Can bacteria survive microwaves (as in a microwave oven)?
It's the heating effect of microwaves that kill bacteria, not the microwaves themselves. Whether bacteria survive depends on how long you heat your food and at what temperature. The core temperature of cooked food should be at least 60 degrees C. Higher (70 - 75 degrees C) is even safer, especially if you've only reheated an item for a couple of minutes.
With microwave ovens, it's important to make sure food is evenly cooked, so read your appliance instructions about stirring and positioning food items correctly.
Remember that if food has already gone off, it will likely contain toxins produced by microbes in the food, and these can still remain in the food and make you sick even if you heat it and kill the microbes.
- Olivia Rose-Innes, EnviroHealth Editor, Health24, April 2012