Antimicrobial effect of the essential oil from Rosmarinus officinalis L. against Staphylococcus pseudintermedius isolated from dogs

Abstract

This study evaluated the inhibitory effect of Rosmarinus officinalis L. (rosemary) essential oil (ROEO) against 18 isolates of Staphylococcus pseudintermedius isolated from dogs affected by pyoderma in Brazil, by determining the minimum inhibitory concentrations (MIC) and the effects on the bacterial cell viability over 16 h. MIC values of ROEO against the isolates were 2.5 µL/mL (3/18), 5 µL/mL (12/18) or 10 µL/mL (3/18). At all concentrations tested  (¼, ½, 1x, 2x and 4x MIC) the ROEO inhibited  bacterial cell viability after 30 min of exposure, and no recovery in viable cell counts was noted in the later intervals. The ROEO at ½, 1x, 2x and 4x MIC established its bactericidal effect within a maximum exposure time of 16 h. These findings reveal an interesting anti-S. pseudintermedius effect of ROEO, with a rapid and steady kill rate.