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Group A streptococcal infections are a number of infections with Streptococcus pyogenes, a group A streptococcus (GAS). [1] S. pyogenes is a species of beta-hemolytic Gram-positive bacteria that is responsible for a wide range of infections that are mostly common and fairly mild. If the bacteria enters the bloodstream, the infection can become ...
Streptococcus constellatus: Oropharynx Streptococcus intermedius: Oropharynx Streptococcus mitis: General distribution Streptococcus pyogenes: Upper respiratory tract Streptococcus viridans: Pharynx Acinetobacter spp Anterior urethra Bacteroides spp External genitalia Candida albicans: Anterior urethra, external genitalia Corynebacterium spp
The quellung reaction has been used to identify the 93 known capsular serotypes of Streptococcus pneumoniae in diagnostic settings, but in recent years it has been challenged by the latex agglutination method, and further by molecular typing techniques such as the polymerase chain reaction, which detect DNA and therefore target genetic ...
Hemolyses of Streptococcus spp. (left) α-hemolysis (S. mitis); (middle) β-hemolysis (S. pyogenes); (right) γ-hemolysis (non-hemolytic, S. salivarius) 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.
Chains of S. pyogenes bacteria (orange) at 900× magnification Gram stain of Streptococcus pyogenes. Unlike most bacterial pathogens, S. pyogenes only infects humans. Thus, zoonotic transmission from an animal (or animal products) to a human is rare. [8] S. pyogenes typically colonizes the throat, genital mucosa, rectum, and skin. Of healthy ...
Some bacteria, such as Streptococcus pyogenes, Staphylococcus aureus and Pseudomonas aeruginosa, produce a variety of enzymes which cause damage to host tissues.Enzymes include hyaluronidase, which breaks down the connective tissue component hyaluronic acid; a range of proteases and lipases; DNases, which break down DNA, and hemolysins which break down a variety of host cells, including red ...
Streptolysin O is an oxygen-sensitive cytotoxin, secreted by most group A Streptococcus (GAS), and interacts with cholesterol in the membrane of eukaryotic cells (mainly red and white blood cells, macrophages, and platelets), and usually results in beta-hemolysis under the surface of blood agar. Streptolysin S is an oxygen-stable cytotoxin also ...
Post-streptococcus glomerulonephritis is more often associated with group A strep skin infection than it is with strep pharyngitis, so in a patient with suspected post-strep glomerulonephritis with a negative ASO titer, one can then obtain anti-DNase-B titers which are more sensitive for group A strep and for its various strains.