Rifampicin treatment of canine pyoderma due to multidrug-resistant meticillin-resistant staphylococci: a retrospective study of 32 cases Michela De Lucia*, Mar Bardagi†, Elisabetta Fabbri‡, Diana Ferreira§, Lluis Ferrer¶, Fabia Scarampella**, Giordana Zanna†† and Alessandra Fondati‡‡ *Clinica Veterinaria Privata San Marco, Via Sorio 114/C, 35141 Padova, Italy †Department de Medicina i Cirurgia Animals, Universitat Aut onoma de Barcelona, 08193 Bellaterra, Barcelona, Spain ‡U.O. Qualit a, Ricerca Organizzativa e Innovazione, AUSL della Romagna, Via De Gasperi 8, 48121 Ravenna, Italy §Centre for Small Animal Studies, Animal Health Trust, Newmarket, Suffolk, CB8 7UU, UK ¶Department of Clinical Sciences, Tufts Cummings School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA 01536, USA **Studio Dermatologico Veterinario, Via G. Sismondi 62, 20133 Milan, Italy ††Istituto Veterinario di Novara, SP 9 28060, Granozzo con Monticello (NO), Italy ‡‡Veterinaria Cetego Via M.C. Cetego 20 and Ambulatorio Veterinario Trastevere Viale Glorioso 23, 00153 Roma, Italy Correspondence: Michela De Lucia, Clinica Veterinaria San Marco, Via Sorio 114/C, 35141 Padova, Italy. E-mail: michela_delucia@sanmarcovet.it Background – Rifampicin has received increased interest in veterinary dermatology because of its activity against multidrug-resistant meticillin-resistant staphylococci (MRS). There is limited knowledge about the effi- cacy and safety of rifampicin in dogs. Hypothesis/Objective – To provide information on response to treatment and adverse effects in dogs treated with rifampicin for multidrug-resistant MRS pyoderma. Animals – Thirty two dogs treated with rifampicin for rifampicin-susceptible multidrug-resistant MRS pyoderma. Methods – Retrospective review of medical records, including alanine aminotransferase (ALT) and alkaline phos- phatase (ALP) serum activity levels and total bilirubin concentrations, obtained before and throughout the treat- ment, was performed. Results – Oral rifampicin as sole systemic antimicrobial therapy (median dose 5 mg/kg twice daily) was effective in 71.88% of cases. Topical antimicrobials were used in most cases. Median duration of rifampicin treatment was five weeks for superficial pyoderma and four weeks for deep pyoderma. Gastrointestinal signs were reported in 15% of treated dogs. Statistically significant increases of ALT (P = 0.045) and ALP (P = 0.0002) val- ues after 3–4 weeks of treatment was observed. The median increase was equal to 0.3 and 91.5 the upper limit of the reference ranges for ALT and ALP, respectively. Conclusions/Clinical importance – Oral rifampicin combined with topical antimicrobials can be considered an effective therapeutic option for canine superficial and deep pyoderma caused by rifampicin-susceptible mul- tidrug-resistant MRS. Liver enzyme induction might be the most important cause of ALT and ALP increase asso- ciated with rifampicin therapy in dogs. Introduction Canine pyoderma caused by meticillin-resistant staphylo- cocci (MRS) represents a therapeutic challenge as MRS are often multidrug-resistant and susceptible only to sys- temic antimicrobials, such as amikacin, chloramphenicol and rifampicin, that are potentially associated with moder- ate to severe adverse effects. 1–3 Although topical antimi- crobial agents might be effective and should be used preferentially to treat superficial cutaneous infections in dogs, systemic antimicrobials still represent the mainstay of treatment for generalized deep pyoderma and those superficial pyodermas not responsive to topical therapy or that cannot be treated topically due to poor compli- ance. 4,5 Rifampicin is the International Nonproprietary Name used for the drug in Europe, which is synonymous with rifampin, the name approved by the United States Phar- macopeia. It is an older drug that has recently seen increased interest in veterinary dermatology because of its activity against multidrug-resistant MRS. 6 Rifampicin exerts its bactericidal activity by forming stable com- plexes with the b subunit of DNA-dependent RNA poly- merase enzymes of microorganisms, thus inhibiting bacterial RNA synthesis. 7 Due to its excellent penetration in phagocytic membranes, rifampicin concentrates intra- cellularly in neutrophils and macrophages and kills ingested bacteria, thus being especially valuable for treat- ing chronic granulomatous lesions. 7,8 Owing to the rapid emergence of staphylococcal resistance which may occur after a single or double mutation in the RNA Accepted 10 October 2016 Sources of Funding: This study was self-funded. Conflict of Interest: No conflicts of interest have been declared. © 2016 ESVD and ACVD, Veterinary Dermatology 1 Vet Dermatol 2016 DOI: 10.1111/vde.12404