Cannabis sativa L. essential oil: chemical characterisation and antimicrobial activity against methicillin-resistant Staphylococcus pseudintermedius

Cannabis sativa L. essential oil has attracted the interest of the scientific community thanks to its numerous biological activities. Several studies have evaluated EOs as alternative therapeutic approaches to limit the use of antibiotics; the present study aimed to evaluate the in vitro inhibitory and bactericidal activity of the essential oils obtained from the leaves and inflorescences of two hemp genotypes against twenty-one multidrug-resistant, methicillin-resistant Staphylococcus pseudintermedius strains isolated from canine clinical samples. Both EOs were mainly represented by sesquiterpene hydrocarbons, with a prevalence of β-caryophyllene and α-humulene. However, different relative amounts of phytocannabinoids were also detected. Microbiological results evidenced better outcomes for the EO characterised by the highest content of phytocannabinoids, which in turn showed no differences among the tested strains. Nevertheless, both the EOs showed better inhibitory and bactericidal activities than their main constituent, β-caryophyllene, tested individually, highlighting the presence of synergistic effects among the EO compounds.