Cleaning safe space

Hi, I’ve just joined this because I really don’t know what to do. My 21 year old son spends a lot of time in his bedroom but won’t let me in to clean it, he has germ phobia which doesn’t really make alot of sense considering the topic but his is more around food. He doesn’t clean anything himself and wears gloves to touch anything outside his room.  I’ve tried different ways of getting the message across but nothing has worked. Any suggestions? Pray thanks.