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MRSA - What the "Superbug" Could Mean for Your Pet |
MRSA – What the “Superbug” could mean for your pet
We are hearing more and more about the existence of “superbugs” that are resistant to many antibiotics. MRSA, which stands for “Methicillin Resistant Staphylococcus Aureus”, is one of these superbugs. Under normal conditions, Staphylococcus aureus (abbreviated S. aureus), is relatively harmless and is found on and in healthy humans and some animals. S. aureus is what is known as an “opportunistic pathogen”, meaning that it will take advantage of any opportunity, such as weakened defenses, to cause disease in its host. The reason that S. aureus presents problems is that it is readily able to develop resistance to antibiotics; it has long been resistant to penicillin, and in recent years, some strains (the MRSA strains) have developed a resistance to Methicillin. Methicillin is one of the more powerful antibiotics in use today, and the fact that some S. aureus is resistant can make it challenging for doctors and veterinarians to treat infections with this resistant organism.
MRSA is widespread, and is often referred to in medical literature as “community associated MRSA”. MRSA infection has become a serious problem in humans, and although animal cases are still rare, they are on the rise. It can colonize animals or people in several body sites, usually areas that are moist. In people, colonies of MRSA have been found in the nasal passages, the throat, the armpits, around the rectum, in the intestinal tract, and on the skin, often found under the fingernails or between the fingers. In dogs, the main sites of colonization appear to be the nasal passages and the intestinal tract. MRSA has also been identified in horses. There are few published reports of MRSA colonizing other domesticated pets. Pets can become colonized by close physical contact with colonized owners, and vice versa, or they can become colonized from other pets or the environment. A healthy animal or person that is colonized with MRSA is not sick, but does harbour the bacteria. Colonized animals or people are at a higher risk of developing an MRSA infection if their immune system becomes compromised, or if they suffer a wound or other injury.
MRSA only becomes a problem when it enters the body, often through a wound. When MRSA causes an infection, the invaders grow rapidly, producing toxins that damage the surrounding tissues. Most reported cases of MRSA infection in dogs are associated with prolonged surgical procedures that subsequently become infected. This appears to parallel the situation in humans, many of whom have developed the infection during or after a hospital stay.
If an infection with MRSA occurs, it is important to treat this potentially life-threatening infection aggressively. Currently, most strains of S. aureus, even MRSA, remain susceptible to some antibiotics, such as sulphonamides. Ideally, before treating any infection, samples should be taken and submitted to a bacteriology laboratory for identification and sensitivity testing. In this way, bacterial infections will be treated appropriately, MRSA infections will be identified rapidly, and the prognosis for recovery will be greatly improved.
If other pets or family members are healthy, there is no reason to separate them from an infected person or animal. Only those that are ill, with compromised immune systems, are at risk of a severe MRSA infection. In the environment, MRSA is readily controlled by sanitation, and will be destroyed by most disinfectants if they are used properly. Good overall cleanliness will do much to reduce the environmental risks, although it will not prevent exposure to carriers of the organism.
You should not become alarmed if your pet is diagnosed with a routine “staph infection” or with “staphylococcal dermatitis”. This is because the common cause for a staphylococcal infection in dogs is Staphylococcus intermedius, not S. aureus, and S. intermedius does not appear to develop resistance as readily.
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