This is an example of pseudomembranous enterocolitis. The mucosal surface of the colon seen here is hyperemic and is partially covered by a yellow-green exudate. The mucosa itself is not eroded. Broad spectrum antibiotic usage (such as clindamycin) and/or immunosuppression allows overgrowth of bacteria such as I>Clostridioides difficile or Staphylococcus aureus or fungi such as Candida to cause this appearance. The colonoscopic appearance is seen below. The majority of cases are due to C difficile infection (CDI), and diagnosis is aided by a two-step laboratory stool testing strategy with immunoassays highly sensitive for glutamate dehydrogenase and for highly specific for CDI A/B toxins.