However, Staphylococcus aureus infections, including MRSA and multiple-resistant strains, do occur in dogs and cats. It is not clear to what extent humans are the primary reservoir source for infection transfer to dogs and cats, or to what extent dogs and cats act as reservoirs of infection for susceptible people. In one review of the subject (Duquette and Nuttall 2004) humans were cited as being the most common source of infection for dogs and cats.
The reported isolation rate of methacillin-resistance Staphylococcus aureus from normal dogs and cats also varies from 93/6519 (1.42%) in domestic animals (Rich and Roberts 2004), to 3/148 (2.03%) cats (Lilenbaum et al 1998).
The occurrence of methicillin-resistant strains of Staphylococci (not just S.aureus) increases in the presence of disease, and in one study 15/40 dogs with recurrent pyoderma were infected with methicillin-resistant bacteria (Frank et al 2003). In another study 23/25 methacillin-resistant Staphylococci (9 of which were MRSA) isolated from dog wounds or skin lesions possessed the mecA gene, which has been linked to methicillin-resistance in human infections.
In one study, 5/5 patients with MRSA infected wounds that were tested grew MRSA positive cultures when they had a swab taken from their nasopharynx (Boag et al 2004)
Breed Occurrence And Other
The relative importance of these factors, and the significance of human or pet contact with Hospital premises is unclear.
Susceptible members of staff should consider themselves at risk of contracting MRSA from their patients, and take precautions to prevent such cross-infection
Strict hygiene controls should be employed on veterinary premises, especially in surgical areas with respect to instrumentation sterilisation and handling, and wound management to minimise the risk of post-operative wound infection.
Unnecessary intimate contact between veterinary staff and patients which might facilitate the transfer of bacteria from skin or nasal cavities should be discouraged.
The rational use of antibiotics is important to minimise the risk of further drug resistance developing.
Culture and Sensitivity
The diagnosis of MRSA infections needs to be carried out in an experienced laboratory and care needs to be taken when interpreting results. For example, specific broth or agar plate culture techniques are preferred to Kirby-Baur disc techniques because of different specificities and sensitivities, and the latter techniques over-estimate methicillin resistance.
During sample collection and investigation care MUST be taken to avoid :
PCR is used to identify the presence of the mecA gene.
Patients infected with MRSA can be treated with alternative antibiotics, based upon culture and sensitivity findings. For example , one case of joint infection following elective cranial cruciate repair was successfully treated by surgically inserting an absorbable gentamicin-impregnanted sponge (Owen MR et al 2004)
There are also reports of transmission of MRSA from animals to humans. A cat was implicated as a reservoir of MRSA for the re-infection of humans in a geriatric ward (Scott et al 1998) and carrier dogs have been implicated as a reservoir for the infection of people in family homes (Cefai et al 1994; Manian 2003)
Boag A, Loeffler A, and Lloyd DH. Methicillin-resistant Staphylococcus aureus isolates from companion animals. Veterinary Record (2004) 154: 411
Bradshaw SE . Endocarditis due to Staphylococcus aureus after a minor dog bite. Southern Medical Journal (2003) 96: 407-9
Cefai C , Ashurst S and Owens C. Human carriage of methicillin-resistant Staphylococcus aureus linked with pet dog. Lancet (1994) 344:539-540
Duquette RA and Nutall TJ. Methicillin-resistant Staphylococcus aureus in dogs and cats : an emerging problem ?. Journal of Small Animal Practice (2004) 45:591-7
Manian FA. Asymptomatic nasal carriage of mupirocin-resistant methicillin-resistant Staphylococcus aureus in a pet dog associated with MRSA infection in household contacts. Clinical Infectious Disease (2003) 36: E26-E28
Owen MR, Moores AP and Coe RJ. Management of MRSA septic arthritis in a dog using a gentamicin-impregnated collagen sponge . Journal of Small Animal Practice (2004) 45: 609-612
Rich M and Roberts L . Methicillin-resistant Staphylococcus aureus isolates from companion animals. Veterinary Record (2004) 154: 310.
Scott GM et al. Cross-infection between animals and man : possible feline transmission of Staphylococcus aureus infections in humans ? Journal of Hospital Infection (1998) 12:29-34
Simoons-Smit AM et al. Transmission of Staphylococcus aureus between humans and domestic animals in a household. European Journal of Clinical Microbiology and Infectious Diseases (2000) 19: 150-2
Tomlin J et al. Methicillin-resistant Staphylococcus aureus infections in 11 dogs. Veterinary Record (2004) 144: 60-64
Updated October 2013