Any cattle in your area?
A quick google search suggests it is common in cows (mastitis) and in musk deer it can cause abscesses.
Looks like it has developed resistance to both tetracycline and erythromycin.
Here is a good article:
Looks like penicillin is the way to go!
I would ask the vet about chlorhexidine skin cleaner to try and kill bacteria on the outside of the skin?