Cephalopod wounds and infections have been successfully treated in my lab and the NRCC by injecting food items with a few ccs of chloromycetin HCL. Some vets have a form of Chloromycetin for cats, but the kind you need to get comes in an injection vial as a powder that you add purified water to. Trouble is, this stuff isn't easy to come by. You will have to convince a veterinarian to write a prescription (or possibly order it for you) and then the trick is finding a pharmacy that can get it- the only one in my area (Suburban Washington DC) was a hospital. I found working the Jedi Mind Trick on my Veterinarian was easy- she was more than delighted to add an octopus to her dossier of patients.
For butt burn it worked like a charm. The gaping gash never healed up, but the infection was halted and the cuttle lived out a reasonably normal life. Cuttlfish in captivity are also prone to a cateract-like infection of the eye, which eventually leads to blindness. Cholormycetin will slow the advance of the infection, but can't seem to stop it. I had a cuttle lose sight in one eye, which severely affected it's depth perception. For the last couple month of it's life, that particular cuttlefish had to be handed it's food. It couldn't target even a dead, frozen shrimp lying on the sand.
At the NRCC, I understand that often important project animals are commonly prophylactically protected against infection with this medication.
Good Luck! Jimbo