## **Core Concept**
Topically used sulfonamides are primarily employed in the treatment of ocular infections and as antibacterial agents in dermatological preparations. These agents leverage the antimicrobial properties of sulfonamides to combat bacterial infections.

## **Why the Correct Answer is Right**
Sulfacetamide is a sulfonamide antibiotic used in eye drops and ointments for the treatment of bacterial conjunctivitis. Other sulfonamides like sulfadiazine and silver sulfadiazine are used topically for their antimicrobial properties. However, **Mafenide** is primarily used for its systemic effect in treating severe burns to prevent infection, although it can have topical application; its use is more noted for systemic absorption to reach burn wounds.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Sulfacetamide is indeed used topically, especially in ophthalmology for conjunctivitis.
- **Option B:** Sulfadiazine, when combined with silver as silver sulfadiazine, is used topically for burn creams.
- **Option D:** Sulfamethoxazole is often used systemically in combination with trimethoprim but is less commonly referenced for topical use compared to others.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while sulfonamides have a broad range of applications, their use can be limited by potential allergic reactions and resistance. Topical sulfonamides are particularly useful for localized infections, reducing systemic side effects.

## **Correct Answer:** . Mafenide.