Acceptable treatment for open MRSA abscess

Patient: I have CA-MRSA and a few days ago developed a cellulitis spot which then abscessed and, as of today, opened. I do not have a PCP because of insurance issues and, aside from going to the local ER, have no way to get a prescription for doxycycline or sulfamethoxazole. I do, however, have a tube of mupirocin ointment. What I need to know is if it is safe to apply the ointment to the open abscess, which has such a tiny opening that it cannot be seen unless you are REALLY CLOSE, or do I have to go to the ER for oral antibiotics?

Doctor: