Question

What type of hemolysis does S. aureus exhibit?

A. Alpha-hemolysis
B. Beta-hemolysis
C. Gamma-hemolysis
D. Delta-hemolysis

Answer 1

S. aureus demonstrates beta-hemolysis, which is the clear lysis of red blood cells observed on blood agar around the bacterial colonies.

Step-by-step explanation:

S. aureus exhibits beta-hemolysis. Beta-hemolysis refers to the complete lysis of red blood cells in the vicinity of bacterial colonies on blood agar plates, resulting in a clear zone surrounding the colonies.

This is different from alpha-hemolysis, which is a partial lysis that creates a greenish color around the colonies, and from gamma-hemolysis, where there is no lysis of red blood cells and therefore no change in the agar surrounding the bacteria.

Group A Streptococci, such as Streptococcus pyogenes, are also known for beta-hemolysis, which is sometimes used in laboratories to identify and differentiate between species.

Answer 2

Staphylococcus aureus exhibits beta-hemolysis, which is a complete lysis of red blood cells around its colonies on Blood Agar Plates, leading to a clear zone indicative of its pathogenicity. Option B. Beta-hemolysis is the correct answer.

Step-by-step explanation:

Type of Hemolysis Exhibited by S. aureus

The bacterium Staphylococcus aureus (S. aureus) exhibits beta-hemolysis when grown on Blood Agar Plates. This type of hemolysis is characterized by the complete lysis of red blood cells around the bacterial colonies, resulting in a clear zone surrounding the colonies. Beta-hemolysis is a distinct reaction that differs from alpha-hemolysis, where the red blood cells are not completely lysed but 'bruised,' and gamma-hemolysis, where no hemolysis is observed.

Streptococcus pyogenes is an example of a Group A Streptococcus which are also beta-hemolytic. In contrast, Group D enterococci exhibit gamma-hemolysis. The ability to produce beta-hemolysis by S. aureus is one of the factors that aids in its identification in a clinical setting.

The hemolytic activity of S. aureus is one aspect of its pathogenic profile, which includes numerous virulence factors such as the enzyme coagulase that induces blood clot formation, among others.