Antibiotics-A Logical Approach Flashcards
What aspect of a bacteria cells retains the initial dye to appear gram positive?
Thick peptidoglycan cell wall
What 3 ways can bacteria be classified?
Gram status, shape and whether they are aerobic and anaerobic
What are the 3 main types of antibiotics?
Inhibit cell wall synthesis or function, inhibit nucleic acid synthesis or function and inhibit protein synthesis
Name 3 examples of antibiotics that inhibit cell walls?
Penicillin, Cephalosporin and Vancomycin
How do penicillins work?
They are bactericidal
Inhibit cell wall synthesis by preventing peptidoglycan cross linkage thus weakening cell wall
What do the cross links in penicillins consist of?
Proteins in the cell wall that act as transpeptidase enzymes
Why are the cross links in penicillins irreversible?
Acelyation of the active serine site after cleavage of the B-lactam ring
Why is activity pf penicillins lost in the presence of B-lactamase?
It hydrolyses the B-lactam ring
What are the side effects of penicillins?
Rash, nausea, vomiting, diarrhoea, anaphylaxis
Give 2 examples of B-lactamase inhibitors?
Clavulonic acid and tazobactam
How are cephalosporins different to penicillins?
They are less sensitive to B-lactamase
Where can cephalosporins pass through? 2
Placenta and CNS
What is vancomycin effective against?
non-B-lactam bactericidal
Effective against gram positive bacteria including MRSA
How is vancomycin given?
Slowly via IV
Why does vancomycin have to be given slowly?
Prevent red man syndrome
