Staph. aureus causes vomiting in 16-18 hours. The mechanism of action is –
**Core Concept**
Staphylococcus aureus food poisoning is a classic example of a toxin-mediated illness, where the bacteria produce a toxin that causes symptoms. The toxin responsible for this condition is a heat-stable exotoxin that acts on the gastrointestinal tract.
**Why the Correct Answer is Right**
The correct answer is related to the mechanism of action of the toxin produced by Staphylococcus aureus. The toxin, known as enterotoxin, works by binding to the enterotoxin receptor on the epithelial cells lining the small intestine. This binding triggers a cascade of events, including increased permeability of the cells, leading to the release of histamine and other mediators. The increased permeability and mediator release cause the symptoms of vomiting, diarrhea, and abdominal cramps.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not describe the mechanism of action of the toxin produced by Staphylococcus aureus. While the toxin does affect the gastrointestinal tract, it is not a direct result of bacterial invasion or adhesion.
**Option B:** This option is incorrect because it refers to the mechanism of action of a different type of toxin, such as those produced by Clostridium difficile or Shigella dysenteriae. These toxins work through different mechanisms and are not responsible for the symptoms of Staphylococcus aureus food poisoning.
**Option C:** This option is incorrect because it refers to the mechanism of action of a different type of toxin, such as those produced by Clostridium perfringens. These toxins work through different mechanisms and are not responsible for the symptoms of Staphylococcus aureus food poisoning.
**Clinical Pearl / High-Yield Fact**
The symptoms of Staphylococcus aureus food poisoning typically occur within 1-6 hours after ingestion of contaminated food, but in some cases, they can occur as late as 18 hours. This delayed onset is often due to the toxin's ability to persist in the gastrointestinal tract for an extended period.
**Correct Answer:** B. Staphylococcal enterotoxin binds to enterotoxin receptors on the epithelial cells, increasing permeability and leading to the release of histamine and other mediators, causing vomiting, diarrhea, and abdominal cramps.