Wednesday, January 24, 2024

Streptococci are.. γ-hemolytic. β-hemolytic. α-hemolytic

Streptococci are:

  • A. α-hemolytic.
  • B. β-hemolytic.
  • C. γ-hemolytic.
  • D. ALL.

The answer is D. ALL.

Streptococci are a diverse genus of bacteria, and they can exhibit all three types of hemolytic activity:


These streptococci partially break down red blood cells, creating a greenish discoloration around the colonies on blood agar plates. Examples include Streptococcus pneumoniae and Streptococcus viridans.


These streptococci completely break down red blood cells, resulting in a clear zone of hemolysis around the colonies on blood agar, often described as a "halo effect." Examples include Streptococcus pyogenes (Group A strep) and Streptococcus agalactiae (Group B strep).


These streptococci do not break down red blood cells and don't cause any visible hemolysis on blood agar. Examples include Streptococcus anginosus and Streptococcus bovis.

Therefore, while some streptococci are exclusively α-, β-, or γ-hemolytic, the genus as a whole encompasses all three types.