Clinical Significance
Many early studies have suggested that toxin A (also known as TcdA) is the major toxin protein causing antibiotic-associated diarrhea (AAD); however, research scientists within last decade or so have shown that Toxin B (or TcdB) plays a more important role in disease than anyone had forecasted. With this knowledge, Toxin B has been identified as the major virulence factor that causes the opening of tight junctions of intestinal epithelial cells, which enables toxin to increase vascular permeability and induce hemorrhaging. Hence, this leads to tumor necrosis factor α (TNF α) and proinflammatory interleukins being established as the major causative agents of pseudomembranous colitis (PMC) and antibiotic-associated diarrhea (AAD).
The involvement of toxin A and—most importantly—toxin B is the key element that determines the disease caused by C. difficile. Clinical laboratories have identified these toxins in patients' stool based on antibody and cytotoxicity assays. These bacterial toxins have been shown to be associated with Clostridium sordellii hemorrhagic toxin (TcsH), lethal toxin (TcsL), and Clostridium novyi alpha toxin (Tcn α), thus, making this cohort to be the large family of toxin clostridial. Because of similarities of these toxins with others, researchers have classified them as the family of large clostridial toxins (LCTs).
Read more about this topic: Clostridium Difficile Toxin B
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