1. A 70-year-old fem ale resident in a nursing facility was adm it ted to the hospital because of fever (101.4°F 38.6°C), diarrhea, and severe abdom inal pain. Four days earlier, the patient had...

1. A 70-year-old fem ale resident in a nursing facility was adm it ted to the hospital because of fever (101.4°F 38.6°C), diarrhea, and severe abdom inal pain. Four days earlier, the patient had started antibiotic treatm ent because of acute tonsillitis due to ß-hem olytic streptococci. Physical exam - ination showed a critically ill patient w ith abdom inal distention and absent bowel sounds. Colonoscopy revealed di use ulcerations and exudative plaques lining the colonic m ucosa. W hich of the follow ing antibiotics m ost likely caused the patient’s disease? A. Gentam icin B. Vancomycin C. Rifam pin D. Aztreonam E. Am picillin