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

Abstract

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 400C 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 3 rd and 4 th 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.