Essential oils as potential anti-staphylococcal agents

Abstract

Antibiotic therapy of staphylococcal mastitis is characterized by significantly lower cure rates compared to infections caused by other microorganisms. Thus, it is necessary to search for new, alternative, non-antibiotic agents that are effective in the eradication of these bacteria. The aim of our research was to investigate the antimicrobial, especially anti-staphylococcal potential of a large collection (n=36) of essential oils (EOs). Investigation of the antimicrobial activity of tested oils was determined by using a serial, twofold dilution method in 96-wells microtiter plates under conditions recommended by the Clinical and Laboratory Standards Institute (CLSI). The preliminary analysis revealed that six oils, namely: Manuka, Thyme, Geranium, Cedar, Cinnamon (from bark) and Patchouli exhibited the highest activity against reference strains of bacteria. Significant anti-staphylococcal potential of these oils has been also confirmed for a group of 18 Staphylococcus aureus, 8 Staphylococcus epidermidis and 5 Staphylococcus xylosus strains isolated from cases of bovine mastitis. Especially high activity was observed for Cedar, Patchouli, Thyme and Manuka oils. The MIC (Minimal Inhibitory Concentration) values for Patchouli oil were in the concentrations range of 0.01 to 0.313% (v/v). The three other oils inhibited the growth of staphylococci isolated from mastitis in the concentrations range of 0.01 to 0.625% (v/v). Oils isolated from Cinnamomum cassia and Pelargonium graveolens revealed a bit lower, but still satisfactory activity (MIC values in the concentrations range of 0.02 to 1.25% (v/v) and from 0.078 to 1.25% (v/v), respectively). In many cases a slightly higher concentration of oils was required to obtain the bactericidal effect in comparison to growth inhibition. The time – kill kinetic assay revealed that the bactericidal effect was achieved after two hours incubation of the reference strain S. aureus PCM 2051 cells with Thyme oil at concentration equal to 2xMIC (1.25% (v/v)) or MIC (0.625% (v/v)). A slightly lower activity was observed in the case of Cinnamon oil, the bactericidal effect was achieved after 8 hours of incubation. The results of our research clearly indicate that some essential oils exhibit a promising antimicrobial activity and can be considered as alternative antistaphylococcal agents.

In Vitro Efficacy of Essential Oils from Melaleuca Alternifolia and Rosmarinus Officinalis, Manuka Honey-based Gel, and Propolis as Antibacterial Agents Against Canine Staphylococcus Pseudintermedius Strains

“…Essential oils and honeybee products are widely used in veterinary medicine as arthropod repellents, for topical administration (e.g., shampoo), and as antimicrobials and antifungals [41][42][43][44].…”

Antimicrobial Activity of Some Essential Oils against Methicillin-Susceptible and Methicillin-Resistant Staphylococcus pseudintermedius-Associated Pyoderma in Dogs

“…In recent years, several studies were carried out both in vivo and in vitro on the efficacy of some EOs against the etiological agents of pyoderma in dogs [ 7 , 8 , 9 ]. Many EOs can be used in these skin disorders; however, thanks to their bioactive chemical compounds, some of them are effective tools especially against Gram-positive bacteria [ 10 ].…”

“…With regard to the antibacterial activity of manuka essential oil, not many data are available; however, some recent researches reported good activity against Staphylococcus spp. and in general against Gram-positive bacteria, thanks to the presence of some compounds such as leptospermone and isoleptospermone [ 8 , 12 ]. In particular, one study analyzed the efficacy of manuka EO against S. pseudintermedius isolated from canine pyoderma and otitis samples, highlighting its excellent activity against all these bacterial isolates [ 13 ].…”

The Anti-Staphylococcal Potential of Ethanolic Polish Propolis Extracts

“…Due to the growing frequency of isolation of staphylococcal strains resistant to currently used antibiotics, their high virulence potential and common presence in environmental, there is an urgent need to search for new agents as well as therapy systems effective against these bacteria. The most promising alternative, non-antibiotic agents that exhibit anti-staphylococcal (including MRSA isolates) activity include: bacteriocins [4,5], bacteriophages [6,7], peptidoglycan hydrolases [8] compounds of plant origin - plant extracts, essential oils and their components [9,10,11,12] and silver nanoparticles [9,13]. Selection of resistant strains can be limited by combined therapy—simultaneous use of at least two antibiotics/agents that affect different molecular targets [14,15].…”