Final answer:
Exotoxins are virulence factors that specifically target the intestines and are secreted by gram-positive and some gram-negative bacteria. They can be grouped into three classes based on their molecular mechanisms of action. Examples of toxins within each class are cholera toxin, phospholipases, and toxic shock syndrome toxin.
Step-by-step explanation:
Exotoxins are virulence factors that target the intestines. They are proteins secreted mainly by gram-positive bacteria and some gram-negative bacteria. Unlike endotoxins, exotoxins are specific in their action and interact with specific cells through unique molecular mechanisms.
Exotoxins can be grouped into three classes: intracellular targeting, membrane disrupting, and superantigens. Each class targets specific receptors on specific cells and causes damage through different molecular mechanisms.
Examples of well-characterized toxins within the three classes include cholera toxin, which causes intracellular targeting; phospholipases, which cause membrane disruption; and toxic shock syndrome toxin, which is a superantigen.