Anything that could live in 80 proof alcohol won't just infect your beer, it'll blow up your car, steal your wife, teach your dog to attack you, and force your favorite sports teams to lose every game. Not only that, but it will be rich, and better looking than you.
In other words, don't worry about it. No need to pasteurize your bourbon before adding it.
Dammit, Skins. You snuck in there while I was composing!