and WHO. The risk values exceeded the WHO values for waterborne pathogens in hospitals in both exposure scenarios. As a result, our QMRA results based on monitoring data showed that despite using treated water (from distribution networks in the urban areas) by hospitals, 38% of the samples were contaminated with Legionella, and faucets and showers can be sources of Legionella transmission. Hence, to protect the health of hospitalized patients, the risk of Legionella infection should be considered.


Assuntos
Legionella pneumophila , Monitoramento Ambiental , Hospitais , Humanos , Irã (Geográfico)/epidemiologia , Água
14.
Infect Immun ; 90(10): e0036922, 2022 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-36073935

RESUMO

Previously, we demonstrated that Cas2 encoded within the CRISPR-Cas locus of Legionella pneumophila strain 130b promotes the ability of the Legionella pathogen to infect amoebal hosts. Given that L. pneumophila Cas2 has RNase activity, we posited that the cytoplasmic protein is regulating the expression of another Legionella gene(s) that fosters intracellular infection. Proteomics revealed 10 proteins at diminished levels in the cas2 mutant, and reverse transcription-quantitative (qRT-PCR) confirmed the reduced expression of a gene encoding putative small heat shock protein C2 (HspC2), among several others. As predicted, the gene was expressed more highly at 37°C to 50°C than that at 30°C, and an hspC2 mutant, but not its complemented derivative, displayed ~100-fold reduced CFU following heat shock at 55°C. Compatible with the effect of Cas2 on hspC2 expression, strains lacking Cas2 also had impaired thermal tolerance. The hspC2 mutant, like the cas2 mutant before it, was greatly impaired for infection of Acanthamoeba castellanii, a frequent host for legionellae in waters. HspC2 and Cas2 were not required for entry into these host cells but promoted the replicative phase of intracellular infection. Finally, the hspC2 mutant exhibited an additional defect during the infection of macrophages, which are the primary host for legionellae during lung infection. In summary, hspC2 is upregulated by the presence of Cas2, and HspC2 uniquely promotes both L. pneumophila extracellular survival at high temperatures and infection of amoebal and human host cells. To our knowledge, these findings also represent the first genetic proof linking Cas2 to thermotolerance, expanding the repertoire of noncanonical functions associated with CRISPR-Cas proteins.


Assuntos
Acanthamoeba castellanii , Proteínas de Choque Térmico Pequenas , Legionella pneumophila , Humanos , Legionella pneumophila/fisiologia , Proteínas de Choque Térmico Pequenas/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Ribonucleases/metabolismo
15.
Environ Sci Pollut Res Int ; 29(51): 76532-76542, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36161570

RESUMO

An increase in the number of reports of legionellosis in the European Union and the European Economic Area have been recorded in recent years. The increase in cases is significant: from 6947 reports in 2015 to 11,298 in 2019. This is alarming as genus Legionella, which comprises a large group of bacteria inhabiting various aquatic systems, poses a serious threat to human health and life, since more than 20 species can cause legionellosis, with L. pneumophila being responsible for the majority of cases. The ability to colonize diverse ecosystems makes the eradication of these microorganisms difficult. A detailed understanding of the Legionella habitat may be helpful in the effective control of this pathogen. This paper provides an overview of Legionella environments in Europe: natural (lakes, groundwater, rivers, compost, soil) and anthropogenic (fountains, air humidifiers, water supply systems), and the role of Legionella spp. in nosocomial infections, which are potentially fatal for children, the elderly and immunocompromised patients.


Assuntos
Legionella pneumophila , Legionella , Legionelose , Criança , Humanos , Idoso , Ecossistema , Microbiologia da Água , Legionelose/etiologia , Legionelose/microbiologia , Europa (Continente) , Solo
16.
Acta Crystallogr D Struct Biol ; 78(Pt 9): 1110-1119, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36048151

RESUMO

The pathogen Legionella pneumophila, which is the causative agent of Legionnaires' disease, secrets hundreds of effectors into host cells via its Dot/Icm secretion system to subvert host-cell pathways during pathogenesis. VipF, a conserved core effector among Legionella species, is a putative acetyltransferase, but its structure and catalytic mechanism remain unknown. Here, three crystal structures of VipF in complex with its cofactor acetyl-CoA and/or a substrate are reported. The two GNAT-like domains of VipF are connected as two wings by two ß-strands to form a U-shape. Both domains bind acetyl-CoA or CoA, but only in the C-terminal domain does the molecule extend to the bottom of the U-shaped groove as required for an active transferase reaction; the molecule in the N-terminal domain folds back on itself. Interestingly, when chloramphenicol, a putative substrate, binds in the pocket of the central U-shaped groove adjacent to the N-terminal domain, VipF remains in an open conformation. Moreover, mutations in the central U-shaped groove, including Glu129 and Asp251, largely impaired the acetyltransferase activity of VipF, suggesting a unique enzymatic mechanism for the Legionella effector VipF.


Assuntos
Legionella pneumophila , Legionella , Doença dos Legionários , Acetilcoenzima A/metabolismo , Acetilação , Acetiltransferases , Proteínas de Bactérias/química , Legionella/metabolismo , Legionella pneumophila/química , Legionella pneumophila/genética , Legionella pneumophila/metabolismo , Doença dos Legionários/genética
17.
Environ Sci Technol ; 56(16): 11363-11373, 2022 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-35929739

RESUMO

Legionella growth in healthcare building water systems can result in legionellosis, making water management programs (WMPs) important for patient safety. However, knowledge is limited on Legionella prevalence in healthcare buildings. A dataset of quarterly water testing in Veterans Health Administration (VHA) healthcare buildings was used to examine national environmental Legionella prevalence from 2015 to 2018. Bayesian hierarchical logistic regression modeling assessed factors influencing Legionella positivity. The master dataset included 201,146 water samples from 814 buildings at 168 VHA campuses. Overall Legionella positivity over the 4 years decreased from 7.2 to 5.1%, with the odds of a Legionella-positive sample being 0.94 (0.90-0.97) times the odds of a positive sample in the previous quarter for the 16 quarters of the 4 year period. Positivity varied considerably more at the medical center campus level compared to regional levels or to the building level where controls are typically applied. We found higher odds of Legionella detection in older buildings (OR 0.92 [0.86-0.98] for each more recent decade of construction), in taller buildings (OR 1.20 [1.13-1.27] for each additional floor), in hot water samples (O.R. 1.21 [1.16-1.27]), and in samples with lower residual biocide concentrations. This comprehensive healthcare building review showed reduced Legionella detection in the VHA healthcare system over time. Insights into factors associated with Legionella positivity provide information for healthcare systems implementing WMPs and for organizations setting standards and regulations.


Assuntos
Legionella pneumophila , Legionella , Doença dos Legionários , Idoso , Teorema de Bayes , Atenção à Saúde , Monitoramento Ambiental , Humanos , Doença dos Legionários/epidemiologia , Água , Microbiologia da Água , Abastecimento de Água
18.
PLoS Pathog ; 18(8): e1010720, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35951533

RESUMO

Bacterial type IV secretion systems (T4SSs) are a versatile group of nanomachines that can horizontally transfer DNA through conjugation and deliver effector proteins into a wide range of target cells. The components of T4SSs in gram-negative bacteria are organized into several large subassemblies: an inner membrane complex, an outer membrane core complex, and, in some species, an extracellular pilus. Cryo-electron tomography has been used to define the structures of T4SSs in intact bacteria, and high-resolution structural models are now available for isolated core complexes from conjugation systems, the Xanthomonas citri T4SS, the Helicobacter pylori Cag T4SS, and the Legionella pneumophila Dot/Icm T4SS. In this review, we compare the molecular architectures of these T4SSs, focusing especially on the structures of core complexes. We discuss structural features that are shared by multiple T4SSs as well as evolutionary strategies used for T4SS diversification. Finally, we discuss how structural variations among T4SSs may confer specialized functional properties.


Assuntos
Helicobacter pylori , Legionella pneumophila , Proteínas de Bactérias/metabolismo , Sistemas de Secreção Bacterianos/metabolismo , Tomografia com Microscopia Eletrônica , Helicobacter pylori/metabolismo , Legionella pneumophila/metabolismo , Sistemas de Secreção Tipo IV/genética
19.
Microbiol Spectr ; 10(4): e0221022, 2022 08 31.
Artigo em Inglês | MEDLINE | ID: mdl-35950853

RESUMO

The engulfment of Legionella pneumophila by free-living amoebae (FLA) in engineered water systems (EWS) enhances L. pneumophila persistence and provides a vehicle for rapid replication and increased public health risk. Despite numerous legionellosis outbreaks worldwide, effective tools for studying interactions between L. pneumophila and FLA in EWS are lacking. To address this, we have developed a biopolymer surrogate with a similar size, shape, surface charge, and hydrophobicity to those of stationary-phase L. pneumophila. Parallel experiments were conducted to observe the engulfment of L. pneumophila and the surrogate by Acanthamoeba polyphaga in dechlorinated, filter-sterilised tap water at 30°C for 72 h. Trophozoites engulfed both the surrogate and L. pneumophila, reaching maximum uptake after 2 and 6 h, respectively, but the peak surrogate uptake was ~2-log lower. Expulsion of the engulfed surrogate from A. polyphaga was also faster compared to that of L. pneumophila. Confocal laser scanning microscopy confirmed that the surrogate was actively engulfed and maintained within vacuoles for several hours before being expelled. L. pneumophila and surrogate phagocytosis appear to follow similar pathways, suggesting that the surrogate can be developed as a useful tool for studying interactions between L. pneumophila and FLA in EWS. IMPORTANCE The internalization of L. pneumophila within amoebae is a critical component of their life cycle in EWS, as it protects the bacteria from commonly used water disinfectants and provides a niche for their replication. Intracellularly replicated forms of L. pneumophila are also more virulent and resistant to sanitizers. Most importantly, the bacteria's adaptation to the intracellular environments of amoebae primes them for the infection of human macrophages, posing a significant public health risk in EWS. The significance of our study is that a newly developed L. pneumophila biopolymer surrogate can mimic the L. pneumophila engulfment process in A. polyphaga, a free-living amoeba. With further development, the surrogate has the potential to improve the understanding of amoeba-mediated L. pneumophila persistence in EWS and the associated public health risk management.


Assuntos
Acanthamoeba , Legionella pneumophila , Acanthamoeba/microbiologia , Alginatos , Biopolímeros , Carbonato de Cálcio , DNA , Humanos , Legionella pneumophila/genética , Água
20.
J Appl Microbiol ; 133(6): 3596-3604, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36000381

RESUMO

AIMS: Legionella pneumophila (Lp), a human pathogen, has been detected in windscreen wiper fluid reservoirs (WWFRs) where commercial screen washes (CSWs) are commonly added. Limited information is available on CSWs against planktonic Lp; however, responses of sessile Lp and planktonic Lp pre-acclimated in nutrient-limited water to CSWs remain unknown. This study thus investigates the antibacterial effects of CSWs on sessile and starved planktonic Lp, in comparison with unstarved Lp. METHODS AND RESULTS: Lp biofilms were produced on glass and WWFR materials of high-density polyethylene (HDPE) and polypropylene (PP). Planktonic Lp with and without acclimation in tap water were prepared. Log reductions in cell counts averaged 0.4-5.0 for 10 brands of CSWs against sessile Lp and 1.0-3.9 and 0.9-4.9, respectively, against starved and unstarved planktonic Lp for five CSWs. Both biofilm formation and acclimation in tap water enhanced Lp resistance to CSWs. Significantly different log-reduction values among CSW brands were observed for sessile Lp on HDPE and planktonic Lp regardless of acclimation (p < 0.05). CONCLUSIONS: Biofilm formation, starvation acclimation and CSW brand are crucial factors influencing Lp response to CSWs. SIGNIFICANCE AND IMPACT OF STUDY: This study advances the knowledge of Lp reaction in anthropogenic water systems with CSWs.


Assuntos
Anti-Infecciosos , Legionella pneumophila , Humanos , Automóveis , Polietileno , Biofilmes , Plâncton , Água/farmacologia , Anti-Infecciosos/farmacologia , Microbiologia da Água
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