If you go to your local tack store you can buy products especially made to kill the certain bacteria. I bought some and I'm tesitng it out. I was putting vinager and babyoil mixture and spraying it on but getting no results. So I'm trying this and I'm crossing my fingers, today my horse let us get a really good scrub on it, last couple of weeks have been rough. Today we had to twitch her (tear I hate doing it!) but we were able to really clean it and have lots of scrubbing and put lots of stuff to help kill it
I know the company that makes the product is called a horsemens dream. I'm not too sure what the product is actually called!
Good luck with curing it!