Question:hard
The pathogenesis of which one of the following infections does NOT occur mainly through an exotoxin?
The pathogenesis of which one of the following infections does NOT occur mainly through an exotoxin?
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Ask which organism's everyday infections are explained more by invasion and inflammation than by a single circulating toxin.
Updated On: Jul 16, 2026
- Staphylococcus aureus
- Escherichia coli
- Clostridium botulinum
- Streptococcus pyogenes
Show Solution
The Correct Option is D
Solution and Explanation
This question is answered by asking, for each organism, whether the toxin itself is the main driver of disease or whether invasion and inflammation are doing most of the work.
- Staphylococcus aureus: wrong choice — toxic shock syndrome, food poisoning, and scalded skin syndrome are all textbook exotoxin-mediated diseases.
- Escherichia coli: wrong choice — diarrheagenic strains cause disease chiefly through heat-labile/heat-stable enterotoxin or Shiga-like toxin.
- Clostridium botulinum: wrong choice — botulinum toxin alone reproduces the full disease, the purest example of exotoxin-mediated pathogenesis.
- Streptococcus pyogenes: correct — its routine infections like pharyngitis and cellulitis are driven mainly by tissue invasion and inflammation via M protein and enzymes, not by a single dominant exotoxin.
Correct answer: Streptococcus pyogenes.
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