What condition is Bacitracin and Polymyxin B primarily used to treat?

Bacitracin and Polymyxin B are primarily used in the treatment of bacterial infections of the skin, particularly for conditions like impetigo, which can occur as a result of various irritants, including insect bites. Impetigo is a contagious skin infection characterized by red sores that can rupture, ooze, and form a yellow-brown crust. Bacitracin provides coverage against gram-positive bacteria, while Polymyxin B targets gram-negative bacteria, making their combination particularly effective for managing this type of infection.

The other options do not align with the primary use of these medications. Viral infections are typically treated with antiviral agents, chronic dermatitis often requires corticosteroids or other anti-inflammatory medications, and fungal infections are treated with antifungal agents. Thus, the choice of treating impetigo with Bacitracin and Polymyxin B is correctly focused on their antibacterial properties suitable for that condition.