Essential oils showing in vitro anti MRSA and synergistic activity with penicillin group of antibiotics

ABSTRACT

This study was planned in order to investigate effective essential oils to inhibit in-vitro growth of Methicillin resistant Staphylococcus aureus [MRSA]. In this study using disc diffusion method anti MRSA activity of ten diverse essential oils extracted from traditional plants namely Thymus vulgaris L, Mentha pulegium, Ocimum sanctum, Mentha piperita, Cymbopogon citratus, Rosmarinus officinalis L., Cortex cinnamom, Citrus nobilis x Citrus deliciosa, Origanum vulgare and Mentha sp. was examined. All the essential oils inhibited growth of S. aureus to different extent, by exhibiting moderate to elevated zones of inhibitions. Essential oils of cinnamon [Cortex cinnamomi] and thyme [Thymus vulgaris L] were observed to be the most powerful against MRSA strains used in this study. At lowest concentration of 25 micro l/ml essential oils comprehensible zone of inhibition was found 9+/-0.085mm and 8+/-0.051mm respectively, and at elevated concentrations there was a total decline in growth of MRSA and a very clear zone of inhibition was observed. A synergistic effect of essential oils in amalgamation with amoxicillin a Penicillin group of antibiotic was also examined. Interestingly a strong synergism was observed with oregano [Origanum vulgare] and pennyroyal mint [Mentha pulegium] essential oils, which were not so effective alone driven out to be important synergistic candidate. Our results demonstrated that essential oils of cinnamon and thyme can be used as potential antimicrobial agent against the Methicillin-resistant Staphylococcus aureus infections and Amoxicillin antibacterial activity can be enhanced using active constituents present in oregano and pennyroyal mint essential oils