I used commercial seed starting soil in January or February, and had some very tiny mushrooms grow in one of the pots! I guess it wasn't totally sterile. Maybe I can find the picture I took...
I watched some YouTube videos that recommended a person soak the commercial sterile potting soil in boiling hot water for about 30 minutes, or something like that, just to kill off anything that might have contaminated the potting soil after it was sterilized. I did that with the bag of potting soil I bought at the store and did not have any problems.
I don't think I could soak my chicken run compost in boiling hot water to sterilize it. I think it has to be cooked at temperatures high enough to kill everything.