Sterilize a retainer?

How can I sterilize my retainer? I live in college and while i was in the bathroom, of a college dorm (it does get cleaned daily but this was at night) cleaning my retainer it fell on the floor. I washed with soap 4 times ever since but I still don't want to put it back into my mouth. I was going to try to clean it with listerine? just soak it in listerine for a few minutes then use this denture cleaner that I have to clean it one more time. Do you think this would be enough th throughly clean it?