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La Revue de Medecine Interne Dec 2019Legionella-related disease is caused by an intracellular bacteria mainly living in water. Contamination results from inhalation of Legionella sp containing aerosolized... (Review)
Review
Legionella-related disease is caused by an intracellular bacteria mainly living in water. Contamination results from inhalation of Legionella sp containing aerosolized water. Main risk factors are tobacco, immunodeficiency, and advanced age. Antigenuria is the cornerstone of the diagnosis. Immunocompromised patients, more commonly infected with non pneumophilaLegionella, present negative antigenuria, and culture and PCR are essential for the diagnosis. Legionnaires' disease may be severe, especially in elderly and/or immunocompromised patients. Mortality rate varies from 10 % in the general population to 50 % in intensive care. Treatment is based on macrolides or fluoroquinolones. Antibiotic resistance is very rare.
Topics: Aged; Anti-Bacterial Agents; Diagnosis, Differential; Disease Outbreaks; Humans; Immunocompromised Host; Legionella; Legionellosis; Legionnaires' Disease; Polymerase Chain Reaction; Risk Factors
PubMed: 31703951
DOI: 10.1016/j.revmed.2019.08.007 -
Current Environmental Health Reports Mar 2022
Topics: Disease Outbreaks; Humans; Legionnaires' Disease
PubMed: 34003468
DOI: 10.1007/s40572-021-00319-3 -
Journal of Clinical Medicine Oct 2022An outbreak of a potentially fatal form of pneumonia in 1976 and in the annual convention of the American Legion was the first time that spp. was identified.... (Review)
Review
An outbreak of a potentially fatal form of pneumonia in 1976 and in the annual convention of the American Legion was the first time that spp. was identified. Thereafter, the term Legionnaires' disease (LD) was established. The infection in humans is transmitted by the inhalation of aerosols that contain the microorganisms that belong to the Legionellaceae family and the genus Legionella. The genus Legionella contains genetically heterogeneous species and serogroups. The serogroup 1 (Lp1) is the most often detected strain in outbreaks of LD. The pathogenesis of LD infection initiates with the attachment of the bacterial cells to the host cells, and subsequent intracellular replication. Following invasion, spp. activates its virulence mechanisms: generation of specific compartments of Legionella-containing vacuole (LCV), and expression of genes that encode a type IV secretion system (T4SS) for the translocation of proteins. The ability of to transmigrate across the lung's epithelium barrier leads to bacteremia, spread, and invasion of many organs with subsequent manifestations, complications, and septic shock. The clinical manifestations of LD depend on the bacterial load in the aerosol, the virulence factors, and the immune status of the patient. The infection has two distinct forms: the non- pneumatic form or Pontiac fever, which is a milder febrile flu-like illness, and LD, a more severe form, which includes pneumonia. In addition, the extrapulmonary involvement of LD can include heart, brain, abdomen, and joints.
PubMed: 36294446
DOI: 10.3390/jcm11206126 -
Cellular Microbiology Oct 2020Intracellular bacterial pathogens harbour genes, the closest homologues of which are found in eukaryotes. Regulator of chromosome condensation 1 (RCC1) repeat proteins... (Review)
Review
Intracellular bacterial pathogens harbour genes, the closest homologues of which are found in eukaryotes. Regulator of chromosome condensation 1 (RCC1) repeat proteins are phylogenetically widespread and implicated in protein-protein interactions, such as the activation of the small GTPase Ran by its cognate guanine nucleotide exchange factor, RCC1. Legionella pneumophila and Coxiella burnetii, the causative agents of Legionnaires' disease and Q fever, respectively, harbour RCC1 repeat coding genes. Legionella pneumophila secretes the RCC1 repeat 'effector' proteins LegG1, PpgA and PieG into eukaryotic host cells, where they promote the activation of the pleiotropic small GTPase Ran, microtubule stabilisation, pathogen vacuole motility and intracellular bacterial growth as well as host cell migration. The RCC1 repeat effectors localise to the pathogen vacuole or the host plasma membrane and target distinct components of the Ran GTPase cycle, including Ran modulators and the small GTPase itself. Coxiella burnetii translocates the RCC1 repeat effector NopA into host cells, where the protein localises to nucleoli. NopA binds to Ran GTPase and promotes the nuclear accumulation of Ran(GTP), thus pertubing the import of the transcription factor NF-κB and innate immune signalling. Hence, divergent evolution of bacterial RCC1 repeat effectors defines the range of Ran GTPase cycle targets and likely allows fine-tuning of Ran GTPase activation by the pathogens at different cellular sites.
Topics: Animals; Bacterial Proteins; Biological Evolution; Cell Nucleolus; Coxiella burnetii; Enzyme Activation; Genes, Bacterial; Guanine Nucleotide Exchange Factors; Host-Pathogen Interactions; Humans; Legionella; Legionella pneumophila; Legionnaires' Disease; Protein Transport; Q Fever; Vacuoles; ran GTP-Binding Protein
PubMed: 32720355
DOI: 10.1111/cmi.13246 -
Internal Medicine (Tokyo, Japan) Jan 2021Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential...
Legionellosis is a serious bacterial infection characterized by atypical pneumonia primarily due to infection with Legionella pneumophila, and bathing can be a potential cause of this infection. Legionellosis was first identified in 1977, and it is caused by Gram-negative bacteria belonging to the genus Legionella. Legionellosis remains an important public health threat, particularly in Japan, where the population is rapidly aging, thereby becoming more at risk of developing severe disease and accompanying life-threatening pneumonia. The bacteria are most commonly transmitted via the inhalation of contaminated aerosols produced and broadcast via water sprays, jets or mists. Infection can also occur via the aspiration of contaminated water or ice, or through inhalation of contaminated dust. Because the signs and symptoms of Legionnaires' disease (LD), as well as radiographic imaging are similar to pneumonia caused by other pathogens, a specific diagnostic test is required, such as a urine antigen detection test. Six clinical and laboratory parameters, a high body temperature, a non-productive cough, low serum sodium and platelet counts, and high lactate dehydrogenase (LDH) and c-reactive protein concentrations can be used to reliably predict the likelihood of LD. The first choices for chemotherapy are fluoroquinolone and macrolide antibiotic drugs. The main goals of LD prevention measures are 1) the prevention of microbial growth and biofilm formation, 2) the removal of all biofilm formed on equipment and in facilities, 3) minimizing aerosol splash and spread, and 4) minimizing bacterial contamination from external sources. It is apparent that, in Japan, where hot spring (onsen) bathing is common among aged people, strict regulations need to be in place - and enforced - to ensure that all Japanese onsens and spas provide a safe environment and undertake regular, effective infection control practices.
Topics: Aged; Humans; Japan; Legionella; Legionella pneumophila; Legionellosis; Legionnaires' Disease; Water Microbiology
PubMed: 32727982
DOI: 10.2169/internalmedicine.4852-20 -
Microorganisms Jan 2021Although known as causes of community-acquired pneumonia and Pontiac fever, the global burden of infection caused by species other than is under-recognised. Non-... (Review)
Review
Although known as causes of community-acquired pneumonia and Pontiac fever, the global burden of infection caused by species other than is under-recognised. Non- legionellae have a worldwide distribution, although common testing strategies for legionellosis favour detection of over other species, leading to an inherent diagnostic bias and under-detection of cases. When systematically tested for in Australia and New Zealand, was shown to be a leading cause of community-acquired pneumonia. Exposure to potting soils and compost is a particular risk for infection from , and may be better adapted to soil and composting plant material than other species. It is possible that the high rate of reported in Australia and New Zealand is related to the composition of commercial potting soils which, unlike European products, contain pine bark and sawdust. Genetic studies have demonstrated that the genomes are highly plastic, with areas of the chromosome showing high levels of recombination as well as horizontal gene transfer both within and between species via plasmids. This, combined with various secretion systems and extensive effector repertoires that enable the bacterium to hijack host cell functions and resources, is instrumental in shaping its pathogenesis, survival and growth. Prevention of legionellosis is hampered by surveillance systems that are compromised by ascertainment bias, which limits commitment to an effective public health response. Current prevention strategies in Australia and New Zealand are directed at individual gardeners who use potting soils and compost. This consists of advice to avoid aerosols generated by the use of potting soils and use masks and gloves, but there is little evidence that this is effective. There is a need to better understand the epidemiology of and other species in order to develop effective treatment and preventative strategies globally.
PubMed: 33572638
DOI: 10.3390/microorganisms9020291 -
Cureus Apr 2023Legionnaires' disease is caused by a potentially life-threatening infection with the opportunistic Gram-negative bacilli species , which is transmitted via inhalation or...
Legionnaires' disease is caused by a potentially life-threatening infection with the opportunistic Gram-negative bacilli species , which is transmitted via inhalation or aspiration of water droplets. Legionnaires' commonly presents as atypical community-acquired pneumonia with accompanying diarrhea. Although hepatic and renal involvement are relatively uncommon, in this report, we present a case of pneumonia with acute hepatitis.
PubMed: 37187646
DOI: 10.7759/cureus.37497 -
Proceedings of the National Academy of... Jun 2023Peptidoglycan is a critical component of the bacteria cell envelope. Remodeling of the peptidoglycan is required for numerous essential cellular processes and has been...
Peptidoglycan is a critical component of the bacteria cell envelope. Remodeling of the peptidoglycan is required for numerous essential cellular processes and has been linked to bacterial pathogenesis. Peptidoglycan deacetylases that remove the acetyl group of the -acetylglucosamine (NAG) subunit protect bacterial pathogens from immune recognition and digestive enzymes secreted at the site of infection. However, the full extent of this modification on bacterial physiology and pathogenesis is not known. Here, we identify a polysaccharide deacetylase of the intracellular bacterial pathogen and define a two-tiered role for this enzyme in pathogenesis. First, NAG deacetylation is important for the proper localization and function of the Type IVb secretion system, linking peptidoglycan editing to the modulation of host cellular processes through the action of secreted virulence factors. As a consequence, the vacuole mis-traffics along the endocytic pathway to the lysosome, preventing the formation of a replication permissive compartment. Second, within the lysosome, the inability to deacetylate the peptidoglycan renders the bacteria more sensitive to lysozyme-mediated degradation, resulting in increased bacterial death. Thus, the ability to deacetylate NAG is important for bacteria to persist within host cells and in turn, virulence. Collectively, these results expand the function of peptidoglycan deacetylases in bacteria, linking peptidoglycan editing, Type IV secretion, and the intracellular fate of a bacterial pathogen.
Topics: Humans; Legionella pneumophila; Peptidoglycan; Vacuoles; Legionella; Lysosomes; Bacterial Proteins; Legionnaires' Disease
PubMed: 37252954
DOI: 10.1073/pnas.2119658120 -
Cureus Dec 2022We report the case of a woman from the Bronx, New York, who presented to the emergency department (ED) in June 2020 with a febrile respiratory illness resembling...
We report the case of a woman from the Bronx, New York, who presented to the emergency department (ED) in June 2020 with a febrile respiratory illness resembling coronavirus disease 2019 (COVID-19) but was ultimately diagnosed with Legionnaires' disease (LD). New York City (NYC) rapidly became an epicenter of the global COVID-19 pandemic in 2020. In the years since the pandemic started, variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have recurred in multiple waves and remain an important cause of viral respiratory illness. The bacteria is often under-recognized as a cause of community-acquired pneumonia, yet it recurs each year in clusters, outbreaks, or as sporadic infections. Pneumonia caused by SARS-CoV-2 and can present similarly and may not be readily distinguished in the absence of diagnostic testing.
PubMed: 36605056
DOI: 10.7759/cureus.32169 -
Frontiers in Microbiology 2023is an opportunistic intracellular pathogen that inhabits artificial water systems and can be transmitted to human hosts by contaminated aerosols. Upon inhalation, it... (Review)
Review
is an opportunistic intracellular pathogen that inhabits artificial water systems and can be transmitted to human hosts by contaminated aerosols. Upon inhalation, it colonizes and grows inside the alveolar macrophages and causes Legionnaires' disease. To effectively control and manage Legionnaires' disease, a deep understanding of the host-pathogen interaction is crucial. Bacterial extracellular vesicles, particularly outer membrane vesicles (OMVs) have emerged as mediators of intercellular communication between bacteria and host cells. These OMVs carry a diverse cargo, including proteins, toxins, virulence factors, and nucleic acids. OMVs play a pivotal role in disease pathogenesis by helping bacteria in colonization, delivering virulence factors into host cells, and modulating host immune responses. This review highlights the role of OMVs in the context of host-pathogen interaction shedding light on the pathogenesis of . Understanding the functions of OMVs and their cargo provides valuable insights into potential therapeutic targets and interventions for combating Legionnaires' disease.
PubMed: 37817751
DOI: 10.3389/fmicb.2023.1270123