In vitro activity of essential oils on microorganisms isolated from vaginal infections

The antibacterial and antifungal activity of ten essential oils was tested against a range of vaginal bacterial and fungal strains isolated from existing vaginal infections including Atopobium vaginae, Gardnerella vaginalis, Bacteroides vulgatus, Streptococcus agalactiae, H₂O₂-producing lactobacilli and non H₂O₂-producing lactobacilli, Candida albicans, Candida glabrata, Candida parapsilosis and Candida tropicalis.

Investigation of the in vitro susceptibility of the essential oils against bacteria revealed that lemongrass, tea tree and lavender exhibited the lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) at 1–2.5 μl/ml, thus being the most potent essential oils against the tested bacteria. Interestingly, the MIC and MBC values of palmarosa, neroli, manuka, rose-scented geranium, rosemary, common thyme and clary sage were at ⩾7.5 μl/ml for protective H₂O₂-lactobacilli but lower for pathogentic bacteria. The MIC and minimal fungicidal concentration (MFC) for lemongrass, palmarosa, lavender and rose scented geranium were at 1–2.5 μl/ml. All other essential oils were less potent.

Overall, lemongrass, palmarosa, lavender and rose scented geranium were the most potent oils in the inhibition of pathogenic bacteria and fungi. However, further investigations in the form of clinical studies are necessary to ascertain the therapeutic use of these essential oils in the combat of vaginal infections.