On a blood agar plate, an area of complete hemolysis is classified as which hemolysis type?

On a blood agar plate, an area of complete hemolysis is classified as which hemolysis type?

• A. Beta
• B. Alpha
• C. Gamma
• D. Delta

Answer: (A)

On blood agar, the pattern of red blood cell lysis around colonies helps distinguish organisms by how they affect the surrounding cells. When the zone around the colony is completely clear, with no intact red cells, that is beta hemolysis. The clearing happens because the organism releases hemolysins that lyse red blood cells in the area. By contrast, alpha hemolysis produces only a partial, greenish discoloration from partial hemolysis, and gamma hemolysis shows no change in the agar because there is no lysis. Delta is not a standard category in this context.

On blood agar, the pattern of red blood cell lysis around colonies helps distinguish organisms by how they affect the surrounding cells. When the zone around the colony is completely clear, with no intact red cells, that is beta hemolysis. The clearing happens because the organism releases hemolysins that lyse red blood cells in the area. By contrast, alpha hemolysis produces only a partial, greenish discoloration from partial hemolysis, and gamma hemolysis shows no change in the agar because there is no lysis. Delta is not a standard category in this context.