Friday Warm Up - Antibiotics and the Zone of Inhibition

How many antibiotics does this bacteria seem to be resistant to?

• 2

• 3

• All of them

• None of them

Answer explanation

Resistant bacteria is not killed by the antibiotics. There are 3 antibiotics on the bacteria in the petri dish that seem to be unaffected by the antibiotics. There are two antibiotics that have a large area around them where no bacteria is growing.

Tags

NGSS.HS-LS4-4

Based on the figure, which antibiotic inhibited the growth of the bacteria the most?

• A
• B
• C
• D

Answer explanation

Tags

NGSS.MS-ETS1-3

NGSS.MS-PS1-2

The area where bacteria cannot survive because of the antibiotic:

• zone of inhibition
• zone of prohibition
• the friend zone
• zone of unhappiness

Answer explanation

To inhibit means to stop something.

Inhibition comes from the word "inhibit"

A zone is an area or space

Zone of inhibition is the area or space around the antibiotic where bacteria is not growing.

Tags

NGSS.HS-LS4-5

The highly concentrated antibiotic will spread out more in the dish creating a bigger zone of inhibition

• True

• False

Answer explanation

Concentration can mean how strong something is.

High concentration means the antibiotic is very strong.

Kirby-Bauer antibiotic testing uses antibiotic-containing disks to test bacteria resistance (can't be killed by antibiotic). If the bacteria are susceptible (able to be killed) by the antibiotic, an area of clear space surrounds the disc where bacteria are not able to grow, which is known as the zone of inhibition. A larger zone of inhibition around an antibiotic-containing disk indicates that the bacteria are more sensitive to the antibiotic in the disk or that the antibiotic is stronger.

Poll Question: Which antibiotic on the left has the largest zone of inhibition?

• Gentamicin

• Tetracycline

• Trimethoprim

• Amoxicillin

• Streptomycin

Answer explanation

I kind of thought trimethoprim had the largest zone of inhibition, but it could be a tie with tetracycline?