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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Microbiol. | doi: 10.3389/fmicb.2019.02607

Combined action of piperitenone epoxide and antibiotics against clinical isolates of Staphylococcus aureus and Escherichia coli.

  • 1Laboratory of Microbiology, Biotechnology and Hygiene, Department of Rural Development, Democritus University of Thrace, Greece
  • 2Laboratory of Chemistry and Biochemistry, Department of Rural Development, Faculty of Agriculture and Forestry Sciences, Democritus University of Thrace, Greece
  • 3Technological Educational Institute of Epirus, Faculty of Agricultural Technology, Food Technology and Nutrition, Greece
  • 4Laboratory of Physiology, Department of Medicine, Democritus University of Thrace, Greece
  • 5Laboratory of Microbiology, Department of Medicine, Democritus University of Thrace, Greece
  • 6Department of Internal Medicine, Lausanne University Hospital (CHUV), Switzerland

The aim of this study was to determine the antimicrobial efficiency of piperitenone epoxide (PEO) - a principal component of various aromatic plants' essential oil - in combination with various antibiotics against twenty eight strains of Staphylococcus aureus and ten strains of Escherichia coli isolated from clinical samples. Mentha spicata’s essential oil, initially collected by hydrodistillation, was then subjected to flush column chromatography affording PEO of high purity. Minimum Inhibitory Concentrations (MIC) of PEO alone and in combination with various concentrations of synthesized antibiotics was assessed by using the micro dilution method. The combined action was estimated calculating the Fractional Inhibitory Concentration Index (FICI) from checkerboard assays.
Our results showed that the average MIC (mg/L) of PEO alone against E. coli was 512 ± 364.7 μg/mL which was significantly higher than 172.8 ± 180.7 μg/mL observed for S. aureus. From checkerboard assays, FIC values below the 0.5 index, indicating synergy, were observed for 59% of the synthesized drugs tested. Twelve percent of FIC index values were between 0.5 and 1 indicating additive effects, while 21% were indifferent. According to our results, PEO could be a promising antimicrobial compound when combined with specific antibiotics and deserves further study.

Keywords: Piperitenone epoxide, antibiotic, E. coli - Escherichia coli, S. aureus, MIC - Minimal inhibition concentration, FIC activity, FICI values

Received: 28 Feb 2019; Accepted: 28 Oct 2019.

Copyright: © 2019 Alexopoulos, Kimbaris, Plessas, Mantzourani, Voidarou, Pagonopoulou, Tsigalou, Fournomiti, Bontsidis, Stavropoulou and Bezirtzoglou. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Athanasios Alexopoulos, Laboratory of Microbiology, Biotechnology and Hygiene, Department of Rural Development, Democritus University of Thrace, Orestiada, Greece, alexopo@agro.duth.gr