Question

Of the three drugs often found in over the counter antiseptic creams-polymyxin B, bacitracin, and neomycin- which has a mode of action most similar to that penicillin?

Answer 1

Among the three drugs often found in over-the-counter antiseptic creams—polymyxin B, bacitracin, and neomycin—bacitracin has a mode of action most similar to that of penicillin.

Step-by-step explanation:

Bacitracin and penicillin both interfere with bacterial cell wall synthesis, albeit through different mechanisms. Bacitracin inhibits the dephosphorylation of the lipid carrier molecule, preventing the transport of peptidoglycan precursors across the cell membrane during cell wall synthesis. On the other hand, penicillin inhibits the cross-linking of peptidoglycan chains by targeting enzymes involved in transpeptidation.

While polymyxin B and neomycin have different modes of action—polymyxin B disrupts bacterial cell membranes, and neomycin inhibits protein synthesis—they are not as closely related to penicillin in terms of their mechanism of action. Therefore, among the three options, bacitracin is the one with a mode of action most similar to that of penicillin, as they both target aspects of bacterial cell wall synthesis.