Antibiotic mode of action

Question 1

What do bacteriosidal and bacteriostatic mean?

Answer 1

bacteriosidal = kills micro-organisms
bacteriostatic = inhibits growth of micro-organisms

Question 2

What are the three types of antimicrobials?

Answer 2

antiseptics -kill pathogens, too toxic for internal use so used on skin
disinfectants -kill pathogens, too toxic for internal use so used on inanimate surfaces

antibiotics -kill or inhibit growth of pathogens, can be ingested/injected into body w/minimal side effects

Question 3

What are the requirements of antibiotics?

Answer 3

-kill or inhibit pathogen
-selectively toxic (exploits differences between pathogen and host)
-pharmokinetics (distribution in body)

desirable:
-few side effects
-kill/inhibit broad spectrum of pathogens

Question 4

What can be targets for antibiotics?

Answer 4

-cell wall biosynthesis
-protein synthesis
-nucleic acid biosynthesis
-cytoplasmic membrane functions

Question 5

What do beta lactams target?

Answer 5

-peptidoglycan cell wall biosynthesis
-inhibit penicillin binding proteins (PBPs) needed for transpeptidation and transglycosylation reactions in peptidoglycan biosynthesis

eg. penicillin, ampicilin, methicillin

Question 6

What does gramicidin target?

Answer 6

cytoplasmic membrane
-forms cation channels so that H+ leak out of cell
-pmf can’t be maintained

Question 7

What does kanamycin target?

Answer 7

protein synthesis
-binds to 30S subunit of ribosome, blocking 50S from binding

Question 8

What does rifamycin target?

Answer 8

RNA synthesis
-inhibits RNAP