In vitro efficacy of a honey‐based gel against canine clinical isolates of Staphylococcus pseudintermedius and Malassezia pachydermatis

Abstract

Staphylococcus pseudintermedius and Malassezia pachydermatis are important agents in canine pyoderma and otitis. Determine the invitro efficacy of a honey-based gel (HBO) against meticillin-susceptible S.pseudintermedius (MSSP), meticillin-resistant S.pseudintermedius (MRSP) and M.pachydermatis, by minimum bactericidal concentration (MBC), minimum fungicidal concentration (MFC) and time-kill assay (TKA). Efficacy of the product's honey component (HO) also was evaluated. Sixty S.pseudintermedius and 10M.pachydermatis canine isolates were selected. All isolates were tested against serial dilutions of an HBO containing 40% HO (40%, 20%, 10%, 5% and 2.5% w/v) and HO alone (undiluted, 40%, 20%, 10%, 5% and 2.5% w/v). Microbroth assay followed by subculture was used to determine MBC and MFC. The same protocol was applied after product exposure to catalase. A well-diffusion assay for S.pseudintermedius was used to generate inhibition zones. A TKA for 10 isolates of S.pseudintermedius and 10 isolates of M.pachydermatis was performed. MBC was 20% w/v (5-20% w/v) for HBO and HO. HBO had lower MBC values when compared to HO (P=0.003). No statistical difference was observed between MSSP/MRSP isolates (HBO P=0.757, HO P=0.743). Only HO was affected by catalase (P=0.015). MFC for HBO was 10% w/v (5-10% w/v) and 40% w/v for HO (20-≥40% w/v). All isolates were killed after 4h of exposure. Staphylococcus pseudintermedius and M.pachydermatis are susceptible to the HBO and these results can be used for future clinical trials.