TOPICS: Clostridium difficile, bacteria, gram positive, bacilli, spore-forming, obligate anaerobe, intestinal flora, antibiotic exposure, toxin A, enterotoxin, toxin B, cytotoxin, cytoskeleton, pseudomembranous colitis, diarrhea, stool PCR, oral vancomycin, metronidazole, fidaxomicin, fecal transplant