Combined Antibacterial and Antifungal Activities of Eucalyptus citriodora and Syzygium aromaticum Essential Oils - Supporting Information

Abstract

Background: The increasing proportion of skin infections encountered in general practice represents a substantial level of morbidity. The emergence of multi-drug resistant strains is a formidable threat to the fight against skin diseases and hence alternative forms of treatment are essential. Syzygium aromaticum and Eucalyptus citriodora oils as single entities have demonstrated potency against some of the concerned micro-organisms and any synergistic activity between the two oils could minimise development of resistance by the microorganisms to the two oils.

Objective: The aim of this study was to evaluate for synergism between Eucalyptus citriodora and Syzygium aromaticum essential oils against selected pathogenic microorganisms of the skin.

Materials and methods: Eucalyptus citriodora (eucalyptus oil) and Syzygium aromaticum (clove oil) essential oils were used in this study. In-vitro antimicrobial activities of Sysygium aromaticum and Eucalyptus citriodora oils, alone and in combination were tested against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa, E. coli ATCC 25922, MRSA, Candida albicans, Trichophyton mentagrophytes, Microsporum gypseum and Cryptococcus neoformans.

Results: The combination of the two oils exhibited synergistic activity against Staphylococcus aureus (FICI: 0.240), E. coli (FICI: 0.54), MRSA (FICI: 0.48), and Microsporum gypseum (FICI: 0.36) while the combination exhibited additive activity against Candida albicans (FICI: 2.04).

Conclusion: The combination of clove and eucalyptus oils possesses synergistic activity against most of the test pathogens and therefore may be combined for enhanced antimicrobial activity against a wide range of skin disease-causing microorganisms.

Keywords: antifungal, antibacterial, synergism, Eucalyptus citriodora, Syzygium aromaticum, essential oils