Toxins are poisonous or venomous substances especially produced or derived by certain microbes (pathogens) that can cause disease or even death. There are two kinds of toxins- endotoxins and exotoxins.
Exotoxins are a kind of proteins that are secreted by bacteria. These proteins might be enzymatic in nature. They are poisonous and, thus, can cause damage to the host cells. They are produced inside the cell. Exotoxins are called so because they cause damage only when they are released out of the cell. They vary in toxicity or the degree of harmfulness. Many exotoxins have targets of action. For example- cytotoxins, enterotoxins and neurotoxins.
Enterotoxins are a specific kind of exotoxins that affect the gastro-intestinal mucosa or lining. They can cause vomiting, diarrhea and various types of food poisoning. Most enterotoxins are produced by the bacterium Staphylococcus, but other bacterial species like Escherichia, Bacillus and Clostridium also produce enterotoxins.