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Group A Streptococcus
Lancefield grouping is a system of classification that classifies catalase-negative Gram-positive cocci based on the carbohydrate composition of bacterial antigens found on their cell walls. The system, created by Rebecca Lancefield, was historically used to organize the various members of the family Streptococcaceae, which includes the genera '' Lactococcus'' and ''Streptococcus'', but now is largely superfluous due to explosive growth in the number of streptococcal species identified since the 1970s. However, it has retained some clinical usefulness even after the taxonomic changes, and as of 2018, Lancefield designations are still often used to communicate medical microbiological test results. The classification assigns a letter code to each serotype. There are 20 described serotypes assigned the letters A to V (excluding E, I and J). Bacteria of the genus ''Enterococcus'', formerly known as group D streptococci, were classified as members of the genus ''Streptococcus'' unt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcal Grouping Kit
''Streptococcus'' is a genus of gram-positive bacteria, gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a single coordinate system, axis, thus when growing they tend to form pairs or chains, which may appear bent or twisted. This differs from Staphylococcus, staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cell (biology), cells. Most streptococci are Oxidase test, oxidase-negative and Catalase#Clinical significance and application, catalase-negative, and many are facultative anaerobic organism, facultative anaerobes (capable of growth both aerobically and anaerobically). The term was coined in 1877 by Viennese surgeon Theodor Billroth, Albert Theodor Billroth (1829–1894), by combining the prefix "strepto-" (from ), together with the suffix "-coccus" (from Modern , from .) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-hemolytic
Hemolysis is the breakdown of red blood cells. The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms. This is particularly useful in classifying streptococcal species. A substance that causes hemolysis is called a hemolysin. Types Alpha-hemolysis When alpha-hemolysis (α-hemolysis) is present, the agar under the colony is light and greenish. ''Streptococcus pneumoniae'' and a group of oral streptococci ( ''Streptococcus'' viridans or viridans streptococci) display alpha-hemolysis. This is sometimes called ''green hemolysis'' because of the color change in the agar. Other synonymous terms are ''incomplete hemolysis'' and ''partial hemolysis''. Alpha-hemolysis is caused by the bacteria's production of hydrogen peroxide, which oxidizes hemoglobin and produces the green oxidized derivative methemoglobin. Beta-hemolysis Beta-hemolysis (β-hemolysis), sometimes called ''complete hemolysis'', is a complete lysis of re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactococcus Lactis
''Lactococcus lactis'' is a gram-positive bacterium used extensively in the production of buttermilk and cheese, but has also become famous as the first genetically modified organism to be used alive for the treatment of human disease. ''L. lactis'' cells are cocci that group in pairs and short chains, and, depending on growth conditions, appear ovoid with a typical length of 0.5 - 1.5 μm. ''L. lactis'' does not produce spores ( nonsporulating) and are not motile ( nonmotile). They have a homofermentative metabolism, meaning they produce lactic acid from sugars. They've also been reported to produce exclusive L-(+)- lactic acid. However, reported D-(−)-lactic acid can be produced when cultured at low pH. The capability to produce lactic acid is one of the reasons why ''L. lactis'' is one of the most important microorganisms in the dairy industry. Based on its history in food fermentation, ''L. lactis'' has generally recognized as safe (GRAS) status, with few case report ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcus Mitis
''Streptococcus mitis'' is a species of Gram-positive, mesophilic, alpha-hemolytic bacteria in the genus ''Streptococcus'', belonging to the viridans streptococci group. These bacteria are facultative anaerobes, and made up of non-motile and non-sporing cocci (round cells) that are catalase negative. It is a commensal and commonly inhabits the human mouth, throat, and upper respiratory tract, as part of the oral microbiota. They are clinically important for humans, as under certain conditions, it can cause opportunistic infections, such as infective endocarditis. Classification Members of the ''Streptococcus'' genera belong to lactic acid bacteria defined by the formation of lactic acid as an end-product of carbohydrate metabolism. The family ''Streptococcaceae'' is characterized by based upon its 16S rRNA gene sequence analysis within the low (< 50 mol%) G+C branch. There are over 50 species in the genus which are classified by their 16S rRNA sequences. < ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcus Salivarius
''Streptococcus salivarius'' is a species of coccus, spherical, gram-positive, facultative anaerobic organism, facultative anaerobic lactic acid bacteria that is both Catalase#Catalase test, catalase and oxidase test, oxidase negative. ''S. salivarius'' colony (biology), colonizes (usually in chains) the oral cavity and upper respiratory tract of humans just a few hours after birth, making further exposure to the bacteria harmless in most circumstances. The bacterium is considered an opportunistic infection, opportunistic pathogen, rarely finding its way into the bloodstream, where it has been implicated in cases of sepsis in people with neutropenia, (a deficiency in white blood cells). ''S. salivarius'' has distinct characteristics when exposed to different environmental nutrients. For example, in the laboratory, if a growth medium is used that includes sucrose then ''S. salivarius'' is able to use the sucrose to produce a capsule around itself. However, if sucrose is replaced b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcus Sanguis
''Streptococcus sanguinis'', formerly known as ''Streptococcus sanguis'', is a Gram-positive facultative anaerobic coccus species of bacteria and a member of the Viridans Streptococcus group. ''S. sanguinis'' is a normal inhabitant of the healthy human mouth where it is particularly found in dental plaque, where it modifies the environment to make it less hospitable for other strains of Streptococcus that cause cavities, such as ''Streptococcus mutans''. Pathogenicity ''S. sanguinis'' may gain entrance to the bloodstream when opportunity presents (dental cleanings and surgeries) and colonize the heart valves, particularly the mitral and aortic valves, where it is the most common cause of subacute bacterial endocarditis. For this reason, oral surgeons often prescribe a short course of antibiotics to be taken a few days before to a few days after oral surgery. Once an infection has occurred, treatment is much more complicated and generally involves the administration of several w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcus Anginosus
''Streptococcus anginosus'' is a species of ''Streptococcus''. This species, '' Streptococcus intermedius'', and '' Streptococcus constellatus'' constitute the ''anginosus'' group, which is sometimes also referred to as the ''milleri'' group after the previously assumed but later refuted idea of a single species ''Streptococcus milleri''. Phylogenetic relatedness of ''S. anginosus, S. constellatus, and S. intermedius'' has been confirmed by rRNA sequence analysis. General characteristics The majority of ''Streptococcus anginosus'' strains produce acetoin from glucose, ferment lactose, trehalose, salicin, and sucrose, and hydrolyze esculin and arginine. Carbon dioxide can stimulate growth or is even required for growth in certain strains. ''Streptococcus anginosus'' may be beta-hemolytic or nonhemolytic. The small colonies often give off a distinct odor of butterscotch or caramel. Among the nonhemolytic strains, certain ones produced the alpha reaction on blood agar. However, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterococcus Durans
''Enterococcus durans'' is a species of ''Enterococcus''. It is a gram-positive, catalase- and oxidase-negative, coccus bacterium. The organism is also a facultative anaerobic organism. Prior to 1984, it was known as ''Streptococcus durans''. Certain strains have also been identified as producers of anti-inflammatory agents, which are being studied in medical research. ''E. durans'' is less commonly isolated in clinical infections than ''E. faecalis'' and '' E. faecium'', but it has been increasingly recognized in hospital settings, particularly in patients with urinary catheters and prolonged antibiotic exposure. Metabolism In terms of metabolism, ''E. durans'' primarily shares its substrate utilization profile with ''E. faecium''. It can metabolize L-arabinose (weakly), melibiose and lactose which aids in its biochemical distinction from ''E. faecalis''. ''E. durans'' is often misidentified in clinical diagnostics due to phenotypic overlap with ''E. faecium'', especially w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterococcus Faecium
''Enterococcus faecium'' is a Gram-positive, gamma-hemolytic or non-hemolytic bacterium in the genus ''Enterococcus''. It can be commensal (innocuous, coexisting organism) in the gastrointestinal tract of humans and animals, but it may also be pathogenic, causing diseases such as neonatal meningitis or endocarditis. Vancomycin-resistant ''E. faecium'' is often referred to as VRE. Pathogenic properties This bacterium has developed multi-drug antibiotic resistance and uses colonization and secreted factors in virulence (enzymes capable of breaking down fibrin, protein and carbohydrates to regulate adherence bacteria to inhibit competitive bacteria). The enterococcal surface protein (Esp) allows the bacteria to aggregate and form biofilms. Additional virulence factors include aggregation substance (AS), cytosolin, and gelantinase. AS allows the microbe to bind to target cells and it facilitates the transfer of genetic material between cells. By producing the enterocins A, B, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterococcus Faecalis
''Enterococcus faecalis'' – formerly classified as part of the group D '' Streptococcus,'' is a Gram-positive, commensal bacterium naturally inhabiting the gastrointestinal tracts of humans. Like other species in the genus '' Enterococcus'', ''E. faecalis'' is found in healthy humans and can be used as a probiotic. The probiotic strains such as Symbioflor1 and EF-2001 are characterized by the lack of specific genes related to drug resistance and pathogenesis. Despite its commensal role, ''E. faecalis'' is an opportunistic pathogen capable of causing severe infections, especially in the nosocomial (hospital) settings. ''Enterococcus'' spp. is among the leading causes of healthcare-associated infections ranging from endocarditis to urinary tract infections (UTIs). Hospital-acquired UTIs are associated with catheterization because catheters provide an ideal surface for biofilm formation, allowing ''E. faecalis'' to adhere, persist, and evade both the immune response and antibiot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcus Zooepidemicus
''Streptococcus zooepidemicus'' is a Lancefield group C streptococcus that was first isolated in 1934 by P. R. Edwards, and named Animal pyogens A. It is a mucosal commensal and opportunistic pathogen that infects several animals and humans, but most commonly isolated from the uterus of mares. It is a subspecies of ''Streptococcus equi'', a contagious upper respiratory tract infection of horses, and shares greater than 98% DNA homology, as well as many of the same virulence factors. Morphology ''Streptococcus zooepidemicus'' are gram-positive, non-sporulating, non-motile, catalase and oxidase negative cocci. S. zooepidemicus is encapsulated, with a capsular polysaccharide containing hyaluronic acid, as well as being facultative anaerobes. The cells usually form in pairs, or as long chains. When plated on agar, colonies are usually 0.5-1.5 mm in diameter, circular, and opaque colored. They also have a smooth surface and a convex elevation. Its optimal temperature of growth is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streptococcus Equi
''Streptococcus'' is a genus of gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs along a single axis, thus when growing they tend to form pairs or chains, which may appear bent or twisted. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes (capable of growth both aerobically and anaerobically). The term was coined in 1877 by Viennese surgeon Albert Theodor Billroth (1829–1894), by combining the prefix "strepto-" (from ), together with the suffix "-coccus" (from Modern , from .) In 1984, many bacteria formerly grouped in the genus ''Streptococcus'' were separated out into the genera ''Enterococcus'' and '' Lactococcus''. Currently, over 50 species are recog ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
