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Annals of Clinical Microbiology and... Aug 2017Legionnaires' disease is commonly diagnosed clinically using a urinary antigen test. The urinary antigen test is highly accurate for L. pneumophila serogroup 1, however... (Review)
Review
Legionnaires' disease is commonly diagnosed clinically using a urinary antigen test. The urinary antigen test is highly accurate for L. pneumophila serogroup 1, however other diagnostic tests should also be utilized in conjunction with the urinary antigen as many other Legionella species and serogroups are pathogenic. Culturing of patient specimens remains the gold standard for diagnosis of Legionnaires' disease. Selective media, BYCE with the addition of antibiotics, allows for a high sensitivity and specificity. Culturing can identify all species and serogroups of Legionella. A major benefit of culturing is that it provides the recovery of a patient isolate, which can be used to find an environmental match. Other diagnostic tests, including DFA and molecular tests such as PCR and LAMP, are useful tests to supplement culturing. Molecular tests provide much more rapid results in comparison to culture, however these tests should not be a primary diagnostic tool given their lower sensitivity and specificity in comparison to culturing. It is recommended that all laboratories develop the ability to culture patient specimens in-house with the selective media.
Topics: Antigens, Bacterial; Culture Media; Diagnostic Tests, Routine; Humans; Legionella pneumophila; Legionnaires' Disease; Polymerase Chain Reaction; Respiratory System; Sensitivity and Specificity
PubMed: 28851372
DOI: 10.1186/s12941-017-0229-6 -
Frontiers in Cellular and Infection... 2014The Gram-negative bacterium Legionella pneumophila is ubiquitous in freshwater environments as a free-swimming organism, resident of biofilms, or parasite of protozoa.... (Review)
Review
The Gram-negative bacterium Legionella pneumophila is ubiquitous in freshwater environments as a free-swimming organism, resident of biofilms, or parasite of protozoa. If the bacterium is aerosolized and inhaled by a susceptible human host, it can infect alveolar macrophages and cause a severe pneumonia known as Legionnaires' disease. A sophisticated cell differentiation program equips L. pneumophila to persist in both extracellular and intracellular niches. During its life cycle, L. pneumophila alternates between at least two distinct forms: a transmissive form equipped to infect host cells and evade lysosomal degradation, and a replicative form that multiplies within a phagosomal compartment that it has retooled to its advantage. The efficient changeover between transmissive and replicative states is fundamental to L. pneumophila's fitness as an intracellular pathogen. The transmission and replication programs of L. pneumophila are governed by a number of metabolic cues that signal whether conditions are favorable for replication or instead trigger escape from a spent host. Several lines of experimental evidence gathered over the past decade establish strong links between metabolism, cellular differentiation, and virulence of L. pneumophila. Herein, we focus on current knowledge of the metabolic components employed by intracellular L. pneumophila for cell differentiation, nutrient salvaging and utilization of host factors. Specifically, we highlight the metabolic cues that are coupled to bacterial differentiation, nutrient acquisition systems, and the strategies utilized by L. pneumophila to exploit host metabolites for intracellular replication.
Topics: Environmental Microbiology; Food; Humans; Legionella pneumophila; Legionnaires' Disease; Phagosomes
PubMed: 24575391
DOI: 10.3389/fcimb.2014.00012 -
Sensors (Basel, Switzerland) 2012Bacteria synthesize and sense low molecular weight signaling molecules, termed autoinducers, to measure their population density and community complexity. One class of... (Review)
Review
Bacteria synthesize and sense low molecular weight signaling molecules, termed autoinducers, to measure their population density and community complexity. One class of autoinducers, the α-hydroxyketones (AHKs), is produced and detected by the water-borne opportunistic pathogens Legionella pneumophila and Vibrio cholerae, which cause Legionnaires' disease and cholera, respectively. The "Legionella quorum sensing" (lqs) or "cholera quorum sensing" (cqs) genes encode enzymes that produce and sense the AHK molecules "Legionella autoinducer-1" (LAI-1; 3-hydroxypentadecane-4-one) or cholera autoinducer-1 (CAI-1; 3-hydroxytridecane-4-one). AHK signaling regulates the virulence of L. pneumophila and V. cholerae, pathogen-host cell interactions, formation of biofilms or extracellular filaments, expression of a genomic "fitness island" and competence. Here, we outline the processes, wherein AHK signaling plays a role, and review recent insights into the function of proteins encoded by the lqs and cqs gene clusters. To this end, we will focus on the autoinducer synthases catalysing the biosynthesis of AHKs, on the cognate trans-membrane sensor kinases detecting the signals, and on components of the down-stream phosphorelay cascade that promote the transmission and integration of signaling events regulating gene expression.
Topics: Biofilms; Biosensing Techniques; Cell Communication; Host-Pathogen Interactions; Ketones; Legionella pneumophila; Quorum Sensing; Signal Transduction; Vibrio cholerae
PubMed: 22736983
DOI: 10.3390/s120302899 -
International Journal of Molecular... Oct 2013Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila... (Review)
Review
Legionellosis is mostly caused by Legionella pneumophila and is defined as a severe respiratory illness with a case fatality rate ranging from 5% to 80%. L. pneumophila is ubiquitous in natural and anthropogenic water systems. L. pneumophila is transmitted by inhalation of contaminated aerosols produced by a variety of devices. While L. pneumophila replicates within environmental protozoa, colonization and persistence in its natural environment are also mediated by biofilm formation and colonization within multispecies microbial communities. There is now evidence that some legionellosis outbreaks are correlated with the presence of biofilms. Thus, preventing biofilm formation appears as one of the strategies to reduce water system contamination. However, we lack information about the chemical and biophysical conditions, as well as the molecular mechanisms that allow the production of biofilms by L. pneumophila. Here, we discuss the molecular basis of biofilm formation by L. pneumophila and the roles of other microbial species in L. pneumophila biofilm colonization. In addition, we discuss the protective roles of biofilms against current L. pneumophila sanitation strategies along with the initial data available on the regulation of L. pneumophila biofilm formation.
Topics: Biofilms; Humans; Legionella pneumophila; Legionellosis
PubMed: 24185913
DOI: 10.3390/ijms141121660 -
FEBS Letters Nov 2016The genus Legionella belongs to Gram-negative bacteria found ubiquitously in aquatic habitats, where it grows in natural biofilms and replicates intracellularly in... (Review)
Review
The genus Legionella belongs to Gram-negative bacteria found ubiquitously in aquatic habitats, where it grows in natural biofilms and replicates intracellularly in various protozoa (amoebae, ciliates). L. pneumophila is known as the causative agent of Legionnaires' disease, since it is also able to replicate in human alveolar macrophages, finally leading to inflammation of the lung and pneumonia. To withstand the degradation by its host cells, a Legionella-containing vacuole (LCV) is established for intracellular replication, and numerous effector proteins are secreted into the host cytosol using a type four B secretion system (T4BSS). During intracellular replication, Legionella has a biphasic developmental cycle that alternates between a replicative and a transmissive form. New knowledge about the host-adapted and life stage-dependent metabolism of intracellular L. pneumophila revealed a bipartite metabolic network with life stage-specific usages of amino acids (e.g. serine), carbohydrates (e.g. glucose) and glycerol as major substrates. These metabolic features are associated with the differentiation of the intracellular bacteria, and thus have an important impact on the virulence of L. pneumophila.
Topics: Host-Parasite Interactions; Humans; Legionella pneumophila; Legionnaires' Disease; Metabolic Networks and Pathways; Type IV Secretion Systems; Vacuoles; Virulence
PubMed: 27455397
DOI: 10.1002/1873-3468.12326 -
Annals of Clinical Microbiology and... Mar 2022Legionellosis remains a public health problem. The most common diagnostic method to detect Legionella pneumophila (L. pneumophila) is culture. Polymerase chain reaction... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Legionellosis remains a public health problem. The most common diagnostic method to detect Legionella pneumophila (L. pneumophila) is culture. Polymerase chain reaction (PCR) is a fast and accurate method for this detection in environmental samples.
METHODS
Four databases were searched for studies that evaluated the detection efficiency of PCR in L. pneumophila. The quality evaluation was conducted using Review Manager 5.3. We used Meta-DiSc 1.4 software and the Stata 15.0 software to create forest plots, a meta-regression, a bivariate boxplot and a Deeks' funnel plot.
RESULTS
A total of 18 four-fold tables from 16 studies were analysed. The overall pooled sensitivity and specificity of PCR was 94% and 72%, respectively. The positive likelihood ratio (RLR) and negative likelihood ratio (NLR) was 2.73 and 0.12, respectively. The result of the diagnostic odds ratio (DOR) was 22.85 and the area under the curve (AUC) was 0.7884.
CONCLUSION
Establishing a laboratory diagnostic tool for L. pneumophila detection is important for epidemiological studies. In this work, PCR demonstrated a promising diagnostic accuracy for L. pneumophila.
Topics: Databases, Bibliographic; Environmental Microbiology; Humans; Legionella pneumophila; Odds Ratio; Polymerase Chain Reaction; Sensitivity and Specificity
PubMed: 35303873
DOI: 10.1186/s12941-022-00503-9 -
Frontiers in Cellular and Infection... 2018() is an opportunistic waterborne pathogen and the causative agent for Legionnaires' disease, which is transmitted to humans via inhalation of contaminated water... (Review)
Review
() 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, is able to survive and persist within multi-species biofilms that cover surfaces within water systems. Biofilm formation by 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 in biofilms, even after the extensive chemical and physical treatments. In the microbial consortium-containing among other organisms, several factors either positively or negatively regulate the presence and persistence of in this bacterial community. Biofilm-forming is of a major importance to public health and have impact on the medical and industrial sectors. Indeed, prevention and removal protocols of 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 . In this review, we focus on various factors that contribute to persistence of 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 treatments.
Topics: Biodiversity; Biofilms; Environment; Environmental Microbiology; Factor Analysis, Statistical; Gene Expression Profiling; Iron; Legionella pneumophila; Legionnaires' Disease; Microbial Viability; Quorum Sensing
PubMed: 29535972
DOI: 10.3389/fcimb.2018.00038 -
International Journal of Environmental... Aug 2020The current systematic review investigates the antibiotic susceptibility pattern of isolates from the 1980s to the present day, deriving data from clinical and/or water...
The current systematic review investigates the antibiotic susceptibility pattern of isolates from the 1980s to the present day, deriving data from clinical and/or water samples from studies carried out all over the world. Eighty-nine papers meeting the inclusion criteria, i.e., "" and "resistance to antibiotics", were evaluated according to pre-defined validity criteria. Sixty articles referred to clinical isolates, and 18 articles reported water-related isolates, while 11 articles included both clinical and water isolates. Several methods have been proposed as suitable for the determination of MICs, such as the E-test, broth and agar dilution, and disk diffusion methods, in vivo and in vitro, using various media. The E-test method proposed by the European Society of Clinical Microbiology and Infectious Diseases (EUCAST) seems to be the second most frequently used method overall, but it is the preferred method in the most recent publications (2000-2019) for the interpretation criteria. Erythromycin has been proved to be the preference for resistance testing over the years. However, in the last 19 years, the antibiotics ciprofloxacin (CIP), erythromycin (ERM), levofloxacin (LEV) and azithromycin (AZM) were the ones that saw an increase in their use. A decrease in the sensitivity to antibiotics was identified in approximately half of the reviewed articles.
Topics: Anti-Bacterial Agents; Drug Resistance, Microbial; Erythromycin; Humans; Legionella pneumophila; Legionnaires' Disease; Microbial Sensitivity Tests
PubMed: 32796666
DOI: 10.3390/ijerph17165809 -
Medecine Sciences : M/S 2012Legionella is the causative agent of Legionnaires' disease, a severe form of pneumonia. Detection of Legionella pneumophila serogroup 1 antigen in urine samples has... (Review)
Review
Legionella is the causative agent of Legionnaires' disease, a severe form of pneumonia. Detection of Legionella pneumophila serogroup 1 antigen in urine samples has shortened the delay of diagnosis and subsequent treatment initiation resulting in decreased mortality. Improved surveillance of potable water system reinforces the community prevention. In France, the National Reference Center for Legionella collects the strains responsible for sporadic or epidemic cases and crosslinks the data including epidemiological pattern, clinical presentation, and genetic analysis of the strains. Regarding host-pathogen interactions, major advances have been made recently in the understanding of L. pneumophila ability to subvert the host intracellular trafficking and the innate immune response leading to infection control.
Topics: Host-Pathogen Interactions; Humans; Legionella pneumophila; Legionnaires' Disease; Models, Biological; Population Surveillance
PubMed: 22805141
DOI: 10.1051/medsci/2012286018 -
MBio Oct 2018Within the human host, replicates within alveolar macrophages, leading to pneumonia. However, is an aquatic generalist pathogen that replicates within a wide variety... (Review)
Review
Within the human host, replicates within alveolar macrophages, leading to pneumonia. However, is an aquatic generalist pathogen that replicates within a wide variety of protist hosts, including amoebozoa, percolozoa, and ciliophora. The intracellular lifestyles of within the two evolutionarily distant hosts macrophages and protists are remarkably similar. Coevolution with numerous protist hosts has shaped plasticity of the genome of , which harbors numerous proteins encoded by genes acquired from primitive eukaryotic hosts through interkingdom horizontal gene transfer. The Dot/Icm type IVb translocation system translocates ∼6,000 effectors among species and >320 effector proteins in into host cells to modulate a plethora of cellular processes to create proliferative niches. Since many of the effectors have likely evolved to modulate cellular processes of primitive eukaryotic hosts, it is not surprising that most of the effectors do not contribute to intracellular growth within human macrophages. Some of the effectors may modulate highly conserved eukaryotic processes, while others may target protist-specific processes that are absent in mammals. The lack of studies to determine the role of the effectors in adaptation of to various protists has hampered the progress to determine the function of most of these effectors, which are routinely studied in mouse or human macrophages. Since many protists restrict , utilization of such hosts can also be instrumental in deciphering the mechanisms of failure of to overcome restriction of certain protist hosts. Here, we review the interaction of with its permissive and restrictive protist environmental hosts and outline the accomplishments as well as gaps in our knowledge of -protist host interaction and 's evolution to become a human pathogen.
Topics: Amoebozoa; Biological Coevolution; Ciliophora; Cytoplasm; Genome, Bacterial; Host-Pathogen Interactions; Humans; Legionella pneumophila; Macrophages
PubMed: 30301851
DOI: 10.1128/mBio.01313-18