Evaluation of the in vitro antibacterial activity of some essential oils and their blends against Staphylococcus spp. isolated from episodes of sheep mastitis

Abstract

Staphylococcus aureus and coagulase-negative staphylococci are among the major causes of mastitis in sheep. The main goal of this research was to determine the in vitro antibacterial activity of several essential oils (EOs, n 30), then five of them were chosen and tested alone and in blends against staphylococci isolates. Five bacteria were isolated from episodes of ovine mastitis (two S. aureus and three S. xylosus). Biochemical and molecular methods were employed to identify the isolates and disk diffusion method was performed to determine their antimicrobial-resistance profile. The relative percentage of the main constituents in the tested essential oils and their blends was detected by GC-EIMS analysis. Antibacterial and bactericidal effectiveness of essential oils and blends were evaluated through minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). All of them showed sensitivity to the used antimicrobials. The EOs with the highest antibacterial activity were those belonging to the Lamiaceae family characterized by high concentrations of thymol, carvacrol and its precursor p-cymene, together with cinnamon EO, rich in cinnamaldehyde. In terms of both MIC and MBC values, the blend composed by Thymus capitatus EO 40%, Cinnamomum zeylanicum EO 20%, Thymus serpyllum EO 20% and Satureja montana EO 20% was found to be the most effective against all the isolates. Some essential oils appear to represent, at least in vitro, a valid tool against ovine mastitis pathogens. Some blends showed a remarkable effectiveness than the single oils, highlighting a synergistic effect in relation to the phytocomplex.

Chemical Composition, Antimicrobial Activity, and Withdrawal Period of Essential Oil-Based Pharmaceutical Formulation in Bovine Mastitis Treatment

“…Some blends of EOs showed more remarkable effectiveness than the single oils, highlighting a synergistic effect in relation to the phytocomplex [ 23 ]. Different types of components in the combination may affect multiple biochemical processes in the bacteria, improve the bioavailability of the combined agents, overpower the drug resistance mechanisms of bacteria, and neutralize the adverse effects of the components [ 55 ].…”

“…Thymus vulgaris L., Thymus serpyllum L., Satureja montana L., and Origanum vulgare L. belong to the Lamiaceae family, known for its diverse biological and pharmacological properties [ 23 ]. EOs from the genus Thymus exhibit different biological properties such as antioxidant, antibacterial, antifungal, antiviral, antiparasitic, cytotoxic, and spasmolytic [ 24 , 25 ].…”

The effects of Thymus capitatus essential oil topical application on milk quality: a systems biology approach

“…f., Thymus capitatus (L.) Hoffmanns. & Link, Thymus marinosci Ten., Spanish oregano or Thymbra capitata (L.) Thymus capitatus has been investigated for its essential oil's antioxidant, antimicrobial, and antiviral properties [18][19][20][21][22][23][24][25][26] and its anti-in ammatory effects. It has been reported that it can inhibit the expression of in ammatory cytokines, iNOS, and COX-2, as well as suppress the production of neutrophil elastase and the synthesis of PGE2 [27][28][29] .…”