Interprofessional Journal of Health Sciences. Vol.15 No.2 , July - December 2017.

In vitro Investigation of Antimicrobial Activity of Essential Oil against Methicillin Resistant STAPHYLOCOCCUS AUREUS (MRSA)

Srirachawadi Sroiphetcharat , Patamaporn Sukplang, and Acharawan Thongmee

Abstract

Staphylococcus aureus is one of the major causes of both community and hospital acquired infections. Methicillin-resistant S. aureus (MRSA) is one of the S. aureus strains that resists a variety of antibiotics, especially methicillin and penicillin groups.   Therefore, very few antibiotics are effective in treating MRSA infections.   Many compounds were developed for the treatment of MRSA infections. Some essential oils are good candidates due to their antimicrobial potentials. In this study, eleven essential oils, i.e., clove, geranium rose, kaffir lime, lavender, lemongrass, mandarin orange, patchouli, plai, rosemary, Siamese rosewood, and vetiver were evaluated.   These oils were determined for antimicrobial activities against MRSA and MSSA by the agar disk diffusion method.  Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were also determined.   In addition, the effectiveness of the potent essential oils were analyzed using the time-kill assay.  The agar disk diffusion test showed that lemongrass oil possessed the highest antibacterial activity against MRSA and MSSA with inhibition zones of 29.4 ± 3.3 mm and 28.3 ± 4.7 mm, respectively.  Clove oil and geranium oil also showed antibacterial activity against MRSA and MSSA with inhibition zones of 15.3 ± 2.1 mm and 15.5 ± 1.7 mm for clove oil and 13.2 ± 2.3 mm. and 12.1 ± 1.3 mm for geranium oil, respectively.   Therefore, lemongrass oil, clove oil and geranium oil were selected for further determination of MIC and MBC. The results showed that the MIC and MBC against MRSA were 0.3906 % v/v and 0.3906 % v/v for clove oil, 0.3906 % v/v and 1.5625 % v/v for geranium oil and 0.7813 % v/v and 3.125 % v/v for lemongrass oil.  Kinetics of kill studies showed that lemongrass oil at its 1MIC had more killing effect than clove and geranium oil at their 1MIC. Lemongrass oil killed MRSA and MSSA at least 3 logs in 1 minute whereas geranium oil took more than 5 minutes to achieve the same kill.

Keywords: Essential oils, Antimicrobial activity, Methicillin-resistant S. aureus

Download Full Paper.