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
6µg/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.