Antimicrobial activity of formulated clove essential oil spray against biofilm-forming Malassezia pachydermatis and Staphylococcus pseudintermedius clinical isolates

Yeasts and bacteria that cause infectious skin diseases in animals are becoming increasingly resistant to antimicrobial drugs, especially biofilm-forming microbial strains. Therefore, there is extensive interest in new effective antimicrobial substances. Clove essential oil has broad-spectrum antimicrobial activity and can be developed into various dosage forms. This study investigated the antimicrobial effects of a lipid-based spray containing 5% w/w clove essential oil against biofilm-forming Malassezia pachydermatis and Staphylococcus pseudintermedius clinical isolates by time-kill test. In addition, the physical stability and antimicrobial activity of the spray was assessed under accelerated storage conditions. The time kill tests revealed that the prepared formulation decreased the number of viable yeast and bacteria by more than 99.9999% (6-log reduction) within 15 mins. After storage at 40(0)C and 75% RH for 4 months, the spray showed a slight increase in acidity and a slight darkening in colour. The antimicrobial and bactericidal activity was unaffected but the anti-yeast activity diminished slightly in the 3rd and 4th months under accelerated storage conditions. These results demonstrate the efficacy of clove essential oil lipid-based spray against biofilm-forming M. pachydermatis and S. pseudintermedius.