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 a relatively common and harmless bacterium. It is what 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 such as penicillin. In recent years, some strains (the MRSA strains) have developed a resistance to methicillin, one of the more powerful antibiotics in use today. An infection with one of these resistant strains becomes very challenging for doctors and veterinarians to treat.
MRSA, often referred to in the medical literature as "community associated MRSA" has become a serious problem in humans. Although animal cases are still rare, reported cases are on the rise in horses and dogs. The bacteria tend to establish colonies in body sites that are moist. In people, this includes the nasal passages, the throat, the armpits, the intestinal tract, around the rectum, and on the skin, usually under the fingernails or between the fingers. In dogs, the main sites of colonization appear to be the nasal passages and the intestinal tract. A healthy animal or person that is colonized with MRSA is not sick, but does harbour the bacteria. MRSA only becomes a problem when the bacteria penetrate through the immune defenses. However, colonized people or animals serve as a reservoir or source of infection and are capable of contaminating the environment or infecting others that they come in contact with. They are also at a higher risk of developing an MRSA infection if their immune system becomes compromised, or if they suffer a wound or other injury. 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.
Once the MRSA bacteria invade the body, they grow rapidly and produce toxins that damage the surrounding tissues. 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 already ill 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.
Caution: These news items, written by Lifelearn Inc., are licensed to this practice for the personal use of our clients. Any copying, printing or further distribution is prohibited without the express written permission of Lifelearn Inc. Please note that the news information presented here is NOT a substitute for a proper consultation and/or clinical examination of your pet by our clinic veterinarian.
|
