In vitro miconazole susceptibility of meticillin-resistant Staphylococcus pseudintermedius and Staphylococcus aureus

Background The emergence and dissemination of meticillin-resistant staphylococci has created significant treatment challenges in veterinary medicine and increased interest in topical therapy for superficial infections. Concern has been expressed regarding the use of some topical antimicrobials in animals because of the potential for emergence of resistance, and additional options are required. Miconazole has limited antibacterial properties that include antistaphylococcal activity. Hypothesis/Objectives The objective of this study was to assess the in vitro susceptibility of Staphylococcus pseudintermedius and Staphylococcus aureus to miconazole. Methods In vitro susceptibility of 112 meticillin-resistant S. pseudintermedius (MRSP), 53 meticillin-resistant S. aureus (MRSA) and 37 meticillin-susceptible S. pseudintermedius (MSSP) to miconazole was assessed using agar dilution. Results The minimal inhibitory concentration (MIC) range, MIC50 and MIC90 for MRSP were 18, 2 and 4 mu g/mL, respectively. Corresponding results for MRSA were 18, 2 and 6 mu g/mL, and for MSSP 14, 2 and 2 mu g/mL. The MIC for MSSP was a significantly lower MIC than that for both MRSP (P = 0.006) and MRSA (P < 0.001), while the MIC for MRSP was significantly lower than that for MRSA (P = 0.001). Conclusions and clinical importance These in vitro data suggest that miconazole could be a useful therapeutic option for superficial infections caused by meticillin-susceptible and meticillin-resistant staphylococci, but proper clinical investigation is required.