Abstract: Methicillin-resistant S. aureus is a major cause of community and hospital acquired infections. There is an urgent need to develop anti-MRSA agents with novel mechanisms of action. Eucalyptus is a tall and evergreen tree, which is cultivated in many countries. Essential oil of Eucalyptus and their major constituents possess toxicity against a wide range of microbes including bacteria and fungi. In the present study, antibacterial activity of Eucalyptus alcoholic and aquatic extracts were investigated against a battery of clinically important MRSA strains. The alcoholic extract of Eucalyptus leaves was obtained by 95% ethanol and aquatic extract by boiling from the fresh leaves. Different concentrations of extracts were prepared and used for the antibacterial assay by agar well diffusion method. Bacterial DNA extracted by lysostaphin and boiling method was used to detect mecA gene from standard and clinical strains using a PCR amplification assay. Result of this study show that alcoholic and aquatic extract of Eucalyptus have antibacterial effects. In mecA negative Staphylococcus aureus the maximum zone of alcoholic extract was 18 mm at 30 μL volume, whereas in mecA positive Staphylococcus aureus the maximum zone of alcoholic extract was 14 mm at 30 μL volume. Among the various components of Eucalyptus oil, 1,8-cineole is the most important and is largely responsible for a variety of its antibacterial properties. According to the results, alcoholic extract of Eucalyptus has higher antibacterial effect than aquatic extract. Due to various chemical components of Eucalyptus more attention must be taken for the clinical application of this plant.
Fatemeh Mohsen Nezhad, Habib Zeigham, Ali Mota, Morteza Sattari and Abbas Yadegar, 2009. Antibacterial Activity of Eucalyptus Extracts on Methicillin Resistance Staphylococcus aureus. Research Journal of Biological Sciences, 4: 905-908.