(haemolysis)
Breakdown of red blood cells.
The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms, particularly for streptococcal species.
(Types)
• α-hemolysis
• β-hemolysis: CAMP test
• γ-hemolysis
(Comparison)
• hemolysis: Process by which a bacteria use hemolysins (substances that cause hemolysis) to specifically permeabilize and lyse blood cells.
• hemodigestion: Nonspecific killing of blood cells by metabolic by-products of bacteria.
α-hemolysis (green hemolysis, incomplete hemolysis, partial hemolysis): Dark and greenish. Green oxidized derivative methemoglobin caused by hydrogen peroxide produced by the bacteria.
(Example of bacteria)
• Streptococcus pneumoniae
• Streptococcus mutans
• Streptococcus viridans
hemedigestion: It turns green in confluent growth, whereas, no change around single colonies.
(Example of bacteria)
• Vibrio cholerae
β-hemolysis (complete hemolysis): Lightened (yellow) and transparent. Complete lysis of red blood cells in the media caused by streptolysin, an exotoxin, enzyme produced by bacteria.
• Streptolysin O: Oxygen-sensitive cytotoxin, secreted by most Group A streptococcus and Streptococcus dysgalactiae, and interacts with cholesterol in the membrane of eukaryotic cells (mainly red and white blood cells, macrophages, and platelets).
• Streptolysin S: Oxygen-stable cytotoxin also produced by most Group A streptococcus strains. Affects immune cells, including polymorphonuclear leukocytes (neutrophils, eosinophils, basophils, and mast cells) and lymphocytes, and is thought to prevent the host immune system from clearing infection.
CAMP test: Some weakly beta-hemolytic species cause intense β-hemolysis when grown together with a strain of Staphylococcus.
• Streptococcus agalactiae
• Clostridium perfringens
• Listeria monocytogenes
γ-hemolysis (non-hemolytic): Color unchanged. Not induce hemolysis
• Enterococcus faecalis
• Staphylococcus saprophyticus
• Staphylococcus epidermidis
Ещё видео!