Scarlet fever is associated with which toxin or toxin-producing organism?

• A. Cutaneous anthrax
• B. Diphtheria
• C. Impetigo
• D. Scarlet fever

Answer: (D)

Scarlet fever is caused by pyrogenic (erythrogenic) exotoxins produced by group A Streptococcus, specifically Streptococcus pyogenes. These toxins act as superantigens, triggering a strong inflammatory response that leads to the distinctive diffuse red rash and fever, along with the characteristic “strawberry tongue.” The disease isn’t due to the bacteria alone; it’s the toxin they produce that drives the rash. For other options, the toxins involved are from different organisms—anthrax toxins from Bacillus anthracis, diphtheria toxin from Corynebacterium diphtheriae—while impetigo is a superficial infection not defined by a toxin-mediated syndrome. The key association is that scarlet fever stems from erythrogenic toxin produced by Streptococcus pyogenes.