Walters - misc. B-lactams and other inhibitors of cell wall synthesis

Question 1

what drug is a monobactam with a stand-alone B-lactam ring and is active only against gram - (resists most B-lactamases of gram - organisms)?

Answer 1

Aztreonam

Question 2

what is the mechanism of Aztreonam?

Answer 2

binds PCN-binding protein 3 of gram - bacteria, creating a long unstable filamentous bacteria that can lyse (excreted unchanged in urine and crosses inflamed meninges)

Question 3

what is Vancomycin used for?

Answer 3

IV for MRSA or nonresistant Staph if allergic to B-lactams (also used orally for pseudomembranous colitis - caused by C.difficile)

Question 4

what is the mechanism for Vancomycin?

Answer 4

binds to and prevents removal of D-ala terminus of pentapeptide chain attached to N-acetylmuramic acid residues of peptidoglycan (inhibits cross-linking and destabilizes membrane)

Question 5

what are 3 side effects of Vancomycin?

Answer 5

ototoxicity, nephrotoxicity and Red man syndrome

Question 6

what is red man syndrome?

Answer 6

caused by a histamine release (vasodilator) after a rapid IV - flushing of upper body and face, hypotension, tachycardia, and shock

Question 7

what is Televancin used for?

Answer 7

complicated skin and skin structure infections; hospital-acquired and ventilator-associated pneumonia from S. aureus (semisynthetic of Vancomycin)

Question 8

what are the 2 mechanisms of Televancin?

Answer 8

binds D-ala terminus and disrupts membrane potential = increasing membrane permeability

Question 9

what are the side effects of Televancin?

Answer 9

NVD, taste disturbances, foamy urine and can be a teratogenic (caution in pregnancy)

Question 10

what is Bacitracin used against?

Answer 10

it is cidal against various gram + cocci and bacilli - Nephrotoxic (used for minor cuts and scrapes or opthalmic - blepharitis/conjunctivitis)

Question 11

what is the mechanism of Bacitracin?

Answer 11

Bacitracin complexes with the pyrophosphate preventing dephosphorylation of bactoprenol - inhibiting cell wall synthesis

Question 12

what is Fosfomycin used for?

Answer 12

for short course treatment of uncomplicated UTIs in women

Question 13

what is the mechanism of Fosfomycin?

Answer 13

complexes with pyrophosphate blocking the addition of phosphoenolpyruvate (PEP) to UDP-N-acetylglucosamine (2nd step in synthesis of the Park Nucleotide) = inhibition of cell wall synthesis *inhibits enolypyruvate transferase