Blood agar with haemodigestion:Introduction and differences between haemodigestion and haemolysis
Haemodgestion in blood agar
Haemodigestion of blood agar showing clear zone no debris but in haemolysis debris persists. Above picture of blood agar is with Vibrio cholerae after 48 hours of incubation at 37°C showing hemodigestion. After overnight incubation on blood agar, the greenish zone appears around the colonies and later becomes clear due to haemodigestion.
Differences between haemodigestion and haemolysis
Hemolysis is the process by which bacteria use proteins (hemolysins) to specifically permeabilize and lyse red blood cells and where as hemodigestion refers to the nonspecific killing of blood cells by metabolic by-products of bacteria. This can be seen on a blood agar plate, when the blood surrounding the confluent part of your streak turns green, but there is no change around single colonies.
Hemolytic patterns:
Complete (β) hemolysis: e.g. Streptococcus pyogenes, Streptococcus agalactiae, Staphylococcus aureus
incomplete (α) hemolysis: Streptococcus pneumoniae, Streptococcus salivarius, viridans are referred to collectively as viridans streptococci, a name derived from viridis (Latin for “green”), referring to the green pigment formed by the partial, α-hemolysis of blood agar. Encapsulated, virulent strains of S. pneumoniae often forming highly mucoid, glistening colonies (production of capsular polysaccharide) surrounded by a zone of α -hemolysis.
and no hemolysis (γ): Enterococcus faecalis
References
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- https://www.researchgate.ne /post/Difference_between_Hemolysis_and_Hemodigestion