Legionellaceae
Legionella
Legionnaires' Disease
Sequencing of the rpoB gene in Legionella pneumophila and characterization of mutations associated with rifampin resistance in the Legionellaceae. (1/9)
Rifampin in combination with erythromycin is a recommended treatment for severe cases of legionellosis. Mutations in the rpoB gene are known to cause rifampin resistance in Escherichia coli and Mycobacterium tuberculosis, and the purpose of the present study was to investigate a possible similar resistance mechanism within the members of the family Legionellaceae. Since the RNA polymerase genes of this genus have never been characterized, the DNA sequence of the Legionella pneumophila rpoB gene was determined by the Vectorette technique for genome walking. A 4,647-bp DNA sequence that contained the open reading frame (ORF) of the rpoB gene (4,104 bp) and an ORF of 384 bp representing part of the rpoC gene was obtained. A 316-bp DNA fragment in the center of the L. pneumophila rpoB gene, corresponding to a previously described site for mutations leading to rifampin resistance in M. tuberculosis, was sequenced from 18 rifampin-resistant Legionella isolates representing four species (L. bozemanii, L. longbeachae, L. micdadei, and L. pneumophila), and the sequences were compared to the sequences of the fragments from the parent (rifampin-sensitive) strains. Six single-base mutations which led to amino acid substitutions at five different positions were identified. A single strain did not contain any mutations in the 316-bp fragment. This study represents the characterization of a hitherto undescribed resistance mechanism within the family Legionellaceae. (+info)Presence of Legionellaceae in warm water supplies and typing of strains by polymerase chain reaction. (2/9)
Outbreaks of Legionnaire's disease present a public health challenge especially because fatal outcomes still remain frequent. The aim of this study was to describe the abundance and epidemiology of Legionellaceae in the human-made environment. Water was sampled from hot-water taps in private and public buildings across the area of Gottingen, Germany, including distant suburbs. Following isolation, we used polymerase chain reaction in order to generate strain specific banding profiles of legionella isolates. In total, 70 buildings were examined. Of these 18 (26%) had the bacterium in at least one water sample. Legionella pneumophila serogroups 1, 4, 5 and 6 could be identified in the water samples. Most of the buildings were colonized solely by one distinct strain, as proven by PCR. In three cases equal patterns were found in separate buildings. There were two buildings in this study where isolates with different serogroups were found at the same time. (+info)Characterization of members of the Legionellaceae family by automated ribotyping. (3/9)
In order to implement a new and reliable method for characterizing different species of Legionella, a genetic fingerprinting study with an automated ribotyping system (RiboPrinter) was completed with members of this genus which were deposited at the American Type Culture Collection. The RiboPrinter examined the different patterns of EcoRI digestion fragments from the rRNA operons of 110 strains, representing 48 of the 49 described Legionella species as well as 70 serogroups of those species. Distinctive and consistent patterns were obtained for the type strains of the 48 species investigated. Legionella pneumophila subsp. fraseri and L. pneumophila subsp. pascullei each generated a specific pattern, whereas L. pneumophila subsp. pneumophila produced six different fingerprint patterns. No correlation seemed to exist between the ribotypes obtained and the 15 serotypes of L. pneumophila. For the other species, those with two known serogroups presented two distinctive patterns with the RiboPrinter with the exception of L. hackeliae and L. quinlivanii, which yielded only one pattern. We also encountered ribotypes for strains which were not identified to the species level. The ribotypes generated for these strains with the RiboPrinter did not match those generated for known type strains, suggesting the putative description of new serogroups or species. Although the automated system did not have sufficient discriminatory ability to serve as an epidemiological tool in a clinical setting, it appeared to be a powerful tool for general genomic analysis of the Legionella isolates (e.g., determination of new species) and assessment of the interrelationship among Legionella strains through the RiboPrinter database connection. (+info)Virulence factors of the family Legionellaceae. (4/9)
Whereas bacteria in the genus Legionella have emerged as relatively frequent causes of pneumonia, the mechanisms underlying their pathogenicity are obscure. The legionellae are facultative intracellular pathogens which multiply within the phagosome of mononuclear phagocytes and are not killed efficiently by polymorphonuclear leukocytes. The functional defects that might permit the intracellular survival of the legionellae have remained an enigma until recently. Phagosome-lysosome fusion is inhibited by a single strain (Philadelphia 1) of Legionella pneumophila serogroup 1, but not by other strains of L. pneumophila or other species. It has been found that following the ingestion of Legionella organisms, the subsequent activation of neutrophils and monocytes in response to both soluble and particulate stimuli is profoundly impaired and the bactericidal activity of these cells is attenuated, suggesting that Legionella bacterial cell-associated factors have an inhibitory effect on phagocyte activation. Two factors elaborated by the legionellae which inhibit phagocyte activation have been described. First, the Legionella (cyto)toxin blocks neutrophil oxidative metabolism in response to various agonists by an unknown mechanism. Second, L. micdadei bacterial cells contain a phosphatase which blocks superoxide anion production by stimulated neutrophils. The Legionella phosphatase disrupts the formation of critical intracellular second messengers in neutrophils. In addition to the toxin and phosphatase, several other moieties that may serve as virulence factors by promoting cell invasion or intracellular survival and multiplication are elaborated by the legionellae. Molecular biological studies show that a cell surface protein named Mip is necessary for the efficient invasion of monocytes. A possible role for a Legionella phospholipase C as a virulence factor is still largely theoretical. L. micdadei contains an unusual protein kinase which catalyzes the phosphorylation of eukaryotic substrates, including phosphatidylinositol and tubulin. Since the phosphorylation of either phosphatidylinositol or tubulin might compromise phagocyte activation and bactericidal functions, this enzyme may well be a virulence factor. Administration of the L. pneumophila exoprotease induces lesions resembling those of Legionella pneumonia and kills guinea pigs, suggesting that this protein plays a role in the pathogenesis of legionellosis. However, recent work with a genetically engineered strain has convincingly shown that the protease is not necessary for intracellular survival or virulence. As might be expected with a complex process like intracellular parasitism, it appears that the capability of Legionella strains to invade and multiply in host phagocytes is multifactorial and that no single moiety which is responsible for the virulence phenotype will be found. (+info)Intergenic 16S rRNA gene (rDNA)-23S rDNA sequence length polymorphisms in members of the family Legionellaceae. (5/9)
A method based on PCR amplification of the 16S rRNA gene (rDNA)-23S rDNA intergenic regions was developed for the identification of species within the family Legionellaceae. The sizes of the PCR products varied from 1,353 to 350 bp. Strains of Legionella pneumophila were characterized as having products of approximately 900 and 530 bp, and L. birminghamensis had products of 1,390, 960, and 380 bp. Of the 38 species of legionellae examined, only 7 were indistinguishable (L. erythra from L. rubrilucens, L. anisa or L. cherrii from L. tucsonensis, and L. quateirensis from L. shakespearei). Two environmental isolates were identified as L. pneumophila. Strain LLAP-3, which was a symbiont of amoebae, could not be associated with any Legionella sp. studied. (+info)In situ identification of Legionellaceae using 16S rRNA-targeted oligonucleotide probes and confocal laser scanning microscopy. (6/9)
Bacteria of the family Legionellaceae form a monophyletic group within the gamma-subclass of Proteobacteria. Based on comparative sequence analysis we constructed two oligonucleotide probes complementary to regions of 16S rRNA characteristic for Legionellaceae. Probe specificities were tested by whole-cell or dot-blot hybridization against 14 serogroups of Legionella pneumophila, 22 different Legionella spp. and 72 non-legionellae reference strains. Using optimized conditions both probes hybridized to all tested strains of L. pneumophila. Probes LEG226 and LEG705 hybridized to 71% and 90% of the Legionella species tested, respectively. With the exception of Methylomonas alba none of the non-target strains showed complete sequence homology within the target molecule. In a preliminary evaluation the results of classical techniques employing selective media, immunofluorescence and the probe assay were in good accordance for routine environmental and clinical isolates. L. pneumophila suspended in drinking water at approximately 10(3)-10(4) c.f.u. ml-1 could be rapidly detected by a combination of membrane filtration on polycarbonate filters and whole-cell hybridization. Even after incubation for 1 year a proportion of the released cells was still detectable. In situ hybridization also facilitated visualization of Legionella spp, cells in model biofilms. A combination of in situ hybridization and confocal laser scanning microscopy (CLSM) was used to analyse the three-dimensional arrangement of L. pneumophila within cells of the ciliated protozoan Tetrahymena pyriformis. Whole-cell probing with 16S rRNA-targeted oligonucleotides could, in the future, complement established techniques like immunofluorescence and PCR in ecological and epidemiological studies of Legionellaceae. (+info)Restriction fragment length polymorphism of rRNA genes for molecular typing of members of the family Legionellaceae. (7/9)
Typing of Legionella pneumophila remains important in the investigation of outbreaks of Legionnaires' disease and in the control of organisms contaminating hospital water. We found that the discriminatory power of a nonradioactive ribotyping method could be improved by combining results obtained with four restriction enzymes (HindIII, NciI, ClaI, and PstI). Fifty-eight clinical and environmental L. pneumophila strains including geographically unrelated as well as epidemiologically connected isolates were investigated. Epidemiologically related strains had the same ribotypes independent of the combinations of enzymes used. Some strains belonging to the same serogroup were assigned to different ribotypes, and some ribotypes contained members of different serogroups, indicating, as others have found, that serogroup and genotype are not always related. The discriminatory power of the method was estimated by calculating an index of discrimination (ID) for individual enzymes and combinations thereof. The combined result with all four enzymes was highly discriminatory (ID = 0.97), but results for three enzymes also yielded ID values acceptable for epidemiological purposes. In addition, the testing of 27 type strains and 6 clinical isolates representing Legionella species other than L. pneumophila indicated that ribotyping might be of value for species identification within this genus, as previously suggested. (+info)Legionellaceae in the potable water of Nova Scotia hospitals and Halifax residences. (8/9)
Water was cultured from 39 of 48 hospitals (7 Halifax hospitals and 32 non-Halifax hospitals) in the province of Nova Scotia and from 90 residences (74 private dwellings, 16 apartments) in Halifax to determine the frequency of legionella contamination. Six of seven Halifax hospitals had Legionellaceae isolated from their potable water compared with 3 of 32 non-Halifax hospitals (P < 0.0001). Overall, 19 of 59 (32%) of the water samples from Halifax hospitals were positive for legionellae compared with 5 of 480 (1%) samples from non-Halifax hospitals (P < 0.0000). Five of the six positive Halifax hospitals had Legionella pneumophila serogroup 1 and 1 had L. longbeachae serogroup 2 recovered from their potable water. Legionella contamination was associated with older, larger (> or = 50 beds) hospitals with total system recirculation. These hospitals also had water with a higher pH and calcium content but lower sodium, potassium, nitrate, iron and copper content. Fourteen of the 225 (6.2%) water samples from Halifax residences were positive for legionellae -8% (6/74) of the single family dwellings were positive, compared with 25% (4/16) apartments. The positivity rate of 15.7% for the 19 electric hot-water heaters in Halifax homes was not significantly different from the 32% positivity for Halifax hospitals. L. longbeachae accounted for 2 of the 14 isolates of legionellae from Halifax homes. (+info)Legionellaceae is a family of Gram-negative bacteria that includes the genus Legionella, which are known to cause Legionnaires' disease and Pontiac fever. These bacteria are commonly found in freshwater environments such as lakes and streams, but can also be found in man-made water systems like cooling towers, hot tubs, and decorative fountains. They thrive in warm water (20-45°C) and can survive in a wide range of temperatures and pH levels.
Legionella bacteria become a health concern when they are aerosolized and inhaled, allowing them to infect the lungs and cause respiratory illnesses. Proper maintenance and disinfection of water systems can help prevent the growth and spread of Legionella bacteria.
Legionella is the genus of gram-negative, aerobic bacteria that can cause serious lung infections known as legionellosis. The most common species causing disease in humans is Legionella pneumophila. These bacteria are widely found in natural freshwater environments such as lakes and streams. However, they can also be found in man-made water systems like cooling towers, hot tubs, decorative fountains, and plumbing systems. When people breathe in small droplets of water containing the bacteria, especially in the form of aerosols or mist, they may develop Legionnaires' disease, a severe form of pneumonia, or Pontiac fever, a milder flu-like illness. The risk of infection increases in individuals with weakened immune systems, chronic lung diseases, older age, and smokers. Appropriate disinfection methods and regular maintenance of water systems can help prevent the growth and spread of Legionella bacteria.
Bromthymol Blue is a pH indicator dye that is commonly used in laboratory settings to determine the acidity or alkalinity of a solution. It is a blue, water-soluble compound that turns yellow in acidic solutions with a pH below 6.0 and can turn green, blue, or purple in solutions with a pH between 6.0 and 7.6, depending on the concentration of hydrogen ions present. At a pH above 7.6, Bromthymol Blue turns bright blue-green.
The chemical formula for Bromthymol Blue is C27H35BrClO5S. It has a molecular weight of 609.64 g/mol and a structural formula that includes a thymol blue core with bromine and chlorine atoms attached to it, along with a sulfonate group that makes the compound water-soluble.
Bromthymol Blue is often used in medical and biological research to measure pH changes in bodily fluids such as urine or blood. It can also be used in environmental testing to monitor water quality and detect acid rain, for example. In addition, Bromthymol Blue has been used in educational settings to teach students about pH and chemical indicators.
Legionellosis is a bacterial infection caused by the species Legionella, most commonly Legionella pneumophila. It can manifest in two main clinical syndromes: Legionnaires' disease and Pontiac fever.
Legionnaires' disease is a severe form of pneumonia characterized by cough, high fever, chills, muscle aches, and headaches. Other symptoms may include chest pain, shortness of breath, confusion, and gastrointestinal problems such as diarrhea, nausea, and vomiting. It is often associated with exposure to contaminated water sources like cooling towers, hot tubs, and decorative fountains.
Pontiac fever, on the other hand, is a milder form of legionellosis that causes flu-like symptoms without pneumonia. Symptoms typically include fever, chills, headache, and muscle aches, but they usually resolve within 2 to 5 days without specific treatment.
Both forms of legionellosis are transmitted through inhalation of contaminated aerosols or droplets, and prompt diagnosis and appropriate antibiotic therapy are essential for the management of Legionnaires' disease.
Legionnaires' disease is a severe and often lethal form of pneumonia, a lung infection, caused by the bacterium Legionella pneumophila. It's typically contracted by inhaling microscopic water droplets containing the bacteria, which can be found in various environmental sources like cooling towers, hot tubs, whirlpools, decorative fountains, and large plumbing systems. The disease is not transmitted through person-to-person contact. Symptoms usually appear within 2-10 days after exposure and may include cough, fever, chills, muscle aches, headache, and shortness of breath. Some individuals, particularly those with weakened immune systems, elderly people, and smokers, are at higher risk for developing Legionnaires' disease. Early diagnosis and appropriate antibiotic treatment can improve the chances of recovery. Preventive measures include regular testing and maintenance of potential sources of Legionella bacteria in buildings and other facilities.
Water microbiology is not a formal medical term, but rather a branch of microbiology that deals with the study of microorganisms found in water. It involves the identification, enumeration, and characterization of bacteria, viruses, parasites, and other microscopic organisms present in water sources such as lakes, rivers, oceans, groundwater, drinking water, and wastewater.
In a medical context, water microbiology is relevant to public health because it helps to assess the safety of water supplies for human consumption and recreational activities. It also plays a critical role in understanding and preventing waterborne diseases caused by pathogenic microorganisms that can lead to illnesses such as diarrhea, skin infections, and respiratory problems.
Water microbiologists use various techniques to study water microorganisms, including culturing, microscopy, genetic analysis, and biochemical tests. They also investigate the ecology of these organisms, their interactions with other species, and their response to environmental factors such as temperature, pH, and nutrient availability.
Overall, water microbiology is a vital field that helps ensure the safety of our water resources and protects public health.