Bill,
You are doing the right thing by being concerened, but just don't over react.
I assume since you are planning to add supers that the hives are healthy and have no visable sign of foulbrood. If this is the case, I would treat them by dusting with
terramycin and powdered sugar.
If you really want to be certain, there is now a test kit for
AFBThere is no advantage to burning just some of your equipment. If you do have it, ALL your equipment is contaminated. Just remember, you can spread AFB from hive to hive with your hive tool.