Lecture 1 - Mechanisms of antibiotics

Question 1

Name the four antibiotic modes of action

Answer 1

Inhibiting cell wall synthesis
inhibiting protein synthesis
interfering with DNA synthesis
disrupting cell membrane

Question 2

Name the 5 antibiotic groups that inhibit cell wall synthesis

Answer 2

Beta lactase - penicillins, cephalosporins, carbapenems

Glycopeptides - vancomycin, teicoplanin

Question 3

How do beta lactams work?

Answer 3

block the active site of penicillin binding protein therefore preventing cross linking within the cell wall

Question 4

Why do you combine beta lactams with clavulanic acid?

Answer 4

most bacteria secrete beta lactamase enzyme which hydrolyses the beta lactase ring within beta lactamase antibiotics. Clavulanic acid has a beta lactam ring which binds to the lactamase enzyme.

Question 5

name one common beta lactam antibiotic combination

Answer 5

co-amoxiclav is amoxicillin and clauvanic acid

Question 6

Name the 5 antibiotic groups that inhibit protein synthesis

Answer 6

aminoglycosides 
tetracyclines 
rifamycins
macrocodes
linosamides

Question 7

give two properties of aminoglycosides and two examples

Answer 7

narrow therapeutic window and nephrotoxic

gentamicin and tobramycin

Question 8

give two properties of tetracyclines and two examples

Answer 8

bacteriostatic - can’t be used in pregnancy or children

doxycycline and tiyecycline (broad spec)

Question 9

when is tobramycin commonly used

Answer 9

to treat pseudomonas in cystic fibrosis

Question 10

name a macrolide and when is it used

Answer 10

clarithromycin and community acquired pneumonia

Question 11

name a rifamycin + when is it used

Answer 11

rifampicin and TB

Question 12

Name a lincosamide

Answer 12

clindamycin

Question 13

how do glycopeptides work

Answer 13

prevent cross linking of cell wall by blocking the binding site of penicillin binding protein

Question 14

What are glycopeptides active against?

Answer 14

broad spec gram positive

Question 15

Name two antibiotic groups that inhibit DNA synthesis and how they work

Answer 15

sulphonamides and diaminopyramidines

inhibit folate synthesis

Question 16

name a diaminopyrimidine and give an example of when it should and shouldn’t be used

Answer 16

trimethoprim shouldn’t be used in the first trimester of pregnancy and should be used with UTIs

Question 17

1) Name an antibiotic group which works by inhibiting DNA replication
2) mechanism

Answer 17

1) quinolone - ciprofloaxin

2) stops the DNA unwinding

Question 18

are fungal cells prokaryotes or eukaryotes ?

Answer 18

eukaryotes

Question 19

organise these mycosis (fungal infections) from most superficial to deep:

candidiasis, aspergillios, tinea, murcomycosis

Answer 19

tinea > candidiasis > myrcomycosis > aspergillios

Question 20

name the three main anti fungal groups and briefly describe how each of them work

Answer 20

polyenes - bind to ergosterol in cell membrane
azoles - inhibit ergosterol synthesis
echinocandins - inhibit gluten synthesis needed for cell wall

Question 21

categorise these beta lactams and one property of each:
ertapenem
fluoxacilin
ceftazidime
ceftazidime
meropenem

Answer 21

categorise these beta lactams and one property of each:
PENICILLINS =
fluoxacilin - better against staph
CEPHALOSPORINS=
ceftazidime - good against pseudo 
cefalexin -
CARBAPENEMS =
ertapenem - oral
meropenem - broad spec