A bacterial specimen exhibits the following growth on blood ag...

Question

A bacterial specimen exhibits the following growth on blood agar. What can you most reasonably conclude about the bacterium? Select all that apply. (NCLEX/HESI/TEAS)

a. It is not S. pyogenes.

b. It is alpha hemolytic.

c. It is beta hemolytic.

d. It is gamma hemolytic.

e. It is Gram-positive.

Accepted Answer

Hello everyone. And welcome back. Our next question says, how does beta hemolysis help differentiate pathogenic bacteria like as pyogenes A by causing discoloration of the er B by producing a greenish pigment around colonies. C by generating a yellow zone around colonies or d by forming a thick opaque layer of growth. So we're talking specifically about bacteria that carry out beta hemolysis. So that would be complete destruction of red blood cells. The example being given is S pyogenes or streptococcus pyogenes, which is a bacteria that causes strep throat among other diseases. So if we have a beta hemolysis, imagine the bacteria growing on blood ager which has blood cells in it everywhere. There's a bacterial colony, you'll be destroying these red blood cells. And the result will be choice c generating a yellow zone around the colonies due to the lysis of those blood cells surrounding the bacterial colony. Now, the one thing that might make us hesitate a moment is choice B producing a greenish pigment of mam the colonies because this has to do with hemolysis as well. But this is a different type of mossis called alpha hemolysis. And there are streptococcus strains that uh cause this result, but not in the case of pyogenes. And again, this is specifically alpha hemolysis, which is not complete discretion destruction of the red blood cells. But oxidation of the hemoglobin protein in the red blood cells. Excuse me, I ran out of space for hemoglobin there. I had to scoot it back over. So it doesn't show that yellow zone because you haven't been completely destroying red blood cells. But the oxidation of the hemoglobin produces this greenish color there as a result. So greenish pigment is going to show you that you have a bacterial species that performs alpha hemolysis. So it still will be in many cases a pathogenic bacteria. But specifically, we're asked, how does beta hemolysis help differentiate pathogenic bacteria? So that's why that one might be just a tiny bit confusing there, but it's not our answer choice. A discoloration of the er this can be caused by different things. You might just have something wrong with your agar or some sort of contamination. But you do see in specific different types of agar. So specifically um in MS A or Manito salt agar, which can be used to identify bacteria with high or tolerance of high salt environments. It can also test for manito fermenting bacteria and this can be a test to see if particular strains of staph bacteria are pathogenic. But again, our question is focusing on beta hemolysis and beta hemolysis does not cause this discoloration of the ger. So choice A is not our answer. And in choice D by forming a thick opaque layer of growth, this just would indicate something that the bacteria you know, gets plenty of nutrients from and can grow in great amounts. And it isn't a result of B beta hemolysis. So it would not be our answer. So once again, how does beta hemolysis help differentiate pathogenic bacteria? Choice C by generating a yellow zone around the colonies? See you in the next video.

Struggling with Microbiology?

A bacterial specimen exhibits the following growth on blood agar. What can you most reasonably conclude about the bacterium? Select all that apply. (NCLEX/HESI/TEAS)
a. It is not S. pyogenes.
b. It is alpha hemolytic.
c. It is beta hemolytic.
d. It is gamma hemolytic.
e. It is Gram-positive.

Watch next

Differential Media practice set

Struggling with Microbiology?

A bacterial specimen exhibits the following growth on blood agar. What can you most reasonably conclude about the bacterium? Select all that apply. (NCLEX/HESI/TEAS)a. It is not S. pyogenes.b. It is alpha hemolytic.c. It is beta hemolytic.d. It is gamma hemolytic.e. It is Gram-positive.

Watch next

Differential Media practice set

A bacterial specimen exhibits the following growth on blood agar. What can you most reasonably conclude about the bacterium? Select all that apply. (NCLEX/HESI/TEAS)
a. It is not S. pyogenes.
b. It is alpha hemolytic.
c. It is beta hemolytic.
d. It is gamma hemolytic.
e. It is Gram-positive.