Treatment of infections in animals should be based on in vitro culture and sensitivity results in combination with patient
and drug factors, such as concentration at the site of infection and drug penetration. Treatment success for skin infections
also depends on the identification and treatment of any underlying dermatoses such as allergies, autoimmune disease, endocrinopathies,
and keratinization defects.
Based on antibiotic therapy of MRSA in people, a reasonable choice for initial treatment of pets with suspected MRSA would
be trimethoprim sulfonamide drugs. Resistance can emerge quickly to fluoroquinolones, making them a poor first option for
therapy. While clindamycin susceptibility is commonly identified in vitro, inducible resistance may be present with certain
MRSA isolates (especially those that are erythromycin-resistant). Therefore, in erythromycin-resistant strains, clindamycin
should be avoided unless testing for inducible resistance has been performed. Ideally, antimicrobials such as vancomycin that
are used in critically ill people should be avoided unless the animal has a life-threatening infection that is resistant to
all other treatments. Some superficial infections may be treated topically with antimicrobials or antiseptics. Topical agents
may be used for wounds or skin infections and may include silver sulfadiazine, fusidic acid, mupirocin, or a combination of
1 percent silver sulfadiazine and 0.2 percent chlorhexidine gluconate. Other topical treatments to consider include chlorhexidine
alone, 1 percent acetic acid, allicin (garlic extract), and tea tree oil.
Superficial pyoderma in dogs should be treated for a minimum of three weeks (at least one week beyond clinical resolution)
and deep pyoderma should be treated for a minimum of six weeks (at least two weeks beyond clinical resolution). Some infections
of deep interdigital pyoderma or acral lick granulomas may require therapy for three months or longer. For best results, bacterial
culture and sensitivity testing should be performed at the start of therapy and owners should be counseled to finish the entire
course of antibiotic therapy.
Successful treatment of MRSA infection is possible, but depends upon early recognition, appropriate antibiotic usage (including
correct dosage and duration), and identification and treatment of underlying dermatologic conditions. In general, knowledge
of MRSA is extremely relevant for veterinarians who are called upon not only to attend to animal diseases, but also to aid
in prevention of zoonoses.