Streptococcus pneumoniae is an alpha-hemolytic bacterial species. If Streptococcus pneumoniae is grown on a blood agar plate, what characteristics will the zone of clearance for this species have?

• A. The zone of clearance will be large and bright yellow in color.
• B. The zone of clearance will be small and a greenish color.
• C. This bacterial species will show no zone of clearance on a blood agar plate.

Answer: (B)

Verified step by step guidance

1. Understand the concept of hemolysis: Hemolysis refers to the breakdown of red blood cells, and different bacteria exhibit different types of hemolysis on blood agar plates.
2. Identify the type of hemolysis: Streptococcus pneumoniae is known to be alpha-hemolytic. Alpha-hemolysis is characterized by partial hemolysis of red blood cells.
3. Recognize the appearance of alpha-hemolysis: On a blood agar plate, alpha-hemolysis results in a greenish discoloration around the bacterial colonies due to the partial breakdown of hemoglobin.
4. Compare with other types of hemolysis: Beta-hemolysis results in a clear, colorless zone due to complete lysis of red blood cells, while gamma-hemolysis shows no change in the blood agar.
5. Conclude the characteristics of the zone of clearance: For Streptococcus pneumoniae, the zone of clearance will be small and greenish in color, indicating partial hemolysis typical of alpha-hemolytic bacteria.