Advice to owners
Advise owners of pets with MRSA of the potential for zoonotic transmission (Figures 4A & 4B). Although the risk of clinical disease is probably low for immunocompetent people, reports of community-acquired MRSA in
immunocompetent people are on the rise.2 Additionally, the concern for transmission is greater if a pet is exposed to immunosuppressed people or when household members
are in contact with higher-risk people (i.e. healthcare workers).3 Involvement of physicians in these cases is prudent because veterinarians should not make specific recommendations for preventing
or diagnosing disease in people.
Figure 4A. A cat with methicillin-resistant deep pyoderma (MRSA) secondary to facial pruritus and self trauma due to food
allergy. Note that the owner is not wearing gloves and has been topically treating this wound for several months.
Figure 4B. After six weeks of systemic antibiotics based on bacterial culture and sensitivity testing, the wound has completely
Also advise owners of pets with MRSP and MRSA infections that, for most pets, the prognosis for cure is good with appropriate
therapy and monitoring and, in cases of recurrent skin or ear infections, if the underlying cause is identified and addressed
As discussed in last month's article, some animals are not infected with but instead are colonized with—or are carriers of—methicillin-resistant
staphylococcal strains. Management recommendations for pets colonized by methicillin-resistant staphylococcal bacteria are
unclear, but most references recommend practicing good hygiene (washing hands or using hand sanitizer frequently after touching
the pet, not allowing a pet to lick or sniff at people, frequent washing and disinfection of pet bedding and housing surfaces)
and isolating colonized or infected pets from immunocompromised people and pets.
Figure 5. An atopic dachshund with lichenification and infection of the ventral tail caused by MRSP.
Systemic antibiotics are not recommended to eliminate colonization. Topical antimicrobial shampoos and conditioners (i.e. those containing chlorhexidine) may be helpful but have not been specifically studied in animals. In one study in people,
chlorhexidine bathing and intranasal mupirocin application in a 16-bed intensive care unit caused a 48% decrease in MRSA colonization
and infection.6 However, topical use of mupirocin in the nasal cavity is unlikely to be successful as monotherapy in MRSA-colonized pets—as
studies have shown identical MRSA carriage from the nares, mouth, anus, groin, and head.7
Mucosal carriage of S. pseudintermedius was shown to be significantly decreased in healthy dogs when fusidic acid was applied to the eyes, nostrils, anus, and vulva.8 However, in the absence of any controlled studies on spontaneous decolonization and long-term efficacy of antibacterial
therapy for decolonization, it remains controversial whether decolonization of animals is necessary or warranted. If this
measure is under consideration, it should involve collaboration between and advice from veterinary and medical infection-control
experts and would need to include all in-contact people, in-contact animals, and their environments.1