Essential oils : antimicrobial effect against hospital pathogens and toxicity to human skin fibroblasts

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Essential oils : antimicrobial effect against hospital pathogens and toxicity to human skin fibroblasts


Author: Lai, Kim-ping
Title: Essential oils : antimicrobial effect against hospital pathogens and toxicity to human skin fibroblasts
Degree: M.Sc.
Year: 2007
Subject: Hong Kong Polytechnic University -- Dissertations.
Fibroblasts -- Treatment.
Essences and essential oils.
Tea tree oil.
Department: Dept. of Health Technology and Informatics
Pages: viii, 48 leaves : col. ill. ; 30 cm.
Language: English
InnoPac Record:
Abstract: Essential oils, including lavender, myrrh, patchouli and tea tree oils, are commonly used in the past and present. They are shown to have significant antibacterial activities and were applied in medical treatment and daily products. In order to explore the applicability of essential oils for treatment of wound infections, antimicrobial effects of essential oils against common pathogens responsible for wound infections were studied. In addition, toxic effects of essential oils on human skin fibroblasts were assessed. Minimum inhibitory concentrations (MICs) of essential oils against clinical strains of Staphylococcus aureus (n=11), Methicillin-resistant Staphylococcus aureus (n=16), Escherichia coli (n=23), Klebsiella pneumoniae (n=27), Pseudomonas aeruginosa (n=29), Enterococcus (n=16) and Candida albicans (n=11) were performed by using agar dilution method. Time-kill assays were performed on control bacterial strains with high MIC values against essential oils, antibacterial effect was demonstrated by determination of growth rate change. Toxicities to human skin fibroblasts (SCRC 1041) were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetra2olium bromide (MTT) assay. Results of the MIC determination showed that lavender and tea tree oils were more effective against Gram-positive bacteria and Candida albicans than Gram-negative bacteria. Patchouli was effective against Gram-positive bacteria but less effective against Gram-negative bacteria and Candida albicans. Myrrh showed the least antimicrobial effect against all tested microorganisms. Results of the time-kill assays showed that myrrh exerted antibacterial effect against tested micro-organisms. Patchouli can inhibited the growth of Gram-negative organisms and four tested essential oils can reduced the growth of Ps. aeruginosa For the results of MTT assay found that these four essential oils cross-reacted with the MTT substrate. Therefore, results of the MTT assay could not be interpreted. It is suggested that trypan blue exclusion method can be used as an alternative means for assessment of toxicity of essential oils to human skin fibroblasts. In summary, although the study on toxic effects of essential oils yielded no conclusive results, valuable information on antimicrobial activities of essential oils against various hospital wound pathogens was obtained. In order to apply essential oils as therapeutic agents, more extensive clinical studies are required to verify the tolerability of essential oils on human tissues.

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