Action Mechanisms of Antimicrobials Flashcards
What are three ways an antimicrobial can act?
Inhibition of cell wall synthesis
Inhibition of protein synthesis
Inhibition of nucleic acid synthesis
What are two classes of antimicrobials that inhibit cell wall synthesis?
Penicillins and cephalosporins (beta-lactams)
Glycopeptides
How do penicillins and cephalosporins work?
Disrupt peptidoglycan synthesis by inhibiting the enzymes (PBS) that cross-link the carbohydrate chains
Allows organism destruction by autolytic enzymes
What is resistant to benzyl-penicillin and why?
Gram negative bacteria as the cell wall is made impermeable by the lipopolysaccharide
Give two examples of glycopeptides
Vancomycin and teicoplanin
How do glycopeptides work?
Inhibit the assembly of a peptidoglycan precursor, therefore work prior to beta-lactams
Glycopeptides are suitable for use on what type of bacteria?
Gram positive, as they cannot penetrate the cell wall of Gram negative bacteria
How are glycopeptides administered?
They are not absorbed from the GI tract, only given parenterally
Describe a contraindication and precaution of vancomycin administration?
Toxicity;
IV should be over a few hours
Pre-dose levels should be monitored
Describe the advantages of using teicoplanin over vancomycin
Less toxic
Single daily dose
Same spectrum
What are four classes of antimicrobial that inhibit protein synthesis?
Aminoglycosides
Macrolides and tetracyclines
Oxazolidinones
Cyclic lipopetide
Name an example of an aminoglycoside
Gentamycin
What type of bacteria are sensitive to aminoglycosides?
Staphylococci and Gram negative bacteria
Streptococci are resistant
Describe the administration of aminoglycosides
Can be injected
Describe a contraindication and precaution of aminoglycoside administration
Renal and hearing toxicity
Careful dosing regime required
