Which of the following antimicrobial agents makes channels and gram-negative cellular membranes, thus damaging their integrity?

Question

A. Polymyxin

B. Bacitracin

C. Daptomycin

D. Cephalosporin

E. Streptomycin

Which of the following statements regarding resistance to antimicrobial agents is false?

a. Resistance can occur after mutation of a gene coding for the target of an antimicrobial agent so that the drug does not bind effectively to that target.

b. Since very few Beta-Lactamases have been discovered, the mechanism of resistance to Beta-lactams is not well understood

c. Changes to a bacterium's metabolic pathways can result in resistance

d. single bacterium can be resistant to multiple antimicrobial agents

e. Bacteria can achieve resistance by pumping as antimicrobial agent out of the cell before it can act.

Answer 1

Question 1 describes the mechanism of action for polymyxins.

Bacitracin is a topical antibiotic that inhibits bacterial cell wall synthesis. Daptomycin damages the cellular membrane, but only in gram positive organisms. Cephalosporins are beta lactams which inhibit the cell wall synthesis. Streptomycin is an aminoglycoside which work by inhibiting the 30s subunit of the bacterial ribosome.

Question 2 is B. Betalactamases are common and we have discovered ways around them in many cases. Since we have created many work arounds for beta-lactamases, I would consider the resistance to beta-lactams to be well understood.