1-24 Mechanisms of Action of Antibiotics

Question 1

Bacteriostatic

Answer 1

slows the growth of bacteria

Question 2

bacteriocidal

Answer 2

kills bacteria

Question 3

5 modes of action of antibiotics. example of each

Answer 3

1. inhibition of cell wall synthesis - beta lactams
2. inhibition of protein syntehsis - tetracyclines targeting 30s
3. alteration cell membranes - lipopeptides
4. inhibition of nucleic acid synthesis ( fluoriquones block DNA gyrase)
5. antimetabolite activity (sulfas inhibit synthesis pathway)

Question 4

Penicillin

Answer 4

bacteriocidal, irreversibly binds PBP’s preventing further cell wall synthesis

Question 5

cephalosporins

Answer 5

same as penicillins, resist beta lactamase as generations progress.

irreversibly binds PBP’s - preventing further cell wall synthesis

Question 6

glycopeptides

Answer 6

Vancomycin, bacteriocidal

binds to the short amino acid residues hanging off the glycan strands. blocks PBP’s from crosslinking to create cell wall

Question 7

macrolides

Answer 7

bacterioSTATIC

targets the ribosomal subunit (large), preventing protein synthesis

Question 8

Tetracyclines

Answer 8

bacterioSTATIC, targets ribosomal subunit (Small)

Question 9

fluoroquinolones

Answer 9

bacteriocidal agent, interfers with DNA gyrase activity (can no longer supercoil)

inhibits nucleic acid (DNA) synthesis

Question 10

aminoglycosides

Answer 10

bacteriocidal that targets ribosomal subunites, preventing protein synthesis

Question 11

sulfonamides

Answer 11

bacterioSTATIC, inhibits folate syntehsis pathway.

Bactrim - trimethoprim & sulfamethoxazole given together become bacteriocidal. each blocks a portion of the folate pathway.

Question 12

describe how pharmokenetic and pharmodynamic properties may influence whether an antibiotic may or may not be used in treatment of an infection

Answer 12

pharmokinetic - if the antibiotic has toxcitiy at the concentration needed to be effective. Also how often the drug must be given. describes the way the body manupulates the drug

Pharmodynamic - if the antibiotic simply can’t reach the concentration necessary to effect bacteria then the antibiotic will have no effect.
describes the biochemical/physiological effects of teh drug and mechanism of action on bacteria

Question 13

four main beta lactam classes

Answer 13

penicillins, cephalosporins, monobactams, carbapenems

Question 14

fosfomycin

Answer 14

cidal - inhibits muramic acid synthesis (cell wall)

Question 15

linezolid

Answer 15

static - blocks formation of translation initiation complex

Question 16

chloramphenicol

Answer 16

prevents peptide bond formation

Question 17

metronidazole

Answer 17

disrupts DNA synthesis

Question 18

rifampin

Answer 18

inhibits RNA synthesis

Question 19

bactitracin (topical)

Answer 19

inhibits RNA transcription

Question 20

muprocin

Answer 20

blocks tRNA synthesis, eradicates MRSA