Food poisoning is most often caused by the bacteria Staphylococcus, which produces a toxin that stays on food even when it is properly prepared. The body senses the toxin and promptly tries to rid itself of the toxins, resulting in heavy vomiting 1-2 hours after eating the spoiled food.
Many different germs can cause food poisoning, among which one of the most interesting is Bacillus cereus. B. cereus is found on many different foods, but it is commonly associated with a type of food poisoning called fried rice syndrome. It creates spores that can survive if food is not improperly cooked (as in not hot enough or cooked for long enough), as the temperatures are not high enough.
Unlike infections such as gastroenteritis where the bacteria are killed by heat during cooking, spores are quite resistant to short periods of reheating, such as microwaving. This means that if the spores were not killed when the rice was first cooked, it stays around even after refrigeration and reheating. The bacteria grow from the spore and start producing a toxin called cereulide. One to five hours later, the person who eats this tainted rice develops severe vomiting and nausea.
Fortunately, like most food poisonings, fried rice syndrome is easily treated with supportive management. The body does most of the work by decontaminating itself through vomiting. The important part is staying hydrated by keeping up with fluid loss. Most food poisoning cases resolve on their own within 24 (miserable) hours.