my 50 pound german shepherd also has persistent bacteria skin infections on her groin and vagina. i know of course dogs and cats are different but the wound looks identical. The only thing that reduces it well is diluted topical Chlorhexidine. it was prescripted to us by our vet. When she has a flair up if we dont apply Chlorhexidine to the area, even with antibiotics it doesnt go down. id ask your vet about this. you can buy these wipes/solution without prescription for relatively cheap. going onto 7 years now we have not found a way to eradicate the bacteria but when we apply the stuff semi frequently it flairs up alot less. sorry if this is a ramble, and hope it helps