How do I use this regex with grep?

I'm new to regex and found a command on a regex tutorial/test site that will allow me to search for 3 consecutive consonants. The only problem is I can't figure out how to use it with grep. Would someone help me out? I'm trying to search a word list text file using: (?:([bcdfghjklmnpqrstvwxzy])(?!.{1,2}\1)){3}