Question

17. Which of the following biochemical tests can be used to distinguish potentially pathogenic microorganisms from nonpathogenic microorganisms? Check all that apply (1) ¨ Nutrient agar ¨

Mannitol Salt (MSA) agar ¨

Hydrocarbon ¨

Blood (BA) agar ¨

EMB agar ¨

Nutrient Agar ¨

Tryptic Soy Agar

Answer 1

In given media organism can grow but in blood blood agar is source where pathogenic organism can grow. It is having following reasons:

1. Blood contain preformed antidbodies sometime these antidbodies prevent the growth of microorganism only pathogenic oraganism can grow on this.
2. Blood agar use to check the virulence factor of the micro organism.
3. Some pathogenic organism activate the matrix metalloproteases or plasminogen that helps in the invasion. These microorganism grow on blood agar and give the zone of hemolysis.
4. Different type of hemolysis such as alpha, beta and gamma used for the prelimnary identification of the streptococcus species.

Hence blood agar can detect the potential micro organisms.