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Tuesday, March 29, 2016

Antibiotic-Resistant Bugs Threaten Pets and Owners

Some of you may be familiar with the acronym "MRSA" (pronounced mer-sah). It stands for Methicillin-Resistant Staph Aureus. MRSA is a bacteria which is resistant to most antibiotics, and people who get it can die from it. However, people can carry the bacteria and have no symptoms at all; it's usually folks who are compromised in some other way (very old, pre-existing illnesses, immune-suppressive medications, etc...) who could be in trouble if they contract a MRSA infection.

Dogs and cats are not typically infected with MRSA, although they can, rarely, be carriers. In those rare cases, they usually are carrying a MRSA which they picked up from a person. So it is unlikely that you would "catch" this from your pet. And it is even less likely that a pet could get sick from a MRSA infection. Staph aureus just doesn't seem to like pets.

However, we are starting to see resistant bacterial infections more and more in our dog and cat patients. In these cases, the culprit is usually a different species of Staph, called Staph pseudintermedius. When this bug becomes resistant, it goes by the acronym "MRSP" (Methicillin-Resistant Staph Pseudintermedius). We see these infections most frequently on skin or in wounds, and they are extremely difficult to cure. Usually they require intense topical therapy (medicated baths, sprays, creams, etc...) and expensive, high-powered antibiotics, not to mention the cost of expensive culture tests. It is a nightmare for the owner, the veterinarian, and most of all, the pet. It is important to note, however, that MRSP is usually not infectious to people, just like MRSA is not infectious to pets.

Like in human medicine, veterinarians have a responsibility to do everything possible to reduce the threat of these resistant "bugs". To do that, we must recognize how they become resistant in the first place. Usually it is due to inappropriate use of antibiotics. This includes:

1. Inadequate duration of antibiotic therapy. If you don't give antibiotics long enough, you may kill most of the bacteria (enough so your pet appears cured), but the ones which are left behind are the most resistant ones. The next infection will be the offspring of these resistant bacteria, and will be much tougher to cure. So always give ALL antibiotics until they're gone, even if your pet is better after just a few doses.

2. Using "big gun" antibiotics when they're not needed. We have some really great antibiotics at our disposal, and it's tempting to use these a lot because they are likely to work. However, the more often bacteria "see" these antibiotics, the more likely they are to become resistant. When infections become resistant to our "big guns," we are in serious trouble. Veterinarians should always choose the most "narrow spectrum" antibiotic likely to work in each given situation, and leave the big guns for resistant or life-threatening infections.

3. Indiscriminate use of antibiotics.  Again, it's so tempting to give antibiotics to make clients feel better. It's also wrong. Our clients love antibiotics. However, antibiotics are sometimes not indicated, even if our clients don't understand that. In these cases, antibiotics will not do anything other than to give the bacteria which might normally be carried by the pet a chance to become resistant. Here are three very common examples: a. Viral upper respiratory infections in cats. Because they are viral, not bacterial, antibiotics will not help. b. Ear infections. These are often caused by yeast. The only way to know is by looking under a microscope at the organisms taken from the ear. If there is a yeast infection, antibiotic ear medicine is the wrong thing to use. But we get phone calls every day wanting us to prescribe an antibiotic ointment for someone's pet who doesn't want to bring the pet in. c. "Cystitis" in cats. Young cats often get a condition that looks a lot like a bladder infection. There is blood in the urine and discomfort when urinating. Without doing a culture, the condition is indistinguishable from an actual bladder infection. Cultures are expensive, and we know that statistically over 95% of cats under the age of ten with these symptoms do NOT have an infection, so I rarely prescribe antibiotics for young cats with these symptoms.

In all the cases mentioned above, the use of antibiotics can contribute to an increasingly-resistant population of bacteria, and that's bad news for all of us.

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