What is the mechanism of action for optochin? Select one: a. Interferes with S.

Question

What is the mechanism of action for optochin?

Select one:

a. Interferes with S. niveus.

b. Interferes with ATPase activity

c. Inhibits cell wall synthesis

d. Inhibits DNA replication

e. Inhibits hemolysis

6.

Why should you stab the agar with your loop after completing the streak?

Select one:

a. To detect beta-hemolysis from oxygen-labile hemolysin

b. To detect Escherichia coli

c. To detect Pseudomonads

d. To make sure it is dead

e. To oxygenate the agar

7.

When hemolysins are present on a blood agar plate, they:

Select one:

a. Change in color

b. Destroy the agar

c. Destroy red blood cells

d. Do not change anything

Explanation / Answer

Optochin is a chemical toxic to some bacteria but harmless to others. This test determines the susceptibility or resistance of the bacterium to optochin. It is useful in the identification of Streptococcus pneumoniae, the alpha-hemolytic Streptococcus which is most commonly susceptible to this chemical. Therefore, it inhibits the DNA replication and forms a clear zone of inhibition under the optochin-impregnated disk placed on a nutrient agar plate seeded with the microbe under investigation.

Hence, the correct answer is option d.

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