Question

what is the significance of hemolysis on blood agar?

Answer 1

The significance of hemolysis on blood agar

Hemolysis is break down of erythrocyte in blood agar

1. This help in Classification of streptococci bacteria based on their hemolytic properties

There are 3 types of hemolytic reactions alpha ,beta and gamma

Alpha hemolytic reaction

In this the streptococci producers a greenish discoloration around the colonies . This is due to partial hemolysis . The zone of lysis is small around 1 to 2 mm wide with presence of unlysed erythrocytes which are detected with the help of microscope

This alpha hemolysis is seen in virdan and pneumococcus group of streptococcus

Beta hemolysis

In this a clear and colourless zone of hemolysis is seen around colonies which is large around 2 to 3 mm wide . In this zone erythrocyte are completely lysed .

This lysis is due to production of streptolysin o and streptolysin S

Streptolysin s is responsible for surface hemolysis

Most of the pathogenic streptococci fall in this group

Streptococcus pyogens are the most important and responsible for human infection

Gamma hemolysis

In this category the bacteria doesn't produce hemolysis there is no hemolysis seems near the colonies of the bacteria

The example of gamma hemolysis is streptococcus faecalis

2. Hemolysis on blood agar is also used in identification of group b streptococci with the help of CAMP reaction

3. Reverse camp reaction is also an example of hemolysis on blood agar

Which is used for identification of clostridium species

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