Results
Examine medium for growth and hemolytic reactions after 18 - 24 and 48 hours incubation. There are four
types of hemolysis on blood agar media described as:7
1. Alpha hemolysis () is the reduction of hemoglobin to methemoglobin in the medium surrounding the
colony. This produces a green discoloration of the medium.
2. Beta hemolysis () is the lysis of red blood cells, producing a clear zone surrounding the colony.
3. Gamma hemolysis (γ) indicates no hemolysis. No destruction of red blood cells occurs and there is no
change in the medium.
4. Alpha-prime hemolysis (ά) is a small zone of complete hemolysis surrounded by an area of partial lysis.