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Shigella Dysenteriae
''Shigella dysenteriae'' is a species of the rod-shaped bacterial genus ''Shigella''. ''Shigella'' species can cause shigellosis ( bacillary dysentery). Shigellae are Gram-negative, non-spore-forming, facultatively anaerobic, nonmotile bacteria. ''S. dysenteriae'' has the ability to invade and replicate in various species of epithelial cells and enterocytes. Signs and symptoms The most commonly observed signs associated with ''Shigella'' dysentery include colitis, malnutrition, rectal prolapse, tenesmus, reactive arthritis, and central nervous system problems. Further, ''S. dysenteriae'' is associated with the development of hemolytic-uremic syndrome, which includes anemia, thrombocytopenia, and kidney failure. If infected with ''S. dysenteriae'', an individual will experience a severe case of shigellosis. Mortality is higher with ''S. dysenteriae'' type 1. Most cases of shigellosis are in developing countries. Shigellosis outbreaks in Asia, Latin America and Africa have had ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark-field Microscopy
Dark-field microscopy, also called dark-ground microscopy, describes microscopy methods, in both light and electron microscopy, which exclude the unscattered beam from the image. Consequently, the field around the specimen (i.e., where there is no specimen to scatter the beam) is generally dark. In optical microscopes a darkfield condenser lens must be used, which directs a cone of light away from the objective lens. To maximize the scattered light-gathering power of the objective lens, oil immersion is used and the numerical aperture (NA) of the objective lens must be less than 1.0. Objective lenses with a higher NA can be used but only if they have an adjustable diaphragm, which reduces the NA. Often these objective lenses have a NA that is variable from 0.7 to 1.25. Light microscopy applications In optical microscopy, dark-field describes an illumination technique used to enhance the contrast in unstained samples. It works by illuminating the sample with light that wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Nervous System
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilateria, bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and Coelenterata, diploblasts. It is a structure composed of nervous tissue positioned along the Anatomical_terms_of_location#Rostral,_cranial,_and_caudal, rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain, though precursor structures exist in onychophorans, gastropods and lancelets. The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals. Overview In vertebrates, the brain and spinal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antibiotic
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting pathogenic bacteria, bacterial infections, and antibiotic medications are widely used in the therapy, treatment and antibiotic prophylaxis, prevention of such infections. They may either bactericide, kill or bacteriostatic agent, inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity. Antibiotics are not effective against viruses such as the ones which cause the common cold or influenza. Drugs which inhibit growth of viruses are termed antiviral drugs or antivirals. Antibiotics are also not effective against fungi. Drugs which inhibit growth of fungi are called antifungal drugs. Sometimes, the term ''antibiotic''—literally "opposing life", from the Greek language, Greek roots ἀντι ''anti'', "against" and βίος ''bios'', "life"—is broadly used to refer to any substance used against ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serotype
A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or Cell (biology), cells are classified together based on their shared reactivity between their surface antigens and a particular antiserum, allowing the classification of organisms to a Infraspecific name, level below the species. A group of serovars with common antigens is called a serogroup or sometimes ''serocomplex''. Serotyping often plays an essential role in determining species and subspecies. The ''Salmonella'' genus of bacteria, for example, has been determined to have over 2600 serotypes. ''Vibrio cholerae'', the species of bacteria that causes cholera, has over 200 serotypes, based on cell antigens. Only two of them have been observed to produce the potent enterotoxin that results in cholera: O1 and O139. Serotypes were discovered in hemolytic streptococci by the American microbiologist Rebecca Lancefield i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indole
Indole is an organic compound with the formula . Indole is classified as an aromatic heterocycle. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indoles are derivatives of indole where one or more of the hydrogen atoms have been replaced by substituent groups. Indoles are widely distributed in nature, most notably as amino acid tryptophan and neurotransmitter serotonin. General properties and occurrence Indole is a solid at room temperature. It occurs naturally in human feces and has an intense fecal odor. At very low concentrations, however, it has a flowery smell, and is a constituent of many perfumes. It also occurs in coal tar. It has been identified in cannabis. It is the main volatile compound in stinky tofu. When indole is a substituent on a larger molecule, it is called an ''indolyl group'' by systematic nomenclature. Indole undergoes electrophilic substitution, mainly at position 3 (see diagram in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indole Test
The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to convert tryptophan into indole. This division is performed by a chain of a number of different intracellular enzymes, a system generally referred to as "tryptophanase." Biochemistry Indole is generated by reductive deamination from tryptophan via the intermediate molecule indolepyruvic acid. Tryptophanase catalyzes the deamination reaction, during which the amine (-NH2) group of the tryptophan molecule is removed. Final products of the reaction are indole, pyruvic acid, ammonium (NH4+) and energy. Pyridoxal phosphate is required as a coenzyme. Performing a test Like many biochemical tests on bacteria, results of an indole test are indicated by a change in color following a reaction with an added reagent. Pure bacterial culture must be grown in sterile tryptophan or peptone broth for 24–48 hours before performing the test. Following incubation, five drops of K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TSI Slant
250px, TSI agar slant results: (from left) preinoculated (as control), ''P. aeruginosa'', ''E. coli'', '' Shigella_flexneri.html" ;"title="Salmonella Typhimurium'', ''Shigella flexneri">Salmonella Typhimurium'', ''Shigella flexneri'' The Triple Sugar Iron (TSI) test is a microbiological test roughly named for its ability to test a microorganism's ability to ferment sugars and to produce hydrogen sulfide. It is often used to Differential media, differentiate enteric bacteria including ''Salmonella'' and ''Shigella''. Composition The TSI slant is a test tube that contains agar, a pH-sensitive dye ( phenol red), 1% lactose, 1% sucrose, 0.1% glucose, and sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate. All of these ingredients are mixed together, heated to sterility, and allowed to solidify in the test tube at a slanted angle. The slanted shape of this medium provides an array of surfaces that are either exposed to oxygen-containing air in varying degrees ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactose
Lactose is a disaccharide composed of galactose and glucose and has the molecular formula C12H22O11. Lactose makes up around 2–8% of milk (by mass). The name comes from (Genitive case, gen. ), the Latin word for milk, plus the suffix ''-ose'' used to name sugars. The compound is a white, water-soluble, non-Hygroscopy, hygroscopic solid with a mildly sweet taste. It is used in the food industry. Structure and reactions Lactose is a disaccharide composed of galactose and glucose, which form a β-1→4 Glycosidic bond, glycosidic linkage. Its systematic name is β-D-galactopyranosyl-(1→4)-D-glucose. The glucose can be in either the α-pyranose form or the β-pyranose form, whereas the galactose can have only the β-pyranose form: hence α-lactose and β-lactose refer to the anomeric form of the glucopyranose ring alone. Detection reactions for lactose are the Alfred Wöhlk, Wöhlk and William Fearon, Fearon tests. They can be used to detect the different lactose content o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hektoen Enteric Agar
Hektoen enteric agar (HEK, HE or HEA) is a selective and differential agar primarily used to recover '' Salmonella'' and '' Shigella'' from patient specimens. HEA contains indicators of lactose fermentation and hydrogen sulfide production; as well as inhibitors to prevent the growth of Gram-positive bacteria. It is named after the Hektoen Institute in Chicago, where researchers developed the agar. Use The definitive use of HEA is to discriminate between ''Shigella'' and ''Salmonella'', although many other species may grow on these plates. However, while the other bacteria may be clinically relevant, the assay does not discriminate among them. Effectively, HEA uses a metabolic assay to divide colonies into "''Salmonella'' and ''Shigella''" and "everything else". Use of these plates assumes that the user is not interested in other enteric pathogens such as '' Klebsiella'' or '' Escherichia''. The plates contain various sugar sources ( lactose, sucrose, and salicin), none o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DCA Agar
DCA agar ( deoxycholate citrate agar) is a solid bacteriological growth medium used for isolation of enteric pathogens. Uses It is particularly useful for the isolation of organisms that cause bacillary dysentery, salmonella strains that cause food poisoning and ''Salmonella'' Paratyphi. It is not so selective for ''Salmonella'' Typhi. This growth medium is inhibitory to most gut bacteria, in particular species of the genus ''Proteus In Greek mythology, Proteus ( ; ) is an early prophetic sea god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" (''hálios gérôn''). Some who ascribe a specific domain to Prote ...'', although these species do survive on DCA agar. It is therefore essential that suspected pathogens must be subcultured on a less inhibitory medium prior to identification. ''Salmonella spp'' appear to be yellow or colourless colonies, often with a dark centre. As there are many bacteria that also l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
XLD Agar
Xylose lysine deoxycholate agar (XLD agar) is a wikt:selective, selective growth medium used in the isolation of ''Salmonella'' and ''Shigella'' species from clinical samples and from food. The agar was developed by Welton Taylor in 1965. It has a pH of approximately 7.4, leaving it with a bright pink or red appearance due to the indicator phenol red. Sugar Fermentation (biochemistry), fermentation lowers the pH and the phenol red indicator registers this by changing to yellow. Most gut bacteria, including ''Salmonella'', can ferment the sugar xylose to produce acid; ''Shigella'' colonies cannot do this and therefore remain red. After exhausting the xylose supply ''Salmonella'' colonies will decarboxylate lysine, increasing the pH once again to alkaline and mimicking the red ''Shigella'' colonies. Salmonellae metabolise thiosulfate to produce hydrogen sulfide, which leads to the formation of colonies with black centers and allows them to be differentiated from the similarly colour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kidney Failure
Kidney failure, also known as renal failure or end-stage renal disease (ESRD), is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may resolve; and chronic kidney failure, which develops slowly and can often be irreversible. Symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications of acute and chronic failure include uremia, hyperkalemia, and volume overload. Complications of chronic failure also include heart disease, high blood pressure, and anaemia. Causes of acute kidney failure include low blood pressure, blockage of the urinary tract, certain medications, muscle breakdown, and hemolytic uremic syndrome. Causes of chronic kidney failure include diabetes, high blood pressure, nephrotic syndrome, and polycystic kidney diseas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
