Last week I saw two patients with Staph infections. Finding a Staph infection is not unusual; veterinarians see Staph infections every day because Staphylococcus bacteria are normal inhabitants of the skin of dogs. Staph infections start like this: your dog scratches, breaks the skin and the Staph slip in and cause an itchy infection in the hair follicle called pyoderma. Staphylococcus psuedintermedius is one of the resident bacteria in the skin of dogs and a common cause of pyoderma. Staphylococcus aureus is the analogous human bacteria. When either of these bacteria acquires resistance to an antibiotic called methicillin, they have been branded “superbugs,” and in medical terms are called methicillin resistant Staphylococcus psuedintermedius (MRSP) or Staphylococcus aureus (MRSA). Just because they have the name superbug, doesn’t mean the infections caused by these bugs are not treatable; they are not successfully treated with the typical antibiotics we use for a “normal” Staph infection.
Originally, MRSA/MRSP infections occurred in hospitalized human or animal patients, but recently MRSA infections have been found in patients who have never been in the hospital. This type of MRSA/MRSP infection is often called community acquired. Hospital acquired methicillin resistant infections can readily be transmitted from patient to patient in the hospital, and preventing transmission is one reason veterinarians and physicians wash and sanitize their hands between patients.
Infections with methicillin resistant bacteria may be becoming more widespread. Recently reports indicate wild rats can be carriers of MRSP and a baby alpaca was found to be colonized with MRSA. Obviously, these animals did not acquire the infection in the hospital.
Pets with the superbug
In studies testing a large number of dogs and cats for MRSP, less than one percent of animals screened carried these bacteria. This week’s first patient with MRSP developed a bladder infection confirmed via a urine culture to be MRSP. Neither she nor anyone in her family has been hospitalized, but she has recently completed a course of chemotherapy for a mast cell tumor and possibly the infection is related to those treatments. Happily, the test results indicated a common antibiotic will be effective in treating the infection.
People to pets?
The healthy pets living with humans infected with MRSA have been tested and some found to carry the MRSA which appears to be the same in both the pet and the human. In this interesting study, dogs, cats and even a hamster living with a human infected with MRSA were found to carry MRSA.
Whether the pets were the source of the infection or simply accidently infected by the human is unknown. Nevertheless, this study shows pets could be a source of infection or reinfection for their human family members.
Last week’s second patient with a Staphylococcus psuedintermedius infection did not have a methicillin resistant one, but she could have. Angel is a therapy dog who visits hospitals. Because of her occupational risk, we tested her to protect not only her health, but the health of those under her care.
What can a pet owner do?
If your veterinarian recommends a culture of your pet’s skin or urine, I strongly recommend you agree to the test to help determine the best course of treatment and to identify MRSA/MRSP early.
If you have a therapy pet, follow the guidelines set out by your therapy pet group to protect your pet, yourself and your patients.
If your pet has an infection, tell your veterinarian if someone in your family has recently been hospitalized or diagnosed with MRSA. This information is critical when we submit tests to the lab and prescribe antibiotics.