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(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. This is particularly useful in classifying streptococcal species. A substance that causes hemolysis is called a hemolysin.
Streptococcus pneumoniae and a group of oral streptococci (Streptococcus viridans or viridans streptococci) display alpha-hemolysis. Alpha-hemolysis is also termed incomplete hemolysis or partial hemolysis because the cell membranes of the red blood cells are left intact.
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 ...
However, both Streptococcus dysgalactiae and the Streptococcus anginosus group can possess group A antigen as well. Group A streptococci, when grown on blood agar, typically produce small (2–3 mm) zones of beta-hemolysis, a complete destruction of red blood cells. The name group A (beta-hemolytic) Streptococcus is thus also used. [1]
Group B streptococcal infection, also known as Group B streptococcal disease or just Group B strep infection, is the infectious disease caused by the bacterium Streptococcus agalactiae. Streptococcus agalactiae is the most common human pathogen belonging to group B of the Lancefield classification of streptococci —hence the name of group B ...
This group is referred to as alpha-hemolysis because the cell membrane of red blood cells is left intact. [2] When cultured, alpha-hemolysis can be deemed present when the agar gel appears greenish. [2] Identifying and diagnosing alpha-hemolytic Streptococcus is done with a sputum gram stain and culture test. [5]
Group A strep, aka group A Streptococcus, is a bacteria that can cause a range of infections, according to the CDC. Those include strep throat, impetigo, and cellulitis. Those include strep throat ...
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 .