For the past week, a 65-year-old woman has been treated for a severe infection with broad-spectrum antibiotics, and she had recovered well. Over the past day, however, she has developed foul-smelling, voluminous, greenish, watery diarrhea, as well as abdominal pain and fever. She is diagnosed with pseudomembranous colitis. Which of the following is the mechanism associated with this condition?

- Pseudomembranous colitiis Overgrowth of C. difficile following antibiotic therapy d/t destruction of normal intestinal flora. Aka Antibiotic-associated colitis / Antibiotic-associated diarrhea Produces exotoxin that induces necrosis of superficial mucosa, -Pseudomembrane formation. Bacteria itself does not invade the mucosa. Histology : small surface erosion of superficial colonic crypts and overlying accumulations of neutrophils, fibrin, mucus, and necrotic epithelial cells Lamina propia adjoining area of necrosis has infiltrate of neutrophils and eosinophils In advanced lesion : necrosis of superficial crypts with more dense neutrophil infiltrate and plaque like pseudomembrane of neutrophil , fibrin, and cellular debris covering mucosal surface