Which topical antibacterial agent is known to target gram-negative bacteria?

Gentamicin is an aminoglycoside antibiotic that is often used to target a variety of gram-negative bacteria, given its specific mechanism of action. It works by binding to the bacterial ribosome, inhibiting protein synthesis and leading to bacterial cell death. This ability to effectively combat gram-negative pathogens makes gentamicin a common choice for treating infections caused by these bacteria, especially in cases where resistance to other antibiotics may be a concern.

The other agents listed have different spectrums of activity. Bacitracin primarily targets gram-positive bacteria and is not effective against most gram-negative organisms. Mupirocin is mainly used for gram-positive bacteria, particularly in treating skin infections caused by Staphylococcus aureus, including MRSA. Retapamulin is also more effective against gram-positive bacteria, particularly in treating skin and soft tissue infections.

Therefore, the choice of gentamicin reflects its proven efficacy in targeting gram-negative bacterial infections, making it the correct answer for the question regarding topical antibacterial agents.