25. Mode of Action of Antimicrobials Flashcards
(28 cards)
What is the purpose of therapeutic drug monitoring?
Ensures drug is effective but not excessively toxic
Why are antimicrobials that affect the cell wall much more effective in gram + bacteria?
Gram - have an outer membrane and a much thinner cell wall
What is the name of the enzyme that builds peptidoglycan chains?
Transpeptidase
What is the mechanism of action of B lactams?
Target transpeptidase to prevent cross-linking of peptidoglycans
What is the mechanism of action of glycopeptides?
Bind to side chains and prevent cross-linking
What methods of resistance are there to B lactams?
Bacteria can produce enzymes that destroy the B lactam ring
EBSL can destroy B lactam of different antibiotic structures
Cabapenemases can destroy B lactam ring of carbapenems
What is the function of a B-lactamase inhibitor?
Give an example
Mop up B lactamase to ensure the antibiotic still works
Eg. Co-amoxiclav
What is the mechanism of action of quinolones in gram - bacteria?
Inhibits DNA gyrase which inhibits DNA replication
What is the mechanism of action of quinolones in gram + bacteria?
Targets topoisomerase 4 to inhibit DNA replication
What is the mechanism of action of rifampicin?
Binds to RNA polymerase to stop translation
Why does rifampicin have no gram - activity?
Rifampicin is hydrophobic
What is the mechanism of action of anti-metabolites?
Inhibit enzymes which are used to make folic acid
Nucleotides and therefore DNA can’t be produced
Name 2 classes of protein synthesis inhibitors
Aminoglycosidases
Tetracyclines
What is the mechanism of action of gentamicin and doxycycline?
Inhibit binding of tRNA to the 30s ribosome
What is the mechanism of action of chloramphenicol?
Inhibit binding of tRNA to 50s ribosome
What is the mechanism of action of macrolides?
Inhibit RNA-dependent protein synthesis at 50s
What is the mechanism of action of linezolid?
Bind to 50s ribosome
What is the mechanism of action of daptomycin?
Binds to bacterial membranes and causes depolarisation of membrane potential
This inhibits the production of protein, DNA and RNA
What side effect is associated with rifampicin?
oral contraceptive failure
What side effect is associated with clarithromycin?
Increases digoxin levels (used for atrial fib)
Which antibiotics interact with warfarin to increase coagulation?
Ciprofloxacin
Metronidazole
Clarithromycin
Which antibiotic interacts with warfarin to decrease coagulation?
Rifampicin
Which class has nephrotoxic effects with amphotericin B?
Aminoglycosides
What antibiotic interacts with antacids?
Rifampicin
