Misc β-Lactams

Question 1

Aztreonam

Answer 1

• Monobactam w/stand-alone β-lactam ring
• Active only against G- aerobes
• Resists most β-lactamases of G- organisms

Question 2

Vancomycin

Answer 2

• IV for MRSA or nonresistant Staph if allergic to β-lactams
• Not absorbed orally
• Used for pseudomembranous colitis
• Side effects: otoxicity, nephrotoxicity, Red Man Syndrome (flushing due to histamine release)

Question 3

Bacitracin

Answer 3

• Cidal vs G+ cocci and bailli
• Used topically for minor cuts and scrapes
• Used as an ophthalmic ointment for blepharitis and conjunctivitis
• Side effects: nephrotoxic

Question 4

Fosfomycin

Answer 4

• Used for uncomplicated UTIs in women

Question 5

Mechanism of Aztreonam

Answer 5

• Binds penicillin-binding protein-3 (PBP-3) of G-

* Creates long unstable filamentous bacteria that lyse

Question 6

Mechanism of Vancomycin

Answer 6

• Binds to and prevents removal of D-ala terminus pentapeptide chain attached to N-acetylmuramic acid residues of peptidoglycan

Question 7

Mechanism of Bacitracin

Answer 7

• Complexes with the pyrophosphate preventing dephosphorylation of bactoprenol thus inhibiting cell wall synthesis

Question 8

Mechanism of Fosfomycin

Answer 8

• Complexes with pyrophosphate thus blocking the addition of phosphoenolpyruvate to UDP-N-acetylglucosamine
• Leads to inhibition of cell wall synthesis

Question 9

Televancin

Answer 9

• IV Cidal lipoglycopeptide

* Uses: complicated skin and skin structure infections; hospital acquired and ventilator-assoc. pneumonia from S. aureus

Question 10

What is the mechanism for Televancin?

SE?

Answer 10

• Binds to D-ala terminus
• Disrupts membrane potential → increase membrane permeability
• SE: NVD, taste disturbance and foamy urine
• Potentially teratogenic : caution in pregnancy