Final answer:
Exotoxin A (TcdA) and Exotoxin B (TcdB) produced by Clostridium difficile are key virulence factors in the cause of antibiotic-associated pseudomembranous colitis.
Step-by-step explanation:
The virulence factor significant in the cause of antibiotic-associated pseudomembranous colitis caused by Clostridium difficile is Exotoxin A (TcdA) and Exotoxin B (TcdB). These toxins disrupt normal cellular functions by inactivating small GTP-binding proteins, leading to actin condensation, cell rounding, and eventual cell death. The inflammation and destruction of colonic tissues can progress to pseudomembranous colitis, characterized by the formation of a pseudomembrane over the colon lining and symptoms such as watery diarrhea, dehydration, fever, and abdominal pain. Detection of these toxins in a patient who has been recently exposed to antibiotics can indicate a C. difficile infection and the potential for pseudomembranous colitis.