Listeria needs several things in order to thrive and grow. The Exterminators needed to remember those things, so after meeting with a food safety specialist, we learned the funny acronym, FAT TOM. Each letter in FAT TOM stands for something Listeria (and food borne diseases in general) need to grow, replicate, and thrive.
Food - eggs, milk, meats, animal products, and sometimes fresh fruits and veggies
Acidic foods -slightly acid foods, but not as acidic as lemons or apples
Time -If you heat foods slowly from a frozen state to a cooked state, it gives listeria time to flourish at it's perfect temperature.
Temperature - listeria's prime growth temp is about 93degrees F
Oxygen - all living things need it.
Moisture - all living things need water
Food borne pathogens need all of these to live and grow. Without one of these, it might not be able to live. For instance, you usually don't find food borne diseases on crackers, because they're dry. You won't find it in a vacuum (a place where there isn't any air) because it needs oxygen.