Forget the Antibiotics for acne. Most of the time, it is caused by a common mite which survives off of hormone secretions in the pores of skin esp. around the face. Some people are extra sensitive to them because of their genetic make-up. Everybody has 'em, but not everybody reacts to them. They are called DEMODEX mites.
There are special shampoos, and medicated cleansers for these things.
There are also methods for killing them off, and keeping them away.
You will have to do some googling on the subject.
Shroom