What condition is characterized by a bacterial infection of the dermis and subcutaneous fat?

The condition characterized by a bacterial infection of the dermis and subcutaneous fat is cellulitis. This skin infection typically arises when bacteria enter the skin through a break or cut, leading to inflammation, redness, swelling, and pain in the affected area. It primarily affects the deeper layers of the skin, which distinguishes it from other skin conditions that may involve the epidermis or are not primarily infections.

In the context of the other options, empyema refers to the collection of pus in the pleural cavity, often due to pneumonia, which does not pertain to a skin infection. Fasciitis, particularly necrotizing fasciitis, involves infection of the fascia - the connective tissue surrounding muscles, nerves, and blood vessels – but it is more severe and involves a deeper tissue level than cellulitis. Dermatitis, on the other hand, is focused on inflammation of the skin, which can be caused by various factors, including allergies or irritants, but does not specifically denote a bacterial infection.

Thus, cellulitis specifically refers to the bacterial infection in the dermis and subcutaneous fat, making it the accurate choice in this context.