What you need to know regarding methicillin-resistant Staphylococcus aureus (MRSA) - DVM
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What you need to know regarding methicillin-resistant Staphylococcus aureus (MRSA)

DVM InFocus


Clinical diagnosis of MRSA infection involves isolation of S. aureus that is resistant to oxacillin from an infected body site. Microbiological analysis samples should be collected from pets with nonhealing wounds and nonantibiotic-responsive or nosocomial infections. In veterinary medicine, it is important for laboratories to differentiate S. aureus from S. intermedius since S. intermedius is more common in dogs and cats. Although methicillin-resistant S. intermedius has been reported in both animals and people, it rarely poses a public health threat. The Clinical and Laboratory Standards Institute (CLSI) recommends the use of the cefoxitin disk diffusion test, the PBP2a latex agglutination test, or a plate containing 6g/ml of oxacillin in Mueller-Hinton agar supplemented with sodium chloride to screen for MRSA. Polymerase chain reaction (PCR) may also be used to detect the presence of mecA to confirm that S. aureus isolates are indeed MRSA.


While there is a wealth of literature dealing with the control and prevention of MRSA transmission in people, there is very little corresponding information regarding animals. Hand hygiene is an integral part of preventing the spread of MRSA between people, and it's likely to be an integral part of controlling the spread between people and animals or between animals through people. After contact with any hospitalized person or any animal, hands should be washed thoroughly. Alcohol-based hand sanitizers are also effective as recommended. Strict attention to cleaning and disinfection of animal contact areas may discourage colonization or infection. Designated instruments such as thermometers, leashes, and collars may be used for those animals suspected of having MRSA infection or colonization. Since MRSA is carried in the rectum, disposable thermometer covers are recommended. Barrier nursing precautions, such as wearing gloves, disposable clothing or clothing that can be appropriately laundered, and using protective masks and eyewear are advocated when in contact with wounds or other body fluids that may be infected with MRSA. Within a colonized or infected pet's household, restricting high-risk contact (e.g., mucosal-to-mucosal contact) is indicated, in addition to preventing contact of colonized animals with high-risk people, such as those with a compromised immune system. Although there is no direct data to support it, avoiding close contact, such as sleeping on the same bed or sitting in the lap when either the pet or the person has a known MRSA infection, seems reasonable. Individual veterinary hospitals may choose to screen incoming cases for infection or colonization at the time of admission. A similar screening process is used in some, but not all, human hospitals. Where strictly enforced, such screening programs have dramatically cut the incidence of MRSA infection. If a colonized or infected animal is identified, quarantine may be performed either throughout hospitalization or at least until a negative culture status is achieved. Additionally, once admitted, all suspect cases of MRSA infection may be quarantined and nursed using barrier nursing precautions. At the Ontario Veterinary College, specific guidelines for suspected MRSA-infected patients are enforced. When arriving at the veterinary hospital, the animal with suspected or confirmed MRSA must wait in the car until the owner has checked in. Then, the animal is immediately taken to a consultation room. After discharge, all cage items, examination rooms, and medical equipment are disinfected. If appropriately used, disinfectants effective against other staphylococci are most likely also effective against MRSA.


Source: DVM InFocus,
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