Severe rash after dermatitis

An 18-year-old Caucasian woman came to the emergency department with a pruritic rash and localized swelling, most marked in the periorbital area. The rash had started 5 days earlier on her upper lip and subsequently spread to her face and upper chest.

Two days before, the patient was treated with amoxicillin/clavulanate (Augmentin), prednisone, and hydroxyzine (Atarax), but her symptoms worsened. She said she felt feverish but did not have any visual disturbances. She had no contacts with others ill with herpes or Varicella, although she did admit to having an unprotected sexual encounter 2 weeks before the rash’s onset. Her medical history was significant for untreated atopic dermatitis.

On exam, the patient was afebrile and had a diffuse maculopapular rash with areas of confluence over her face and hands (Figure 1). The face and hands also showed crusting and scaling. Discrete lesions were found on her upper and lower back (Figure 2), chest, volar wrist, and popliteal fossa. No vesicular lesions were present, although some isolated scabbed areas suggested previous vesicular lesions. The facial lesions were tender to palpation, and there was periorbital edema. No oral lesions were seen. Wound cultures grew methicillin-resistant Staphylococcus aureus.

FIGURE 1
Rash covering the face

FIGURE 2
Lesions on the upper back

What is the diagnosis?
How can the diagnosis be confirmed?
How should this disease be treated?