Antibiotics Flashcards
What is the route of bacterial DNA synthesis?
PABA - DHOp synthase
DHOp
DHF - DHF reductase
THF
What is the mechanism of bacterial genomic replication?
DNA gyrase
RNA polymerase
How do bacteria synthesise proteins?
Use ribosomes, smaller subunits e.g. 30s,50s
What drugs inhibit DNA synthesis?
Sulphonamides inhibit DHOp synthase
Trimethoprim inhibits DHF reductase
What drugs inhibit genomic replication?
Fluoroquinolones inhibit DNA gyrase
Rifamycins inhibit RNA polymerase
How is peptidoglycan formed?
NAM + NAG associate on pentapeptide forming peptidoglycan
PtG transported across membrane by bactoprenol
PtG incorporated into cell wall when transpeptidase enzyme cross links PtG pentapeptides
What drugs inhibit PtG synthesis?
Glycopeptides (Vancomycin) bind to pentapeptide preventing NAM and NAG association
What drugs inhibit PtG incorporation?
beta lactams bind to transpeptidase inhibiting PtG incorporation
eg. Carbapanems
cephalosporins
penicillins
What drugs inhibit cell wall stability?
lipopeptide - disrupt gram +ve walls
polymyxins - disrupt gram -ve membranes
What are some resistance mechanisms that can be modelled as a pacman?
Additional target: bacteria produce another target that is unaffected by drug e.g. different DHF reductase enzyme produced, resistant to trimethoprim
Alterations in target enzymes: enzyme still effective but drug ineffective
What are some resistance mechanisms that can be modelled as asteroids?
Hyperproduction: bacteria significantly increase levels of DHF reductase. Trimethoprim less effective
What are some resistance mechanisms that can be modelled as frogger?
Alterations in drug permeation: reductions in aquaporins and increased efflux systems
important in gram -ve bacteria
What are some resistance mechanisms that can be modelled as space invaders?
Production of destruction enzymes: beta lactamases hydrolyse CN bond of beta lactam ring
e.g penicillin resistance
flucloxacillin is beta lactamase resistant
