Week 10: Using Growth Patterns for Diagnosis and Treatment (Part 2)

Question 1

where is the highest concentration of antibiotic on a kirby bauer assay?

Answer 1

closest to the disc

Question 2

what is the name of what develops around the antibiotic discs on a kirby bauer?

Answer 2

zone of inhibition

Question 3

what influences the size of the zone of inhibition? (2)

Answer 3

susceptibility of organism tested, as well as other factors

Question 4

how does kirby bauer work?

Answer 4

deposit disc, watch the zone of inhibition grow

Question 5

what is kirby bauer testing for?

Answer 5

susceptibility of a bacteria to an antibiotic

Question 6

why is it important to know what a bacterium is susceptible to?

Question 7

name three antibiotics that we used in the lab

Answer 7

• kanamycin/tetracycline
• penicillin
• novobiocin

Question 8

what does kanamycin/tetracycline target? what does that cause?

Answer 8

targets the 30S ribosomal subunit, causing misreading of t-RNA

Question 9

name the broad spectrum antibiotics

Answer 9

kanamycin/tetracycline

Question 10

name the narrow spectrum antibiotics

Answer 10

penicillin, novobiocin

Question 11

broad or narrow spectrum: kanamycin

Answer 11

broad

Question 12

broad or narrow spectrum: tetracycline

Answer 12

broad

Question 13

broad or narrow spectrum: penicillin

Answer 13

narrow

Question 14

broad or narrow spectrum: novobiocin

Answer 14

narrow

Question 15

what does penicillin target?

Answer 15

transpeptidase

Question 16

what is transpeptidase? why are we talking about it rn?

Answer 16

the enzyme that forms the crosslinking in the peptidoglycan layer of the membrane. targeted by penicillin.

Question 17

what does novobiocin target?

Answer 17

DNA gyrase of Staphylococcus species

Question 18

what process does penicillin target?

Answer 18

peptidoglycan synthesis of bacteria

Question 19

DNA gyrase of Staph. species is targeted by?

Answer 19

novobiocin

Question 20

30S ribosomal subunit is targeted by…

Answer 20

kanamycin or tetracycline

Question 21

transpeptidase is targeted by

Answer 21

penicillin

Question 22

what is penicillin effective against, ineffective against? why?

Answer 22

G+: effective

G-: ineffective

has to do with the thickness of the cell wall

Question 23

pros of broad spectrum drugs

Answer 23

effective against a wide variety of bacteria, useful when the exact pathogen is not known

Question 24

cons of broad spectrum drugs

Answer 24

the use of broad spectrum antibiotics play a key role in the spread of antibiotic resistance

Question 25

pros of narrow spectrum drugs

Answer 25

effective only against a subset of bacteria, depending on its mode of action. helps stop the spread of antibiotic resistance

Question 26

cons of narrow spectrum drugs

Answer 26

need to know more about the identity of the bacteria first, effective only against a subset of bacteria

Question 27

what is an example of how antibiotic resistance is on the rise?

Answer 27

MRSA

Question 28

what does MRSA stand for?

Answer 28

methicillin resistant Staphylococcus aureus

Question 29

what is MRSA?

Answer 29

a common pathogen of skin and wounds that spreads through contact with infected/carrier individuals

Question 30

how to treat MRSA infection?

Answer 30

drugs with a low therapeutic index

Question 31

how to prevent spread of MRSA infection?

Answer 31

proper hygienic practices

Question 32

why is drug resistance growing?

Answer 32

misuse/irresponsible use of antibiotics