Treatment options for aspergillosis include amphotericin B (AMB) and azole compounds, such as voriconazole and itraconazole (ITZ). However, there have been severe side effects associated with these antifungal agents, and antifungal resistance continues to increase.Essential oils (EOs), a mixture of volatile compounds with well-known antifungal activity, have been used to treat human infections and other maladies for centuries. In this study,we present the antifungal screening of 13 EOs against A.flavus, A.fumigatus, and A.niger. AMB and ITZ were used as comparator antifungal agents. A collection of commercially-available EO has been screened for antifungal activity against different clinical fungi AMB-resistant and ITZ-resistant strains: 1A.flavus, 7A.fumigatus, and 5A.niger. EOs were obtained from Flora (Italy). AMB and ITZ were purchased from Sigma-Aldrich (Italy). The chemical composition of the EOs was analysed by Gas Chromatography–Mass Spectrometry(GC/MS). The EOs antifungal activity was determined by a microdilution method, a vapor contact assay, and a disk diffusion assay.We evaluated the Minimum Inhibitory Concentration (MIC) and the Minimum Fungicidal Concentration (MFC) of EOs and drugs according to the CLSI M38-A2 with some modifications for EOs.The final concentrations ranged from 1% to 0.0078% (v/v) for EOs. AMB and ITZ were used as positive controls. Geranium, citronella, and clove were found to be the EOs with the better activity against all fungi tested.In fact, the MICs value of geranium and citronella EOs were 0.06% against A.fumigatus and A.niger (MFC=0.5%).The MIC value of clove EO was 0.125% against A.flavus, A.fumigatus and A.niger (MFC=0.5%).The volatile vapor of geranium, citronella, and clove EOs at 0.075% concentration completely inhibited the growth of all Aspergillus tested.Disk diffusion assay confirm antifungal activity of these 3 EOs, showing mycelial growth inhibition. These data encourage adequately controlled and randomized clinical investigations. Moreover, the use of OEs could be a valid support to limit the spread of resistance (including recovery of resistant isolates from the environment), likely related to the use of fungicides in numerous agricultural practices and commercial products.
Liquid-, Solid- and vapor-phase antifungal activities of thirteen essential oils: susceptibility of selected Aspergillus spp. strains.
Mandras N;Roana J;Pica D;Menotti F;Comini S;Cuffini AM;Tullio V
2019-01-01
Abstract
Treatment options for aspergillosis include amphotericin B (AMB) and azole compounds, such as voriconazole and itraconazole (ITZ). However, there have been severe side effects associated with these antifungal agents, and antifungal resistance continues to increase.Essential oils (EOs), a mixture of volatile compounds with well-known antifungal activity, have been used to treat human infections and other maladies for centuries. In this study,we present the antifungal screening of 13 EOs against A.flavus, A.fumigatus, and A.niger. AMB and ITZ were used as comparator antifungal agents. A collection of commercially-available EO has been screened for antifungal activity against different clinical fungi AMB-resistant and ITZ-resistant strains: 1A.flavus, 7A.fumigatus, and 5A.niger. EOs were obtained from Flora (Italy). AMB and ITZ were purchased from Sigma-Aldrich (Italy). The chemical composition of the EOs was analysed by Gas Chromatography–Mass Spectrometry(GC/MS). The EOs antifungal activity was determined by a microdilution method, a vapor contact assay, and a disk diffusion assay.We evaluated the Minimum Inhibitory Concentration (MIC) and the Minimum Fungicidal Concentration (MFC) of EOs and drugs according to the CLSI M38-A2 with some modifications for EOs.The final concentrations ranged from 1% to 0.0078% (v/v) for EOs. AMB and ITZ were used as positive controls. Geranium, citronella, and clove were found to be the EOs with the better activity against all fungi tested.In fact, the MICs value of geranium and citronella EOs were 0.06% against A.fumigatus and A.niger (MFC=0.5%).The MIC value of clove EO was 0.125% against A.flavus, A.fumigatus and A.niger (MFC=0.5%).The volatile vapor of geranium, citronella, and clove EOs at 0.075% concentration completely inhibited the growth of all Aspergillus tested.Disk diffusion assay confirm antifungal activity of these 3 EOs, showing mycelial growth inhibition. These data encourage adequately controlled and randomized clinical investigations. Moreover, the use of OEs could be a valid support to limit the spread of resistance (including recovery of resistant isolates from the environment), likely related to the use of fungicides in numerous agricultural practices and commercial products.
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