Bactericidal Activity of the Essential Oil of Thymus Ciliatus on Staphylococcus Aureus
The essential oil extracted from the aerial parts of Thymus ciliatus, harvested in the region of Tawra (North-East Algeria), gave an excellent yield of 2.5%. Its analysis by GC / MS allowed identification of twenty-four elements, mainly phenols and terpens. The main components are: thymol (67.78%), p-cymen (12.25%), pseudo-limonen (5.10%), and γ -terpinen (4.42%). The main of this study is to evaluate the antibacterial activity of this essential oil on a bacterial population consisted of forty-four strains of Staphylococcus aureus resistant to methicillin (MRSA), isolated from different food products. For that, we used the agar diffusion method as recommended by the European Committee on Antimicrobial Susceptibility Testing [CASFM- EUCAST; 2014- V2]. The calculation of minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined by the medium agar incorporation method as recommended by [CASFM- EUCAST; 2014- V2]. MRSA strains tested, showed a high sensitivity in respect of the essential oil with inhibition diameters ranging from 20mm to 50mm and relatively low MICs values ranging from 180μg/ml and 720μg/ml, and CMBs values ranging from 180μg/ml and 2160μg /ml. The essential oil of T. ciliatus showed a bactericidal effect on all isolated MRSA with a very important report CMB / CMI = 1 .The bactericidal power of this oil suggests its use in foods as a substitute for conventional chemical preservatives.
Keywords - Essential oil - Thymus ciliatus -Antibacterial activity - CMI – CMB - MRSA.