Question

1.

If you were to make Columbia CNA with 5% sheep blood agar plates with twice as much colistin, how would the results likely be affected?

Select one:

a. Less Gram-positive growth, more Gram-negative growth

b. Less Gram-positive growth, no or even less Gram-negative growth

c. More Gram-positive growth, more Gram-negative growth

d. More Gram-positive growth, no or even less Gram-negative growth

e. Same Gram-positive growth, no or even less Gram-negative growth

2.

In Mannitol Salt Agar lab, you were told to invert the plate before incubation. This is a common practice to avoid:

Select one:

a. Condensation drops

b. Increased smell

c. Decrease oxygen content

d. Bacteria from growing in wrong direction

e. Airborne contamination

3.

If you see a yellow halo surrounding a colony on a MSA plate, which of the following is likely to be true?

Select one:

a. Glycolysis occurred

b. The organism is Staphylcoccus epidermidis

c. Colonies are not isolated

d. Fermentation occurred

e. Colony is Gram-negative

4.

Which one of the following is found in MSA plates, but not in NA plates?

Select one:

a. Phenol red

b. Agar

c. Tryptose

d. Peptone

e. Beef extract

5.

Why are the three organisms of Phenylethyl Alcohol Agar lab inoculated on the same plate?

Select one:

a. To avoid contamination

b. For easy viewing purposes.

c. To save resources

d. To avoid fluctuations in medium content and environmental effects.

6.

For which reason would you most likely use a PEA plate for culturing after taking a sample from a patient?

Select one:

a. To isolate Streptococcus and Staphylococcus from other fecal bacteria.

b. To detect Escherichia contamination on the skin.

c. To find E. coli strains associated with food poisoning.

d. To identify gram-negative anaerobes in the patient's flora.