Lecture 2

Question 1

5 ways that antibiotics inhibit bacteria

Answer 1

1. inhibition of cell wall synthesis (ex: penicillin, bacitracin, cephalosporin, vancomycin)
2. disruption of cell membrane function (ex: polymyxin)
3. inhibition of protein synthesis (tetracycline, erythromycin)
4. inhibition of nucleic acid synthesis (rifamycin, quinolones)
5. action as antimetabolites (sulfonilamide)

Question 2

sulfonilamide prevents the formation of ____, which is necessary for synthesis of amino acids and nucleic acids

Answer 2

folic acid

Question 3

sulfonilamide has similar structure to ____, which is metabolized to folic acid

Answer 3

Para-aminobenzoic acid (PABA)

Question 4

steps in the action of antibiotics

Answer 4

1. drug penetrates the envelope
2. transport into the cell
3. drug binds to target

Question 5

mechanisms of drug resistance

Answer 5

1. synthesis of enzymes that inactivate the drug
2. prevention of access to target site (by inhibiting uptake or increasing secretion of the drug)
3. modification of the target site

Question 6

how antibiotics modify target site

Answer 6

1. modify enzyme activity

2. alteration of metabolic pathway

Question 7

example of synthesis of enzymes to inactivate the drug

Answer 7

beta-lactamases break down beta-lactam ring in pencillins and cephalosporins; transpeptidase does not recognize penicillin and bacteria can still make cell wall

Question 8

example of preventing access to target site

Answer 8

tetracyclines and quinolones

Question 9

example of modifying antibiotic target site

Answer 9

bacteria resistant to sulfa aren’t dependent upon PABA to get their folic acid

Question 10

how does antibiotic resistance spread?

Answer 10

1. chromosome associated resistance
2. plasmid mediated resistance
3. rapid spread of resistance