Effect of Manuka essential oil on Staphylococcus pseudintermedius

Abstract

Staphylococcus pseudintermedius is a primary pathogen of bacterial skin infections in dogs. Recently, the emergence of methicillin-resistant S. pseudintermedius (MRSP) has become a challenge because it shows resistance toward various kinds of antibiotics. Thus, there is growing interest in novel antimicrobial compounds and Manuka is one of these. The aim of this study was to confirm the antimicrobial and biofilm formation inhibition activities of Manuka essential oil against clinically isolated S. pseudintermedius, including MRSP. Fifty S. pseudintermedius were isolated from clinical cases of canine pyoderma and otitis externa and show a high MRSP rate (78%). To confirm the antimicrobial activity of Manuka essential oil, the minimum inhibitory concentrations (MICs) of Manuka essential oil for S.pseudintermedius isolates were determined using the agar dilution method and the results were compared with cephalexin. The MICs of Manuka essential oil and cephalexin against 50 S. pseudintermedius isolates ranged from 2-6 to 2- 9 (v/v) and 0.125 to 128 mg/ml, respectively. Only 41 isolates (82%) were susceptible to cephalexin

however, Manuka essential oil showed antimicrobial activity against all clinically islolated S. pseudintermedius, including MRSP (2-7 to 2-9 v/v). Biofilm formation was assessed by colorimetric assay with crystal violet staining. Statistically significant (p<0.05) inhibition of biofilm formation was found in S. pseudintermedius exposed to 0.01%, 0.1%, and 1% (v/v) Manuka essential oil, dose-dependently. These results showed that Manuka essential oil has antimicrobial and antibiofilm formation activity on S. pseudintermedius and can be a potential treatment option for controlling S. pseudintermedius infections in dogs.