A 63-year-old woman is hospitalized because of refractory cellulitis. An intravenous cephalosporin is started, and she appears to be improving. On the fifth hospital day, however, she develops profuse diarrhea and a low-grade fever. Her abdomen is soft, with minimal diffuse tenderness to deep palpation and normal bowel sounds. Which of the following is the most likely diagnosis? a- Cryptosporidium infection b- Clostridium difficile infection c- Enterotoxigenic Escherichia coli toxin ingestion d- drug fever Please can you help me?