LAUSR

Microbial resistance is an important problem in modern healthcare systems. In addition to drug resistance, the side effects of current antibiotic applications are also known issues. In this present study, binary combinations of amoxicillin with European Pharmacopoeia quality lavender (Lavandula angustifolia) and fennel (Foeniculum vulgare) essential oils were evaluated against human pathogenic microbial strains. The checkerboard method was used to quantify the efficacy of essential oils in combination with amoxicillin. As an initial result, remarkable in vitro antimicrobial activity was observed at relatively low amoxicillin concentrations using different oil combinations against Staphylococcus aureus ATCC 6538, Enterococcus faecalis ATCC 29212, Bacillus cereus ATCC 14579, and Escherichia coli NRRL B-3008, Salmonella typhi (Clinical isolate), respectively. Fractional inhibitory concentrations (FIC) were calculated and interpreted in terms of addition, synergy, antagonism, or indifferent, respectively. A synergistic interaction was shown for E. faecalis and E. coli with the combination F. vulgare essential oil and amoxicillin (FICI= 8.05 x 10-4). Both essential oils together, and in combination with amoxicillin showed a synergistic effect as well.