All are true regarding pseudomembranous colitis, except

Clostridium difficile causes acute colitis with bloody diarrhea and pseudomembranous colitis. A common cause of nosocomial diarrhea. The disease follows the use of broad-spectrum antibiotics to which it is resistant. Exotoxin A and B involved in the pathogenesis. It is not a normal commensal, it is an oppounistic organism. Reference: Textbook of Microbiology; Anathanarayan and paniker's; 10th edition; Page no: 270