Listeria evolved to live in your fridge

http://www.thebeerbarrel.net/showthread.php?7421-Listeria-evolved-to-live-in-your-fridge

Cold cuts are pretty much delicious little hostels for listeria—a bacteria that can cause serious food poisoning, and even kill vulnerable populations like babies, the elderly, and the sick. That's why doctors advise pregnant women to not eat them, and why the CDC suggests that older people reheat their "cold" cuts to 165 degrees before eating them.
But I've long wondered: Why are listeria able to get such a foothold on a food product that's already been cooked, and that is generally stored in refrigerators? Shouldn't those two factors impede bacterial growth?