Method: The minimum inhibitory concentration (MIC) of the essencial oil was determined by the broth microdilution assay according to the Clinical and Laboratory Standards Institute (CLSI). The effects of M. alternifolia were also tested against biofilms of C. albicans formed after 48h in the bottom of 96-well microtiter plates. For the in vivo study, thirty immunosuppressed mice were submitted to development of candidiasis on the tongue dorsum by C. albicans inoculations. After 24h, topical applications of the essential oil from M. alternifolia were performed on the tongue dorsum. In the control group, the mice received only applications of physiological solution. Samples of the oral cavity were collected for a count of colony-forming units per mL. The mice were killed for morphologic analysis of the tongue dorsum by optical and scanning electron microscopy. The results were analysed by Student t test (p<0.05).
Result: We observed that the MIC of the essencial oil from M. alternifolia was 0.195% and a mean reduction of 6.88 log was achieved for biofilms of C. albicans. In the in vivo study, the treatment with M. alternifolia achieved reduction of 6.49 log of C. albicans and showed fewer microscopic lesions of candidiasis than the control group.
Conclusion: The treatment with the essential oil from Melaleuca alternifolia reduced the number of C. albicans in biofilms formed in vitro and in immunossupressed mice candidiasis model.