Some ingredients are more high-risk than others when it comes to bacterial growth. Mayonnaise, eggs, and meats are all prime targets for salmonella and other nasty bugs. On the other hand, peanut butter and jelly sandwiches are relatively safe, since they don't contain any high-moisture ingredients. But, let's not get too comfortable – even PB&J can go bad if left out for too long.
The type of bread you use can also make a difference. Whole grain bread is generally more resistant to bacterial growth than white bread, since it contains more antioxidants and fiber. So, if you're planning to leave your sandwich out for a while, consider using a hearty bread that can stand up to the test. And, of course, always wash your hands before handling food – it's just common sense.
Refrigerated Pb&J Sandwich Shelf Life: How Long Does It Last? | CyCookery
