Recently, two different drug companies have released very similar topical products for the treatment of ear infections in dogs. Both products contain an antibiotic called chloramphenicol. We consider chloramphenicol to be a “big gun” antibiotic and are encouraging its use be reserved only for infections documented by culture and sensitivity testing to be highly resistant to more baseline antibiotics. The nice feature of both products is they are applied by the veterinarian after a thorough ear flush. The pet parent does not need to treat the infection at home because the liquid medication remains in contact with the infection for a prolonged period of time. Routine follow up is a must to ensure all infection is resolved.
A few points about resistant strains of bacteria:
- Becoming increasingly more common in pets.
- We don’t know exactly what has caused the increase of infections with these resistant strains of Staph. We do know that resistant bacteria contain genes coding for the resistance and must share those genetics with other bacteria in order to convey resistance.
- Dogs and cats carry a strain of staphylococcus named Staph pseudintermedius while humans carry Staph aureus.
- Suspicion for a resistant strain of staph rises when a patient is receiving appropriate antibiotic therapy yet the infection is not clearing.
- Testing involves collecting a swab sample from bacterial lesions which is submitted to an outside lab. The lab grows the bacteria and then test the bacteria against a variety of antibiotics to see which will kill the bacteria. This is called a culture and sensitivity (C/S) test.
- We advocate for topical antimicrobial therapy (shampoo, spray, cream or solution) while we are waiting for C/S results.
- We also advocate for topical antimicrobial therapy when an infection is mild, or localized to one area (face folds for example) or only involves limited areas on the body.
- These bacteria are considered opportunistic pathogens, meaning they simply take advantage of an underlying condition in the skin/immune system and overgrow. Some examples of predisposing factors: allergic skin disease, low thyroid function, or over production of steroids by the adrenal glands. There are also certain breed characteristics[i] that may predispose a pet to infection: skin folds such as pugs and bulldogs, pressure calluses and thick coated long-haired breeds prone to dermatitis such as Golden Retrievers, just to name a few.
- If systemic antibiotics can be avoided for several months in a row it is possible for the bacteria to lose the genes for resistance and return to being “easy to treat” with first line antibiotics.
- A great resource for more information is the worms and germs blog athttp://www.wormsandgermsblog.com/articles/diseases/mrsamrsp/
[i] Hoet, AE, Van Balen JC. Understanding the Epidemiology of Environmental Methicillin Resistant Staphylococci in a Dermatologic Service. Proceedings of the North American Veterinary Dermatology Forum, 2015.