antibiotic lecture

Question 1

big names in penecillin

Answer 1

alex fleming, ernst chain and howard flory

Question 2

traits of an ideal antibiotic

Answer 2

broad spectrum of activity
wouldn’t induce resistance
high therapeutic index (want a dose that’s effective against pathogen w/out being too toxic to you; 1=you need a toxic dose to kill path)
selective toxicity

Question 3

targets for antibiotics

Answer 3

inhibit cell wall synth
disrupt cell membrane fcn
inhibit prot synth
inhibit nucleic acid synth
act as antimetabolite

Question 4

places where cell wall synth can be inhibited

Answer 4

linking NAG and NAM
linking NAM and peptide
stoping NAM-NAGs from transporting into periplasmic space
inhibit polymerization
inhibit peptide side chain bonds

Question 5

how does penecillin work?

Answer 5

prevents peptide bond (btwn lys-ala on gram + or DAP or ala on gram -) by not letting the bact cleave off the terminal d-ala (the subterminal d-ala binds) penicillin out competes and is cleaved instead (cleaves into even more toxic form)

Question 6

base structure of penecillin

Answer 6

B-lactin ring

Question 7

how does polymyxin work?

Answer 7

displaces LPS molecule in gram - bact causing instability

Question 8

how does inhibition of prot synth work?

Answer 8

can target in many places such as:
formation of ribosome subunits
inhib. of tRNAs from bringing in AA’s
can change configuration of ribosome (changes tunnel or binding groove)
inhibits start site recognition (trunkated cycle)
prevents peptide elongation

Question 9

prob w/ drugs that inhibit nuc. acid synth and what’s the exception?

Answer 9

too toxic

metronidazole

Question 10

how does metronidazole work?

Answer 10

inert in aerobic environment but activated by anaerobic microbes

Question 11

how do sulfanilamides work?

Answer 11

work as antimetabolites and sub in for things bact need with similar structure
ex. stop PAB from turning into folic acid b/c looks v. similar

Question 12

steps of action of antibiotics

Answer 12

penetration into the envelope
transport into the cell
bind target

Question 13

ways antibiotic resistance spreads

Answer 13

chromosome associated resistance,
plasmid mediated resistance
rapid spread of natural resistance thru selective pressures

Question 14

how do drugs affect ea other?

Answer 14

synergism (kill everything well together)
antagonism (stop ea. other from working)
indifference (target diff things)

Question 15

probs w/ giving lots of antibiotics

Answer 15

makes super resistant if doesn’t kill everything, or causes synergistic toxicity in host