Staph infection on the mouth

A friend of mine was diagnosed with a staph infection on the side of his mouth. I was wondering how he could have gotten this, he hasn't had any injuries or been in the hospital, and he doesnt have hiv. Could he have contracted this from kissing or giving oral? I heard that staph can live in the groin area, is it possible to catch staph from the groin area if he didnt have any open wounds? Could he catch staph from kissing someone who had a staph infection? How could he have contracted this infection on the side of his mouth?

Impetigo is common as dirt, especially as the weather warms, and I'm guessing it isn't an oral infection at all but just near the corner of the mouth, perhaps as with perleche.