Evaluation of in vitro antimicrobial effect of different essential oils

Abstract

Objective: In this study, it was aimed to investigate the antimicrobial effect of 16 different essential oils bycommercially sold, against different standard bacterialstrains and one clinical bacterial strain and one standardyeast strain.Methods: Essential oils used in the study weredetermined in parallel with the relevant literaturereview. Microbial strains were obtained from AmericanType Culture Collection (ATCC) and Sivas CumhuriyetUniversity Application and Research Hospital ClinicalMicrobiology Laboratory. Study inoculums weredetermined according to the McFarland 0.5 standard,and antimicrobial activity was investigated accordingto the standard disk diffusion method of the EuropeanCommittee on Antimicrobial Susceptibility Testing(EUCAST).Results: Essential oils and inhibition zone valuesthat have the highest effect against the standardstrains and the clinical isolate used in the researchare as follows: to Thymus vulgaris; Staphylococcusaureus ≥50 mm, Acinetobacter baumannii 43 mm,Escherichia coli 35 mm, Enterococcus feacalis 35 mm;Klebsiella pneumoniae 9 mm, Candida albicans ≥50 mm; to Melaleuca alternifolia; Staphylococcus aureus14 mm, Acinetobacter baumannii 19 mm, Escherichiacoli 20 mm, Enterococcus feacalis ≤10 mm, Klebsiellapneumoniae 13 mm, Candida albicans ≥50 mm; toMentha piperita; Staphylococcus aureus ≥50 mm,Acinetobacter baumannii 20 mm, Escherichia coli 18mm, Enterococcus feacalis 14 mm, Candida albicans≥ -50 mm, Klebsiella pneumoniae no inhibition zonewas observed. To Lavandula officinalis; Staphylococcusaureus 16 mm, Acinetobacter baumannii 10 mm,Escherichia coli 11 mm, Enterococcus feacalis 14 mm,Candida albicans 18 mm and Klebsiella pneumoniae noinhibition zone was observed.Conclusion: The essential oils, whose effects wereinvestigated against standard bacterial strains, a clinicalbacterial isolate, and yeast strain, it was observed thathigh antimicrobial activities at different levels. It wasobserved that thyme, tea tree, mint and lavenderessential oils among the essential oils studied hadstronger antimicrobial effect than other essential oils.As a result, we think that these essential oils, which wehave investigated, may contribute to the study of newantimicrobial substances, and antimicrobial drug due totheir high antimicrobial effect