Clostridium difficile toxin A

Clostridium difficile toxin A (TcdA) is a toxin generated by Clostridioides difficile, formerly known as Clostridium difficile. It is similar to Clostridium difficile Toxin B. The toxins are the main virulence factors produced by the gram positive, anaerobic, Clostridioides difficile bacteria. The toxins function by damaging the intestinal mucosa and cause the symptoms of C. difficile infection, including pseudomembranous colitis.

TcdA is one of the largest bacterial toxins known. With a molecular mass of 308 kDa, it is usually described as a potent enterotoxin, but it also has some activity as a cytotoxin. The toxin acts by modifying host cell GTPase proteins by glucosylation, leading to changes in cellular activities. Risk factors for C. difficile infection include antibiotic treatment, which can disrupt normal intestinal microbiota and lead to colonization of C. difficile bacteria.