Lab 25

Question 1

Agree/Disagree

All antibiotics will be equally effective against gram-positive and gram-negative bacteria

Answer 1

Disagree

Question 2

Agree/Disagree

All antibiotics will be equally effective on the gram-negative E. coli and P. aeruginosa bacteria

Answer 2

Disagree

Question 3

What were the three most effective antimicrobial agents?

Answer 3

tetracydine, cloramphiod, and neomycin

Question 4

Why isn’t one antimicrobial agent equally effective against all three bacteria?

Answer 4

Because each antimicrobial agent inhibits growth differentially by either cell wall structure, permeability, or species

Question 5

Is the disk diffusion technique measuring bacteriostatic or bactericidal activity?

Answer 5

You cannot determine without a subculture

Question 6

In which growth phase is an organism most sensitive to an antimicrobial agent?

Answer 6

log phase

Question 7

Why is the disk diffusion technique not a perfect indication of how the drug will preform in vivo? What other factors are considered before using the antimicrobial agent in vivo>

Answer 7

Variables such as serum, body pH, ionic content, and O2 levels. Other factors to consider are how the drug is metabolized and excreted and the side effect of the drug

Question 8

What are the 4 different methods of action that antimicrobial agents use?

Answer 8

inhibit enzyme activity
inhibit cell wall synthesis
inhibit protein synthesis
inhibit nucleic acid synthesis

Question 9

What effect would the presence of tetracycline in the body have on penicillin therapy?

Answer 9

it will inhibit the effectiveness of penicillin because penicillin is bactericidal and tetracycline is bacteriostatic

Question 10

The larger the zone of inhibition (mm) around an antibiotic the more __________ (effective/ineffective) the antibiotic is

Answer 10

effective

Question 11

Pasteur and other observed that infecting an animal with __________ protected the animal against __________

Answer 11

Pseudomonas aeruginosa, Bacillus anthracis

Question 12

Antibiosis means:

Answer 12

“against life”, Noun

An antagonistic association between two organisms (esp. microorganisms), in which one is adversely affected

Question 13

A substance produced by a microorganism that inhibits other microorganism is called a(n) __________

Answer 13

antibiotic

Question 14

Alexander Fleming found that __________ growth inhibited the growth of many gram-positive cocci and Neisseria spp.

Answer 14

Penicillium mold

Question 15

The antibiotic __________ is effective against may bacteria that penicillin does not affect

Answer 15

steptomycin (in nearly 70% of all antibiotics)

Question 16

Antimicrobial chemicals used internally (whether natural or synthetic) are called __________

Answer 16

antimicrobial drugs

Question 17

Define a pathogen:

Answer 17

a disease causing organism

Question 18

During incubation, the antimicrobial agent diffuses from the disk, from an area of ______ concentration to an area of ______ concentration.

Answer 18

high to low

Question 19

An effective agent will inhibit bacterial growth, and measurements can be made of the size of the ______________________

Answer 19

zones of inhibition

Question 20

How is the minimum inhibitory concentration (MIC) of an antibiotic determined?

Answer 20

By testing for bacterial growth in dilutions of the antibiotic in nutrient broth