Low-dose rifampicin for resistant staph skin infections in dogs

Abstract

BACKGROUND: Rifampicin (RFP) is a potential treatment for canine multidrug-resistant (MDR) meticillin-resistant staphylococci (MRS), yet the use of lower doses based on recent MIC data has not been evaluated in vivo. HYPOTHESIS/OBJECTIVES: To provide information on the efficacy and safety of low-dose range RFP (≤6 mg/kg/day) for the treatment of canine MDR MRS pyoderma. ANIMALS: Fifty-one client-owned dogs. MATERIALS AND METHODS: Retrospective review of dogs medical records. Dogs were from 11 US dermatology referral practices and had oral RFP at ≤6 mg/kg/day. Data evaluated included response to treatment, adverse events, and serum changes in alanine aminotransferase (ALT) and alkaline phosphatase (ALP). RESULTS: Complete resolution of pyoderma occurred in 39 of 51 dogs (76.5%). Topical antimicrobials were used concurrently in most cases (47 of 51; 92.2%). ALP elevation >1.5-fold of baseline or the high end of the reference range occurred in nine of 37 (24.3%) dogs, while ALT elevation above baseline and the high end of the reference range occurred in two of 36 (5.6%). Only six of 51 (11.8%) had clinical adverse events during treatment; five of six (83.3%) were mild reactions consisting of lethargy and gastrointestinal signs, while one dog had a possible cutaneous adverse drug reaction. Of those that experienced clinical adverse events, four of six (66.7%) did not have concurrent increased liver enzyme activity, while two of six (33.3%) had elevations in ALP alone. CONCLUSIONS AND CLINICAL RELEVANCE: Low-dose RFP (≤6 mg/kg/day) appears to be a relatively safe and effective single-agent systemic antibiotic in combination with topical antimicrobials for canine MDR MRS pyoderma.