What are the two major toxins produced by Clostridioides difficile and their role in disease?

• A. Enterotoxin alone causing secretory diarrhea
• B. Toxins A (enterotoxin) and B (cytotoxin) causing disruption of cytoskeleton and pseudomembranous colitis
• C. Alpha and beta toxins causing gas gangrene
• D. Tetanus and botulinum toxins causing neuroparalysis

Answer: (B)

Two toxins drive Clostridioides difficile disease: a secretory enterotoxin and a cytotoxin that damages the mucosal cells. Toxin A acts mainly as an enterotoxin, promoting water and electrolyte loss and attracting inflammatory cells, which contributes to watery diarrhea and mucosal irritation. Toxin B is a cytotoxin that glucosylates Rho family GTPases, causing disorganization of the actin cytoskeleton, cell rounding and death, and disruption of tight junctions. This cytotoxic action leads to extensive mucosal injury and the characteristic pseudomembranes seen in pseudomembranous colitis. Together, these toxins cause the inflammation, diarrhea, and colonic damage that define C. difficile infection, with toxin B playing a key role in tissue injury while toxin A contributes to secretion and inflammation. Other options describe toxins from different organisms or oversimplify the disease by attributing it to a single toxin.