br br If you have a weak immune system because of an existing condition or treatment, you may have a higher risk of bacterial gastroenteritis. The risk also increases if you take drugs that decrease stomach acidity. br br Handling food incorrectly can also raise your risk of bacterial gastroenteritis. Food that’s undercooked, stored too long at room temperature, or not reheated well can aid in the spread and survival of bacteria. br br Bacteria can produce harmful substances known as toxins. These toxins can remain even after reheating food.