Inhibitors of cell membrane function and cell wall synthesis Flashcards
What colour does gram negative bacteria stain?
Pink
What colour does gram positive bacteria stain?
Purple
What substance decides what colour G -ve/+ve stain?
Peptidoglycan
What are the 3 ways the cell membrane can be disrupted?
Disorganize membrane structure - polymyxins
Alter memebrane permeability - gramicidins
Affect membran enzyme systems - oligomycin
What drug can inhibit cell wall synthesis?
Beta-lactams eg. penicillin
What is the mechanism of action for beta-lactams?
Interferes with peptidoglycan
inhibits transpeptidation enzyme
compete for PBPs which catalyse transpeptidase
How is the antibacterial spectrum of various penicillin determined by?
Ability to cross bacterial peptidoglycan cell wall to reach PBPs
What is natural penicillin active against?
G +ve cocci
Few G -ve cocci
Anerobes
What is Anti-staphylococcal penicillin active against?
S.aureus
What are aminopenicillins active against?
G +ve - e.coli
G -ve - Salmonella
What are extended-spectrum penicillin active against?
Anerobes
G +ve
G -ve
How is penicillin administered?
Oral
I.V.
I.M.
How is penicillin absorbed?
Food lowers absorption
Should be taken on an empty stomach
How is penicillin distributed?
Wide distribution
Does not penetrate CNS unless meninges are inflamed
How is penicillin metabolised?
Usually insignificant
Nafcillin and oxacillin - liver
