|
Weil–Felix Test
The Weil–Felix test is an agglutination test for the diagnosis of rickettsial infections. It was first described in 1916. By virtue of its long history and of its simplicity, it has been one of the most widely employed tests for rickettsia on a global scale, despite being superseded in many settings by more sensitive and specific diagnostic tests. The Weil-Felix antibody was recently found to target rickettsia LPS O-antigen. History and basis for test The basis of the test is the presence of antigenic cross-reactivity between ''Rickettsia'' spp. and certain serotypes of non-motile ''Proteus'' spp., a phenomenon first published by Edmund Weil and Arthur Felix in 1916. Weil-Felix is a nonspecific agglutination test which detects anti-rickettsial antibodies in patient’s serum. Weil-Felix test is based on cross-reactions which occur between antibodies produced in acute rickettsial infections with antigens of OX (OX 19, OX 2, and OXK) strains of Proteus species. Dilution of pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia
''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "rickettsia" has nothing to do with rickets (which is a deficiency disease resulting from lack of vitamin D); the bacterial genus ''Rickettsia'' instead was named after Howard Taylor Ricketts, in honor of his pioneering work on tick-borne spotted fever. Properly, ''Rickettsia'' is the name of a single genus, but the informal term "rickettsia", plural "rickettsias", usually not capitalised, commonly applies to any members of the order Rickettsiales. Being obligate intracellular bacteria, rickettsias depend on entry, growth, and replication within the cytoplasm of living eukaryotic host cells (typically endothelial cells). Accordingly, ''Rickettsia'' species cannot grow in artificial nutrient culture; they must be grown either in tissue or embryo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orientia Tsutsugamushi
''Orientia tsutsugamushi'' (from Japanese ''tsutsuga'' meaning "illness", and ''mushi'' meaning "insect") is a mite-borne bacterium belonging to the family Rickettsiaceae and is responsible for a disease called scrub typhus in humans. It is a natural and an obligate intracellular parasite of mites belonging to the family Trombiculidae. With a genome of only 2.0–2.7 Mb, it has the most repeated DNA sequences among bacterial genomes sequenced so far. The disease, scrub typhus, occurs when infected mite larvae accidentally bite humans. Primarily indicated by undifferentiated febrile illnesses, the infection can be complicated and often fatal. ''Orientia tsutsugamushi'' infection was first reported in Japan by Hakuju Hashimoto in 1810, and to the Western world by Theobald Adrian Palm in 1878. Naosuke Hayashi first described it in 1920, giving the name ''Theileria tsutsugamushi''. Owing to its unique properties, it was renamed ''Orientia tsutsugamushi'' in 1995. Unlike other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunofluorescence
Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specific biomolecule targets within a cell, and therefore allows visualization of the distribution of the target molecule through the sample. The specific region an antibody recognizes on an antigen is called an epitope. There have been efforts in epitope mapping since many antibodies can bind the same epitope and levels of binding between antibodies that recognize the same epitope can vary. Additionally, the binding of the fluorophore to the antibody itself cannot interfere with the immunological specificity of the antibody or the binding capacity of its antigen. Immunofluorescence is a widely used example of immunostaining (using antibodies to stain proteins) and is a specific example of immunohistochemistry (the use of the antibody-antigen rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia Japonica
''Rickettsia japonica'' is a species of ''Rickettsia ''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "ricke ...''. It can cause Japanese spotted fever. References {{Taxonbar, from=Q7331934 Rickettsiaceae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia Africae
''Rickettsia africae'' is a species of ''Rickettsia ''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "ricke ...''. It can cause African tick-bite fever. References Rickettsiaceae {{Alphaproteobacteria-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia Rickettsii
''Rickettsia rickettsii'' (abbreviated as ''R. rickettsii'') is a gram-negative, intracellular, coccobacillus bacterium that is around 0.8 to 2.0 μm long. ''R. rickettsii'' is the causative agent of Rocky Mountain spotted fever. ''R. rickettsii'' is one of the most pathogenic ''Rickettsia'' strains. It affects a large majority of the Western Hemisphere and small portions of the Eastern Hemisphere. History Rocky Mountain spotted fever (RMSF) first emerged in the Idaho Valley in 1896. At that time, not much information was known about the disease; it was originally called Black Measles because patients had a characteristic spotted rash appearance throughout their body. The first clinical description of Rocky Mountain Spotted Fever was reported in 1899 by Edward E. Maxey. Howard Ricketts (1871–1910), an associate professor of pathology at the University of Chicago in 1902, was the first to identify and study ''R. rickettsii''. At this time, the trademark rash now began to slowl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spotted Fever
A spotted fever is a type of tick-borne disease which presents on the skin. They are all caused by bacteria of the genus ''Rickettsia''. Typhus is a group of similar diseases also caused by ''Rickettsia'' bacteria, but spotted fevers and typhus are different clinical entities. Transmission process: When the tick latches on, it needs to be removed under 2 hours. If not noticed or unremoved it takes only 10 hours for the tick to transmit the (disease) to the human. The phrase apparently originated in Spain in the 17th century and was ‘loosely applied in England to typhus or any fever involving petechial eruptions.’ During the 17th and 18th centuries, it was thought to be "cousin-germane" to and herald of the bubonic plague, a disease which periodically afflicted the city of London and its environs during the 16th and 17th centuries, most notably during the Great Plague of 1665.Daniel Defoe, ''A Journal of the Plague Year'', ed. Louis Landa (Oxford, 2010) 219. Types of spotted fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteus Mirabilis
''Proteus mirabilis'' is a Gram-negative, facultatively anaerobic, rod-shaped bacterium. It shows swarming motility and urease activity. ''P. mirabilis'' causes 90% of all ''Proteus'' infections in humans. It is widely distributed in soil and water. ''Proteus mirabilis'' can migrate across the surface of solid media or devices using a type of cooperative group motility called swarming. ''Proteus mirabilis'' is most frequently associated with infections of the urinary tract, especially in complicated or catheter-associated urinary tract infections. Diagnosis An alkaline urine sample is a possible sign of ''P. mirabilis''. It can be diagnosed in the lab due to characteristic swarming motility, and inability to metabolize lactose (on a MacConkey agar plate, for example). Also ''P. mirabilis'' produces a very distinct fishy odor. Disease This rod-shaped bacterium has the ability to produce high levels of urease, which hydrolyzes urea to ammonia (NH3), so makes the urine more a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia Typhi
''Rickettsia typhi'' is a small, aerobic, obligate intracellular, rod shaped gram negative bacterium. It belongs to the typhus group of the ''Rickettsia'' genus, along with ''R. prowazekii''. ''R. typhi'' has an uncertain history, as it may have long gone shadowed by epidemic typhus (''R. prowazekii''). This bacterium is recognized as a biocontainment level 2/3 organism. ''R. typhi'' is a flea-borne disease that is best known to be the causative agent for the disease murine typhus, which is an endemic typhus in humans that is distributed worldwide. As with all rickettsial organisms, ''R. typhi'' is a zoonotic agent that causes the disease ''murine typhus'', displaying non-specific mild symptoms of fevers, headaches, pains and rashes. There are two cycles of ''R. typhi'' transmission from animal reservoirs containing ''R. typhi'' to humans: a classic rat-flea-rat cycle that is most well studied and common, and a secondary periodomestic cycle that could involve cats, dogs, opossums, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensitivity And Specificity
''Sensitivity'' and ''specificity'' mathematically describe the accuracy of a test which reports the presence or absence of a condition. Individuals for which the condition is satisfied are considered "positive" and those for which it is not are considered "negative". *Sensitivity (true positive rate) refers to the probability of a positive test, conditioned on truly being positive. *Specificity (true negative rate) refers to the probability of a negative test, conditioned on truly being negative. If the true condition can not be known, a " gold standard test" is assumed to be correct. In a diagnostic test, sensitivity is a measure of how well a test can identify true positives and specificity is a measure of how well a test can identify true negatives. For all testing, both diagnostic and screening, there is usually a trade-off between sensitivity and specificity, such that higher sensitivities will mean lower specificities and vice versa. If the goal is to return the ratio at w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rickettsia Prowazekii
''Rickettsia prowazekii'' is a species of gram-negative, alphaproteobacteria, obligate intracellular parasitic, aerobic bacillus bacteria that is the etiologic agent of epidemic typhus, transmitted in the feces of lice. In North America, the main reservoir for ''R. prowazekii'' is the flying squirrel. ''R. prowazekii'' is often surrounded by a protein microcapsular layer and slime layer; the natural life cycle of the bacterium generally involves a vertebrate and an invertebrate host, usually an arthropod, typically the human body louse. A form of ''R. prowazekii'' that exists in the feces of arthropods remains stably infective for months. ''R. prowazekii'' also appears to be the closest free-living relative of mitochondria, based on genome sequencing. History Discovery Henrique da Rocha Lima, a Brazilian doctor, discovered this bacterium in 1916. He named it after his colleague Stanislaus von Prowazek, who had died from typhus in 1915. Both Prowazek and Rocha Lima had b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthur Felix
Arthur Felix, FRS (3 April 1887 in Andrychów – 17 January 1956 in England) was a Polish-born microbiologist and serologist. Education and early life Arthur Felix was the son of Theodor Felix, who had an interest in printed textiles and who encouraged his son to study textile dye chemistry. Felix studied chemistry in Vienna and was awarded a Doctor of Science degree. After working in his father's textile printing factory, he returned to Vienna to study microbiology. Arthus Felix was Jewish; he became interested in Zionism during his student days in Vienna and later developed into an authority on Palestine. Career In 1915, Arthur Felix and Edmund Weil were Austrian medical officers working in a field laboratory in Sokal and discovered a bacillus in the urine of patients with typhus. They developed the Weil–Felix test for diagnosis of typhus and other rickettsial diseases. The use of the O and H symbols in the Kauffman–White classification originates from the research by E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
