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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.
On blood agar, this appears as wide areas clear of blood cells surrounding bacterial colonies. Gamma-hemolytic species cause no hemolysis. [11] Beta-hemolytic streptococci are further classified by Lancefield grouping, a serotype classification (that is, describing specific carbohydrates present on the bacterial cell wall). [6]
Clinical identification of beta-hemolytic streptococci relies on culturing the bacteria with agar media that has been supplemented with blood. [2] This method allows for beta-hemolysis to be easily identified, which is a critical step in further identification tactics. [2]
The viridans streptococci are a large group of commensal streptococcal Gram-positive bacteria species that are α-hemolytic, producing a green coloration on blood agar plates (hence the name "viridans", from Latin "vĭrĭdis", green), although some species in this group are actually γ-hemolytic, meaning they produce no change on blood agar. [1]
Streptococcal toxic shock syndrome is a rapidly progressing infection causing low blood pressure/shock and damage to organs such as the kidneys, liver and lungs. This type of toxic shock has a ...
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.
Strep throat is caused by the bacteria Streptococcus pyogenes, or group A streptococcus. "These bacteria are contagious and can be spread through droplets when someone coughs or sneezes or through ...
Streptococcus agalactiae (also known as group B streptococcus or GBS) is a gram-positive coccus (round bacterium) with a tendency to form chains (as reflected by the genus name Streptococcus). It is a beta- hemolytic , catalase -negative, and facultative anaerobe .