Sarcophagus, two things come to mind. As a matter of fact, they virtually sprung into my mind the moment I read your post.
For your upper arms, might I suggest the application of heat via heat packs, water bottles etc. Bacteria are generally fragile little creatures and a mild increase in temp may keep them at bay.
Also, you could experiment with ingesting different combinations of pro biotics, sort of crowd the little buggers out, so to speak.
