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1.
MMWR Morb Mortal Wkly Rep ; 69(8): 207-211, 2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32106217

RESUMO

In January 2018, the Wisconsin Department of Health Services, Division of Public Health (DPH), received a report of a culture-confirmed case of Legionnaires' disease. The patient, who was immunocompromised, had died at a local hospital 10 days after being admitted. DPH and an infection preventionist from the hospital investigated to determine the source of the infection and prevent additional cases. Because the case was suspected to be nosocomial, health care facility water samples were tested for Legionella. When these samples were negative, water sources in the patient's home were tested. These tested positive for Legionella pneumophila, and the bacteria remained after an attempt to remediate. The patient and home isolates were identified as L. pneumophila serogroup 3, sequence type 93, by whole-genome multilocus sequence typing. A second resident of the home did not become ill. This case highlights the potential for immunocompromised persons and others at risk for Legionnaires' disease to be exposed to Legionella through home water systems containing the bacteria and demonstrates the difficulty of home remediation. This case also illustrates the role of lower respiratory tract specimens in the identification of less common Legionella infections (e.g., L. pneumophila serogroup 3) and confirmation of the infection source.


Assuntos
Exposição Ambiental/efeitos adversos , Habitação , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/diagnóstico , Idoso , Evolução Fatal , Humanos , Legionella pneumophila/classificação , Sorotipagem , Wisconsin
2.
mBio ; 11(1)2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31992628

RESUMO

The intracellular pathogen Legionella pneumophila utilizes the Icm/Dot type IV secretion system to translocate >300 effector proteins into host cells during infection. The regulation of some of these effector-encoding genes was previously shown to be coordinated by several global regulators, including three two-component systems (TCSs) found in all the Legionella species examined. Here, we describe the first Legionella genomic island encoding a single Icm/Dot effector and a dedicated TCS, which regulates its expression. This genomic island, which we named Lci, undergoes horizontal gene transfer in the Legionella genus, and the TCS encoded from this island (LciRS) is homologous to TCSs that control the expression of various metal resistance systems found in other bacteria. We found that the L. pneumophila sensor histidine kinase LciS is specifically activated by copper via a unique, small periplasmic sensing domain. Upon activation by LciS, the response regulator LciR directly binds to a conserved regulatory element and activates the expression of the adjacently located lciE effector-encoding gene. Thus, LciR represents the first local regulator of effectors identified in L. pneumophila Moreover, we found that the expression of the lciRS operon is repressed by the Fis1 and Fis3 regulators, leading to Fis-mediated effects on copper induction of LciE and silencing of the expression of this genomic island in the absence of copper. This island represents a novel type of effector regulation in Legionella, shedding new light on the ways by which the Legionella pathogenesis system evolves its effector repertoire and expands its activating signals.IMPORTANCE Legionella pneumophila is an intracellular human pathogen that utilizes amoebae as its environmental host. The adaptation of L. pneumophila to the intracellular environment requires coordination of expression of its multicomponent pathogenesis system, which is composed of a secretion system and effector proteins. However, the regulatory factors controlling the expression of this pathogenesis system are only partially uncovered. Here, we discovered a novel regulatory system that is activated by copper and controls the expression of a single effector protein. The genes encoding both the regulatory system and the effector protein are located on a genomic island that undergoes horizontal gene transfer within the Legionella genus. This regulator-effector genomic island represents the first reported case of local regulation of effectors in Legionella The discovery of this regulatory mechanism is an important step forward in the understanding of how the regulatory network of effectors functions and evolves in the Legionella genus.


Assuntos
Proteínas de Bactérias/genética , Cobre/metabolismo , Regulação Bacteriana da Expressão Gênica , Genoma Bacteriano , Ilhas Genômicas , Legionella/genética , Legionella/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Ordem dos Genes , Transferência Genética Horizontal , Legionella/classificação , Legionella pneumophila/classificação , Legionella pneumophila/genética , Legionella pneumophila/metabolismo , Filogenia , Ligação Proteica , Transcrição Genética
3.
Lett Appl Microbiol ; 70(4): 232-240, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31904109

RESUMO

Unregulated private wells are understudied potential sources of community-acquired Legionnaires' disease. Here we conducted a comprehensive survey of 44 homes supplied by private wells in Wake County, North Carolina, quantifying Legionella spp. DNA, Legionella pneumophila DNA, and total bacterial 16S rRNA genes via real-time polymerase chain reaction in hot and cold drinking water samples, along with culturable L. pneumophila via IDEXX Legiolert in cold drinking water samples. Legionella spp. DNA, L. pneumophila DNA and culturable L. pneumophila were detected in 100, 65·5 and 15·9% of the 44 homes, respectively, and culturable levels were comparable to some municipal surveys applying the same methods. Total coliforms and Escherichia coli were monitored as representative faecal indicators and were found in 20·4 and 0·0% of homes. Within certain sample types, Legionella spp. and L. pneumophila gene copy numbers were positively associated with total bacteria (i.e. total 16S rRNA genes) and water softener use, but were not associated with faecal indicator bacteria, inorganic water parameters or other well characteristics. These findings confirm that occurrence of Legionella and L. pneumophila is highly variable in private wells. SIGNIFICANCE AND IMPACT OF THE STUDY: Legionella is the leading identified cause of waterborne disease outbreaks associated with US municipal water systems. While Legionella is known to occur naturally in groundwater, prior efforts to characterize its occurrence in unregulated private wells are limited to sampling at the wellhead and not in the home plumbing where Legionella can thrive. This work documents much higher levels of Legionella in home plumbing versus water directly from private wells and examines factors associated with higher Legionella occurrence.


Assuntos
Água Potável/microbiologia , Legionella pneumophila/isolamento & purificação , DNA Bacteriano/genética , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Doença dos Legionários/microbiologia , North Carolina , RNA Ribossômico 16S/genética , Engenharia Sanitária , Microbiologia da Água , Abastecimento de Água
4.
Int J Infect Dis ; 91: 174-176, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31707135

RESUMO

Three cases of pneumonia caused by Legionella pneumophila serogroup 1 (Lp1) in immunosuppressed patients with repeated hospitalization were suspected as a healthcare-associated cluster. The environmental investigation did not reveal the presence of legionellae in the hospital patient rooms. Water samples collected from the homes of two patients were also negative for Legionella spp. In the absence of environmental strains potentially involved in the infections, we proceeded to genotype environmental Lp1 strains isolated in the hospital during routine water sampling during the decade 2009-2019 and recovered after long-term storage at -20°C. These 'historical' strains exhibited a high grade of similarity and stability over time, regardless of the disinfection systems. The different molecular profiles shown among the clinical and environmental strains excluded a nosocomial outbreak. The study suggests that the application of molecular typing may be a useful tool to discriminate hospital vs community-acquired cases, mostly for severely immunosuppressed patients in whom the symptomatology could be insidious and the incubation period could be prolonged. Moreover, the genotyping allowed us to exclude any link between the cases.


Assuntos
Técnicas de Genotipagem , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/microbiologia , Idoso , Idoso de 80 Anos ou mais , Infecção Hospitalar/microbiologia , Surtos de Doenças , Feminino , Humanos , Imunossupressão , Legionella pneumophila/classificação , Legionella pneumophila/genética , Doença dos Legionários/epidemiologia , Doença dos Legionários/terapia , Masculino , Pessoa de Meia-Idade , Tipagem Molecular , Sorogrupo
5.
Emerg Infect Dis ; 25(11): 2013-2020, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31625848

RESUMO

During the water crisis in Flint, Michigan, USA (2014-2015), 2 outbreaks of Legionnaires' disease occurred in Genesee County, Michigan. We compared whole-genome sequences of 10 clinical Legionella pneumophila isolates submitted to a laboratory in Genesee County during the second outbreak with 103 water isolates collected the following year. We documented a genetically diverse range of L. pneumophila strains across clinical and water isolates. Isolates belonging to 1 clade (3 clinical isolates, 3 water isolates from a Flint hospital, 1 water isolate from a Flint residence, and the reference Paris strain) had a high degree of similarity (2-1,062 single-nucleotide polymorphisms), all L. pneumophila sequence type 1, serogroup 1. Serogroup 6 isolates belonging to sequence type 2518 were widespread in Flint hospital water samples but bore no resemblance to available clinical isolates. L. pneumophila strains in Flint tap water after the outbreaks were diverse and similar to some disease-causing strains.


Assuntos
Água Potável/microbiologia , Genoma Bacteriano , Legionella pneumophila/genética , Doença dos Legionários/epidemiologia , Doença dos Legionários/microbiologia , Microbiologia da Água , Sequenciamento Completo do Genoma , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/isolamento & purificação , Michigan/epidemiologia , Filogenia , Polimorfismo de Nucleotídeo Único
6.
Emerg Infect Dis ; 25(11): 2104-2107, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31625866

RESUMO

Legionellosis was diagnosed in an immunocompromised 3-year-old girl in Canada. We traced the source of the bacterium through co-culture with an ameba collected from a hot tub in her home. We identified Legionella pneumophila serogroup 6, sequence type 185, and used whole-genome sequencing to confirm the environmental and clinical isolates were of common origin.


Assuntos
Amoeba/microbiologia , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/epidemiologia , Doença dos Legionários/microbiologia , Canadá/epidemiologia , Técnicas de Cocultura , Surtos de Doenças , Genoma Bacteriano , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Filogenia , Vigilância em Saúde Pública , Sequenciamento Completo do Genoma
7.
Emerg Infect Dis ; 25(6): 1218-1219, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31107214

RESUMO

We report national surveillance of Legionnaires' disease in China. Urine samples from 11 (3.85%) of 286 patients with severe pneumonia of unknown cause were positive for the Legionella pneumophila serogroup 1 antigen. We isolated Legionella strains from 7 patients. Improved diagnostic testing is needed for this underestimated disease in China.


Assuntos
Legionella pneumophila , Doença dos Legionários/epidemiologia , Doença dos Legionários/microbiologia , Adulto , Idoso , Antígenos de Bactérias/imunologia , China/epidemiologia , Feminino , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/efeitos dos fármacos , Legionella pneumophila/genética , Legionella pneumophila/imunologia , Doença dos Legionários/diagnóstico , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Tipagem Molecular , Vigilância em Saúde Pública , Sorogrupo , Adulto Jovem
8.
mSphere ; 4(1)2019 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-30814318

RESUMO

Between 2000 and 2017, a total of 236 Legionella species isolates from Arizona were submitted to the CDC for reference testing. Most of these isolates were recovered from bronchoalveolar lavage specimens. Although the incidence of legionellosis in Arizona is less than the overall U.S. incidence, Arizona submits the largest number of isolates to the CDC for testing compared to those from other states. In addition to a higher proportion of culture confirmation of legionellosis cases in Arizona than in other states, all Legionella pneumophila isolates are forwarded to the CDC for confirmatory testing. Compared to that from other states, a higher proportion of isolates from Arizona were identified as belonging to L. pneumophila serogroups 6 (28.2%) and 8 (8.9%). Genome sequencing was conducted on 113 L. pneumophila clinical isolates not known to be associated with outbreaks in order to understand the genomic diversity of strains causing legionellosis in Arizona. Whole-genome multilocus sequence typing (wgMLST) revealed 17 clusters of isolates sharing at least 99% identical allele content. Only two of these clusters contained isolates from more than one individual with exposure at the same facility. Additionally, wgMLST analysis revealed a group of 31 isolates predominantly belonging to serogroup 6 and containing isolates from three separate clusters. Single nucleotide polymorphism (SNP) and pangenome analysis were used to further resolve genome sequences belonging to a subset of isolates. This study demonstrates that culture of clinical specimens for Legionella spp. reveals a highly diverse population of strains causing legionellosis in Arizona which could be underappreciated using other diagnostic approaches.IMPORTANCE Culture of clinical specimens from patients with Legionnaires' disease is rarely performed, restricting our understanding of the diversity and ecology of Legionella Culture of Legionella from patient specimens in Arizona revealed a greater proportion of non-serogroup 1 Legionella pneumophila isolates than in other U.S. isolates examined. Disease caused by such isolates may go undetected using other diagnostic methods. Moreover, genome sequence analysis revealed that these isolates were genetically diverse, and understanding these populations may help in future environmental source attribution studies.


Assuntos
Variação Genética , Genoma Bacteriano , Legionella pneumophila/classificação , Doença dos Legionários/microbiologia , Arizona/epidemiologia , Técnicas de Tipagem Bacteriana , Centers for Disease Control and Prevention, U.S. , Genótipo , Humanos , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/epidemiologia , Tipagem de Sequências Multilocus , Sorogrupo , Estados Unidos , Sequenciamento Completo do Genoma
9.
Epidemiol Infect ; 146(16): 2116-2121, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30157982

RESUMO

Legionella pneumophila genotyping is important for epidemiological investigation of nosocomial and community-acquired outbreaks of legionellosis. The prevalence of legionellosis in pneumonia patients in the West Bank was monitored for the first time, and the sequence types (STs) from respiratory samples were compared with STs of environmental samples from different wards of the hospital. Sputum (n = 121) and bronchoalveolar lavage (BAL) (n = 74) specimens were cultured for L. pneumophila; genomic DNA was tested by 16S rRNA polymerase chain reaction (PCR) amplification. Nested PCR sequence-based typing (NPSBT) was implemented on DNA of the respiratory and environmental PCR-positive samples. Only one respiratory specimen was positive for L. pneumophila by culture. BAL gave a higher percentage of L. pneumophila-positive samples, 35% (26/74) than sputum, 15% (18/121) by PCR. NPSBT revealed the following STs: ST 1 (29%, 7/24), ST 461 (21%, 5/24), ST 1037 (4%, 1/24) from respiratory samples, STs from environmental samples: ST 1 (28.5%, 4/14), ST 187 (21.4%, 3/14) and ST 2070, ST 461, ST 1482 (7.1%, 1/14) each. This study emphasises the advantage of PCR over culture for the detection of L. pneumophila in countries where antibiotics are indiscriminately used prior to hospital admission. ST 1 was the predominant ST in both respiratory and environmental samples.


Assuntos
Secreções Corporais/microbiologia , Microbiologia Ambiental , Legionella pneumophila/classificação , Legionella pneumophila/genética , Doença dos Legionários/microbiologia , Tipagem de Sequências Multilocus/métodos , Sistema Respiratório/microbiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Líquido da Lavagem Broncoalveolar/microbiologia , Criança , Pré-Escolar , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Feminino , Genótipo , Hospitais , Humanos , Lactente , Legionella pneumophila/isolamento & purificação , Masculino , Pessoa de Meia-Idade , Oriente Médio , Reação em Cadeia da Polimerase , Prevalência , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Escarro/microbiologia , Adulto Jovem
10.
BMC Microbiol ; 18(1): 75, 2018 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-30016940

RESUMO

BACKGROUND: Legionella pneumophila, the causative agent of Legionnaire's disease, may enter a viable but non-culturable (VBNC) state triggered by environmental stress conditions. Specific outer-membrane epitopes of L. pneumophila are used in many diagnostic applications and some of them are linked to important virulence-related factors or endotoxins. However, it is not clear how the presence and status of these epitopes are influenced by environmental stress conditions. In this study, changes of outer membrane epitopes for monoclonal antibodies (mAb) from the Dresden panel and the major outer membrane protein MOMP were analysed for five L. pneumophila strains during short- and long-term starvation in ultrapure water. RESULTS: With ELISA and single cell immuno-fluorescence analysis, we could show that for most of the investigated mAb-strain combinations the total number of mAb-stained Legionella cells stayed constant for up to 400 days. Especially the epitopes of mAb 3/1, 8/5, 26/1 and 20/1, which are specific for L. pneumophila serogroup 1 subtypes, and the mAb 9/1, specific for serogroup 6, showed long-term persistence. For most mAb- stained cells, a high percentage of viable cells was observed at least until 118 days of starvation. At the same time, we observed a reduction of the fluorescence intensity of the stained cells during starvation indicating a loss of epitopes from the cell surface. However, most of the epitopes, including the virulence-associated mAb 3/1 epitope were still present with high fluorescence intensity after 400 days of starvation in up to 50% of the starved L. pneumophila population. CONCLUSIONS: The results demonstrate the continuous presence of outer membrane epitopes of L. pneumophila during short-term and long-term starvation. Thus, culture-independent mAb-based diagnostic and detection tools, such as immuno-magnetic separation and microarray techniques are applicable for both L. pneumophila in the culturable and the VBNC state even after long-term starvation but nevertheless require careful testing before application. However, the mere presence of those epitopes is not necessarily an indication of viability or infectivity.


Assuntos
Membrana Celular/imunologia , Epitopos/imunologia , Legionella pneumophila/crescimento & desenvolvimento , Legionella pneumophila/imunologia , Anticorpos Antibacterianos/imunologia , Anticorpos Monoclonais/imunologia , Ensaio de Imunoadsorção Enzimática , Imunofluorescência , Legionella pneumophila/classificação , Viabilidade Microbiana , Sorogrupo , Estresse Fisiológico , Fatores de Virulência/imunologia
11.
Curr Microbiol ; 75(10): 1282-1289, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29980812

RESUMO

Legiolert® is a new culture method for quantification of Legionella pneumophila, which is the primary species associated with Legionnaires' disease. The test is based on a most probable number approach, and differs significantly from traditional culture methods by providing results at 7 days, rapid sample preparation and analysis, and objective interpretation of test results. In this study, we compared the performance of Legiolert with the U.S. Centers for Disease Control and Prevention (CDC) method for detection of L. pneumophila from non-potable samples, primarily comprising cooling tower waters. Our results demonstrated no significant difference between Legiolert and the CDC method for quantification of L. pneumophila. However, Legiolert showed a significant increase in sensitivity when water samples containing higher L. pneumophila concentrations were examined. Cooling tower waters often contain non-Legionella organisms (NLO) that interfere with traditional Legionella test methods, and we observed varying degrees of NLO interference on many CDC method plates. In contrast, Legiolert was resistant to NLO interference and produced a very low rate of false-positive results. Collectively, Legiolert is a sensitive and specific method for quantification of L. pneumophila from non-potable water that provides advantages over the CDC method.


Assuntos
Técnicas Bacteriológicas/métodos , Água Doce/microbiologia , Legionella pneumophila/isolamento & purificação , Centers for Disease Control and Prevention, U.S. , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Doença dos Legionários/microbiologia , Sensibilidade e Especificidade , Estados Unidos , Abastecimento de Água
12.
J Appl Microbiol ; 125(4): 1216-1225, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29802665

RESUMO

AIMS: A molecular method for a rapid detection of viable Legionella pneumophila of all serogroups in tap water samples was developed as an alternative to the reference method (ISO). Legionellae are responsible for Legionnaires' disease, a severe pneumonia in humans with high lethality. METHODS AND RESULTS: The developed method is based on a nutritional stimulation and detection of an increase in precursor 16S rRNA as an indicator for viability. For quantification, DNA was detected by qPCR. This method was compared to the ISO method using water samples obtained from public sports facilities in Switzerland. The sensitivity and specificity were 91 and 97%, respectively, when testing samples for compliance with a microbiological criterion of 1000 cell equivalents per l. CONCLUSION: The new method is sensitive and specific for Leg. pneumophila and allows results to be obtained within 8 h upon arrival, compared to one week or more by the ISO method. SIGNIFICANCE AND IMPACT OF THE STUDY: The method represents a useful tool for a rapid detection of viable Leg. pneumophila of all serogroups in water by molecular biology. It can be used as an alternative to the ISO method for official water analysis for legionellae and particularly when a short test time is required.


Assuntos
Água Doce/microbiologia , Legionella pneumophila/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , DNA Bacteriano/genética , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Legionella pneumophila/crescimento & desenvolvimento , Doença dos Legionários/microbiologia , Viabilidade Microbiana , RNA Ribossômico 16S/genética , Sensibilidade e Especificidade , Microbiologia da Água
13.
Artigo em Inglês | MEDLINE | ID: mdl-29670859

RESUMO

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.


Assuntos
Legionella pneumophila/patogenicidade , Doença dos Legionários/microbiologia , Mariposas/microbiologia , Animais , Modelos Animais de Doenças , Microbiologia Ambiental , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Legionella pneumophila/isolamento & purificação , Filogenia , Virulência
14.
FEMS Microbiol Lett ; 365(10)2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29566231

RESUMO

Legionella pneumophila (Lp) is ubiquitous in the aquatic environment and can persist within drinking water distribution systems (DWDS) enabling these systems to serve as a potential source of human infections. Bacterial surface charge, deduced from electrophoretic mobility (EPM), is a well-recognized contributor to microorganism mobility, adherence and interactions with their surrounding environment. In this study, the EPM of 32 Lp strains representing serogroup (sg) 1 to 14 were measured, in 9.15 mM KH2PO4 at pH 8, to understand cell surface properties that may influence their occurrence within DWDS. EPM measurements indicated the charge of Lp varied widely between serogroups with five distinct clusters, from least to most negatively charged: (i) sg1 to 3, 5, and 12; (ii) sg6, 8, and 10; (iii) sg9 and 13; (iv) sg7, 11, and 14; and (v) sg4. The EPM of sg1 and 4 strains were pH dependent; however, values were constant between pH 6 and 9, a range typical of drinking water, suggesting that EPM differences between Lp serogroups could impact their survival within DWDS. Understanding the ecological importance of Lp surface properties (e.g. in mobility, colonization, resistance to disinfectants, etc.) within DWDS would aid in mitigation of health risks associated with this water-based pathogen.


Assuntos
Eletroforese/métodos , Legionella pneumophila/química , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/microbiologia , Sorotipagem/métodos , Humanos , Legionella pneumophila/classificação , Filogenia , Sorogrupo , Microbiologia da Água
15.
Appl Environ Microbiol ; 84(10)2018 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-29523542

RESUMO

Legionella pneumophila causes water-based infections resulting in severe pneumonia. Recently, we showed that different MLVA-8 (multilocus variable-number tandem-repeat analysis using 8 loci) genotypes dominated different sites of a drinking-water distribution system. Each genotype displayed a unique temperature-dependent growth behavior. Here we compared the pathogenicity potentials of different MLVA-8 genotypes of environmental and clinical strains. The virulence traits studied were hemolytic activity and cytotoxicity toward amoebae and macrophages. Clinical strains were significantly more hemolytic than environmental strains, while their cytotoxicity toward amoebae was significantly lower at 30°C. No significant differences were detected between clinical and environmental strains in cytotoxicity toward macrophages. Significant differences in virulence were observed between the environmental genotypes (Gt). Gt15 strains showed a significantly higher hemolytic activity. In contrast, Gt4 and Gt6 strains were more infective toward Acanthamoeba castellanii Moreover, Gt4 strains exhibited increased cytotoxicity toward macrophages and demonstrated a broader temperature range of amoebal lysis than Gt6 and Gt15 strains. Understanding the virulence traits of Legionella genotypes may improve the assessment of public health risks of Legionella in drinking water.IMPORTANCELegionella pneumophila is the causative agent of a severe form of pneumonia. Here we demonstrated that clinical strains were significantly more cytotoxic toward red blood cells than environmental strains, while their cytotoxicity toward macrophages was similar. Genotype 4 (Gt4) strains were highly cytotoxic toward amoebae and macrophages and lysed amoebae in a broader temperature range than to the other studied genotypes. The results can explain the relatively high success of Gt4 in the environment and in clinical samples; thus, Gt4 strains should be considered a main factor for the assessment of public health risks of Legionella in drinking water. Our findings shed light on the ecology, virulence, and pathogenicity potential of different L. pneumophila genotypes, which can be a valuable parameter for future modeling and quantitative microbial risk assessment of Legionella in drinking-water systems.


Assuntos
Água Potável/microbiologia , Legionella pneumophila/genética , Legionella pneumophila/patogenicidade , Doença dos Legionários/microbiologia , Repetições Minissatélites , Amoeba/microbiologia , Microbiologia Ambiental , Genótipo , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/isolamento & purificação , Macrófagos/microbiologia , Tipagem de Sequências Multilocus , Fenótipo , Filogenia , Virulência
16.
Am J Infect Control ; 46(8): 943-945, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29502885

RESUMO

In a tertiary hospital, Legionella spp were isolated from taps and from ward dishwashers connected to contaminated tap piping. Our investigation revealed favorable conditions for growth of Legionella, and showed that Legionella pneumophila SG6 isolates from the taps and dishwashers were all genetically identical by repetitive-element polymerase chain reaction. These results suggest that contaminated dishwashers might be a potential reservoir for the spread of Legionella in health care facilities.


Assuntos
Microbiologia Ambiental , Contaminação de Equipamentos , Serviço Hospitalar de Limpeza/métodos , Legionella pneumophila/isolamento & purificação , Genótipo , Humanos , Legionella pneumophila/classificação , Legionella pneumophila/genética , Tipagem Molecular , Centros de Atenção Terciária
17.
Artigo em Inglês | MEDLINE | ID: mdl-29535972

RESUMO

Legionella pneumophila (L. pneumophila) is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water droplets. The bacterium is able to colonize a variety of man-made water systems such as cooling towers, spas, and dental lines and is widely distributed in multiple niches, including several species of protozoa In addition to survival in planktonic phase, L. pneumophila is able to survive and persist within multi-species biofilms that cover surfaces within water systems. Biofilm formation by L. pneumophila is advantageous for the pathogen as it leads to persistence, spread, resistance to treatments and an increase in virulence of this bacterium. Furthermore, Legionellosis outbreaks have been associated with the presence of L. pneumophila in biofilms, even after the extensive chemical and physical treatments. In the microbial consortium-containing L. pneumophila among other organisms, several factors either positively or negatively regulate the presence and persistence of L. pneumophila in this bacterial community. Biofilm-forming L. pneumophila is of a major importance to public health and have impact on the medical and industrial sectors. Indeed, prevention and removal protocols of L. pneumophila as well as diagnosis and hospitalization of patients infected with this bacteria cost governments billions of dollars. Therefore, understanding the biological and environmental factors that contribute to persistence and physiological adaptation in biofilms can be detrimental to eradicate and prevent the transmission of L. pneumophila. In this review, we focus on various factors that contribute to persistence of L. pneumophila within the biofilm consortium, the advantages that the bacteria gain from surviving in biofilms, genes and gene regulation during biofilm formation and finally challenges related to biofilm resistance to biocides and anti-Legionella treatments.


Assuntos
Biofilmes , Microbiologia Ambiental , Legionella pneumophila/fisiologia , Biodiversidade , Meio Ambiente , Análise Fatorial , Perfilação da Expressão Gênica , Ferro/metabolismo , Legionella pneumophila/classificação , Doença dos Legionários/metabolismo , Doença dos Legionários/microbiologia , Viabilidade Microbiana , Percepção de Quorum
18.
Artigo em Inglês | MEDLINE | ID: mdl-29587446

RESUMO

Several Travel-associated Legionnaires' disease (TALD) cases occur annually in Europe. Except from the most obvious sites (cooling towers and hot water systems), infections can also be associated with recreational, water feature, and garden areas of hotels. This argument is of great interest to better comprehend the colonization and to calculate the risk to human health of these sites. From July 2000-November 2017, the public health authorities of the Island of Crete (Greece) inspected 119 hotels associated with TALD, as reported through the European Legionnaires' Disease Surveillance Network. Five hundred and eighteen samples were collected from decorative fountain ponds, showers near pools and spas, swimming pools, spa pools, garden sprinklers, drip irrigation systems (reclaimed water) and soil. Of those, 67 (12.93%), originating from 43 (35.83%) hotels, tested positive for Legionella (Legionella pneumophila serogroups 1, 2, 3, 6, 7, 8, 13, 14, 15 and non-pneumophila species (L. anisa, L. erythra, L. taurinensis, L. birminghamensis, L. rubrilucens). A Relative Risk (R.R.) > 1 (p < 0.0001) was calculated for chlorine concentrations of less than 0.2 mg/L (R.R.: 54.78), star classification (<4) (R.R.: 4.75) and absence of Water Safety Plan implementation (R.R.: 3.96). High risk (≥104 CFU/L) was estimated for pool showers (16.42%), garden sprinklers (7.46%) and pool water (5.97%).


Assuntos
Jardins , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/epidemiologia , Piscinas , Microbiologia da Água , Monitoramento Ambiental , Grécia/epidemiologia , Humanos , Legionella pneumophila/classificação , Recreação , Medição de Risco , Doença Relacionada a Viagens
19.
mBio ; 9(1)2018 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-29437918

RESUMO

Coinciding with major changes to its municipal water system, Flint, MI, endured Legionnaires' disease outbreaks in 2014 and 2015. By sampling premise plumbing in Flint in the fall of 2016, we found that 12% of homes harbored legionellae, a frequency similar to that in residences in neighboring areas. To evaluate the genetic diversity of Legionella pneumophila in Southeast Michigan, we determined the sequence type (ST) and serogroup (SG) of the 18 residential isolates from Flint and Detroit, MI, and the 33 clinical isolates submitted by hospitals in three area counties in 2013 to 2016. Common to one environmental and four clinical samples were strains of L. pneumophila SG1 and ST1, the most prevalent ST worldwide. Among the Flint premise plumbing isolates, 14 of 16 strains were of ST367 and ST461, two closely related SG6 strain types isolated previously from patients and corresponding environmental samples. Each of the representative SG1 clinical strains and SG6 environmental isolates from Southeast Michigan infected and survived within macrophage cultures at least as well as a virulent laboratory strain, as judged by microscopy and by enumerating CFU. Likewise, 72 h after infection, the yield of viable-cell counts increased >100-fold for each of the representative SG1 clinical isolates, Flint premise plumbing SG6 ST367 and -461 isolates, and two Detroit residential isolates. We verified by immunostaining that SG1-specific antibody does not cross-react with the SG6 L. pneumophila environmental strains. Because the widely used urinary antigen diagnostic test does not readily detect non-SG1 L. pneumophila, Legionnaires' disease caused by SG6 L. pneumophila is likely underreported worldwide.IMPORTANCEL. pneumophila is the leading cause of disease outbreaks associated with drinking water in the United States. Compared to what is known of the established risks of colonization within hospitals and hotels, relatively little is known about residential exposure to L. pneumophila One year after two outbreaks of Legionnaires' disease in Genesee County, MI, that coincided with damage to the Flint municipal water system, our multidisciplinary team launched an environmental surveillance and laboratory research campaign aimed at informing risk management strategies to provide safe public water supplies. The most prevalent L. pneumophila strains isolated from residential plumbing were closely related strains of SG6. In laboratory tests of virulence, the SG6 environmental isolates resembled SG1 clinical strains, yet they are not readily detected by the common diagnostic urinary antigen test, which is specific for SG1. Therefore, our study complements the existing epidemiological literature indicating that Legionnaires' disease due to non-SG1 strains is underreported around the globe.


Assuntos
Água Potável/microbiologia , Variação Genética , Legionella pneumophila/classificação , Legionella pneumophila/isolamento & purificação , Legionelose/microbiologia , Engenharia Sanitária , Sorogrupo , Humanos , Legionella pneumophila/genética , Macrófagos/microbiologia , Michigan , Viabilidade Microbiana , Tipagem de Sequências Multilocus , Prevalência
20.
Epidemiol Infect ; 146(3): 297-302, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29386076

RESUMO

A large outbreak of Legionnaires' disease occurred at a California state prison in August 2015. We conducted environmental and epidemiological investigations to identify the most likely source of exposure and characterise morbidity. Sixty-four inmates had probable Legionnaires' disease; 14 had laboratory-confirmed legionellosis. Thirteen (17%) inmates were hospitalised; there were no deaths. Ill inmates were more likely to be ⩾65 years old (P < 0.01), have the chronic obstructive pulmonary disease (P < 0.01), diabetes mellitus (P = 0.02), hepatitis C infection (P < 0.01), or end-stage liver disease (P < 0.01). The case-patients were in ten housing units throughout the prison grounds. All either resided in or were near the central clinical building (for appointments or yard time) during their incubation periods. Legionella pneumophila serogroup 1 was cultured from three cooling towers on top of the central medical clinic (range, 880-1200 cfu/ml). An inadequate water management program, dense biofilm within the cooling towers, and high ambient temperatures preceding the outbreak created an ideal environment for Legionella sp. proliferation. All state prisons were directed to develop local operating procedures for maintaining their cooling towers and the state health department added a review of the maintenance plans to their environmental inspection protocol.


Assuntos
Surtos de Doenças , Legionella pneumophila/isolamento & purificação , Doença dos Legionários/epidemiologia , Prisões , Microbiologia da Água , Adulto , Idoso , Idoso de 80 Anos ou mais , California/epidemiologia , Humanos , Legionella/classificação , Legionella/isolamento & purificação , Legionella pneumophila/classificação , Legionelose/epidemiologia , Legionelose/microbiologia , Doença dos Legionários/microbiologia , Pessoa de Meia-Idade , Fatores de Risco , Abastecimento de Água
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