Bacterial infections are in less-developed countries traditionally treated by remedies prepared from medicinal plants. Embelia schimperi (Vatke) is a plant used as a taenicide or disinfectant in Ethiopia, very often taken mixed with another plant species. In the present study, we examined two extracts prepared from seeds and twigs with leaves of E. schimperi and its main present secondary metabolite embelin for their antibacterial combinatory effect with oxacillin and tetracycline against sensitive and resistant Staphylococcus aureus strains. Minimum inhibitory concentrations were determined through the broth microdilution method, whereas the combinatory effect was evaluated through fractional inhibitory concentration sum (ΣFIC) indices. Results show many positive interactions and synergy occurring in embelin and oxacillin combinations against 4 out of 9 strains (ΣFIC 0.203-0.477) and for embelin and tetracycline combination against 3 out of 9 strains (ΣFIC 0.400-0.496). Moreover, the resistance to oxacillin has been overcome in 2 strains and to tetracycline in 3 strains. According to our knowledge, this is the first study showing antimicrobial combinatory effect of E. schimperi as well as of embelin. These findings can be used for the further research targeted on the development of new antistaphylococcal agents.

Department of Biology College of Natural Sciences 445 Debre Berhan University Debre Berhan Ethiopia

Department of Crop Sciences and Agroforestry Faculty of Tropical AgriSciences Czech University of Life Sciences Prague Kamycka 129 Suchdol 165 21 Prague 6 Czech Republic

Department of Crop Sciences and Agroforestry Faculty of Tropical AgriSciences Czech University of Life Sciences Prague Kamycka 129 Suchdol 165 21 Prague 6 Czech Republic ; Laboratory for Tropical and Subtropical Agriculture and Ethnobotany Department of Plant Production Faculty of Bio Science Engineering Ghent University Coupure links 653 9000 Ghent Belgium

Department of Microbiology Nutrition and Dietetics Faculty of Agrobiology Food and Natural Resources Czech University of Life Sciences Prague Kamycka 129 Suchdol 165 21 Prague 6 Czech Republic

Laboratory for Tropical and Subtropical Agriculture and Ethnobotany Department of Plant Production Faculty of Bio Science Engineering Ghent University Coupure links 653 9000 Ghent Belgium ; Department of Plant Biology and Biodiversity Management College of Natural Sciences Addis Ababa University P O Box 3434 Addis Ababa Ethiopia

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