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Changes in antibiotic susceptibility in staphylococci habituated to sub-lethal concentrations of tea tree oil (Melaleuca alternifolia)

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

McMahon, M. A. S., Tunney, M. M., Moore, J. E., Blair, I. S., Gilpin, D. F. and McDowell, D. A. (2008) Changes in antibiotic susceptibility in staphylococci habituated to sub-lethal concentrations of tea tree oil (Melaleuca alternifolia). LETTERS IN APPLIED MICROBIOLOGY, 47 (4). pp. 263-268. [Journal article]

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DOI: 10.1111/j.1472-765X.2008.02420.x

Abstract

Aims: To investigate the effect of sub-lethal challenge with tea tree oil (TTO) on the antibiotic resistance profiles of staphylococci. Methods and Results: Isolates of methicillin-resistant/-sensitive Staphylococcus aureus (MRSA and MSSA) and coagulase-negative staphylococci (CoNS) were habituated to sub-lethal concentrations of TTO (72 h). Following habituation, the minimum inhibitory concentrations (MIC) of antibiotics and TTO were determined. Habituated MRSA/MSSA cultures had higher (P < 0.05) MIC values than control cultures for the examined antibiotics. Habituated MRSA/MSSA cultures also displayed decreased susceptibility to TTO. Although the MIC of habituated MRSA/MSSA for the examined antibiotics reverted to control values after subsequent culture in the absence of TTO, the increased MIC against TTO were maintained. When compared with control cultures, habituated CoNS cultures had higher (P < 0.05) MIC values against three-fifths of the antibiotics examined; no changes in TTO MIC were observed. Conclusions: TTO habituation `stress-hardens' MRSA and MSSA, evidenced by transient decreased antibiotic susceptibility and stable decreased TTO susceptibility. Although TTO habituation did not decrease susceptibility of CoNS to TTO, such cultures showed transient decreased antibiotic susceptibility. Significance and Impact of the Study: Application of TTO at sub-lethal concentrations may reduce the efficacy of topical antibiotics used with TTO in combination therapies.

Item Type:Journal article
Keywords:CoNS; MRSA; MSSA; staphylococci; tea tree oil
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Health Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Infection and Immunity/Microbiology
ID Code:6110
Deposited By:Dr Ann McMahon
Deposited On:13 Jan 2010 11:38
Last Modified:01 Mar 2012 15:00

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