Actually I attended the medical discussion at the Gathering (Dr Gwinn presiding) and if I recall correctly he said he carries doxy on his as a Lyme's prevention. He recommended 1-2 pills (immediately or within a week or so) after getting a tick bite. The theory being that this would be enough to kill any Lyme bug during its incubation period and prevent it from becoming full-blown Lyme's. (Don't take this as gospel -- this is from memory which could be fuzzy.)
I kinda wish I'd thought to bring up MRSA at the discussion.