• Yordanka Mihaylova
  • Neli Ermenlieva Medical University Varna. Faculty of Medicine, Department of Microbiology and Virusology, Varna, Bulgaria
  • Sylvia Stamova Medical University Varna, Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Varna, Bulgaria
  • Silviya Mihaylova Medical University Varna, Medical College, Varna, Bulgaria
  • Emilia Georgieva edical University Varna, Medical College, Varna, Bulgaria
  • Antoaneta Tsvetkova Medical University Varna, Medical College, Varna, Bulgaria
  • Kalina Georgieva Medical University Varna, Medical College, Varna, Bulgaria



antimicrobial activity, Lamiaceae, essential oils, MIC, MBC


The aim of this study is to evaluate the potential antimicrobial activity of four commercial essential oils: Thymus vulgaris and Origanum vulgare (two for external use and two for internal one). The antimicrobial activity of the tested essential oils was determined by using the serial two-fold dilutions method. The following bacterial and yeast strains were purchased and used in the study: E. coli, S. aureus, and C. albicans. The minimal inhibitory concentration (MIC) of Thyme oil (external use) against E. coli, and C. albicans was 2 µg/ml and 4 µg/ml, respectively. The observed minimum bactericidal concentration (MBC) for Thyme oil (external use) against S. aureus was 8 µg/ml. The Thyme oil for internal use demonstrated higher antimicrobial activity than the topical form. The evaluated MBC against S. aureus was 4 µg/ml, and for E.coli, and C. albicans, it was even lower than 1 µg/ml.  While determining the MBC of Oregano oil (external) against S. aureus, E. coli, and C. albicans, antimicrobial activity is reported as : 16 µg/ml against S. aureus, 4 µg/ml for E.coli and 32 µg/ml against C. albicans. Also, the observed antimicrobial activity of Oregano oil for internal use is higher than external form – 2 µg/ml against S. aureus and lower than 1 µg/ml for the other pathogens. The results of MIC and MBC determination of Thyme and Oregano oils showed that E. coli, S. aureus and C. albicans demonstrate high sensitivity and  can be used in therapeutic practice, and some of them probably in combination with other antimicrobial agents.


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How to Cite

Mihaylova, Y. ., Ermenlieva, N. ., Stamova, S., Mihaylova, S. ., Georgieva, E. ., Tsvetkova, A. ., & Georgieva, K. . (2022). IN VITRO STUDY OF ANTIMICROBIAL ACTIVITY OF COMMERCIAL ESSENTIAL OILS OF THE LAMIACEAE FAMILY AGAINST STAPHYLOCOCCUS AUREUS ATCC 29213, ESCHERICHIA COLI ATCC 25922 AND CANDIDA ALBICANS ATCC 10231. Proceedings of CBU in Natural Sciences and ICT, 3, 8-11.
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