A 16-year-old girl was admitted to the hospital with a fever and a diffuse pustular rash that had developed earlier that day. Two days before admission, she had sustained a dog bite on her right buttock and was started empirically on a regimen of amoxicillin–clavulinic acid (500 mg 3 times a day) to prevent infection. A tetanus vaccine was also administered. The next day, the patient went to the emergency department because of fever and vomiting. An increased white blood cell count was noted at that time. She was given ticarcillin-clavulanate (3.1 g intravenously) for suspected septic infection and then sent home. The next morning, she had persistent fever and vomiting, as well as a diffuse pustular rash that was first noted on her arms and then spread to her face and, finally, to her legs and back.