The antifungal effect of the essential oil from Satureja montana L., Lavandula angustifolia Mill., Lavandula hybrida Reverchon, Syzygium aromaticum (L.) Merril and Perry, Origanum vulgare L., Rosmarinus officinalis L. and six chemotypes of Thymus vulgaris L. on Candida albicans growth were studied. The most efficiency was obtained with the essential oil from Thymus vulgaris thymol chemotype (MIC 80% = 0.016 microL/mL and Kaff = 296 microL/mL). The presence in the culture medium of essential oil from Thymus vulgaris thymol chemotype (0.01, 0.1, 0.2, 0.3 microg/mL) and amphotericin B involved a decrease of the MIC 80% of amphotericin B. In contrast, the combination of amphotericin B and low concentrations (0.00031-0.0025 microg/mL) of essential oil was antagonistic. The strongest decrease (48%) of the MIC 80% was obtained with medium containing 0.2 microL/mL of essential oil. These results signify that the essential oil of Thymus vulgaris thymol chemotype potentiates the antifungal action of amphotericin B suggesting a possible utilization of this essential oil in addition to antifungal drugs for the treatment of mycoses.

No abstract

Both intrinsic and acquired resistance to amphotericin B have been documented for Candida lusitaniae. Amphotericin B remains the drug of choice for many critical fungal infections, and the detection of resistance is essential to monitor treatment effectively. The limitations of the National Committee for Clinical Laboratory Standards (NCCLS) reference methodology for detection of amphotericin B resistance are well documented, and several alternative methods have been proposed. Etest assays with RPMI and antibiotic medium 3 (AM3) agar were compared to the NCCLS M27-A broth macrodilution method using AM3 for amphotericin B resistance testing with 49 clinical isolates of C. lusitaniae. The panel included nine isolates with known or presumed resistance to amphotericin B on the basis of in vivo and/or in vitro data. The distribution of amphotericin B MICs by Etest with RPMI ranged from 0.032 to 16 g/ml and was bimodal. All of the putatively resistant isolates were inhibited by amphotericin B at >0.38 g/ml and could be categorized as resistant using this breakpoint. Etest with AM3 yielded a broader amphotericin B MIC range (0.047 to 32 g/ml), and there were six putatively resistant isolates for which MICs were >1 g/ml. The separation of putatively susceptible and resistant isolates was less obvious. Broth macrodilution with AM3 generated a unimodal distribution of MICs (ranging from 0.032 to 2 g/ml) and failed to discriminate most of the putatively resistant isolates at both 24 and 48 h. Etest using RPMI and, to a lesser extent, using AM3 provided better discrimination between amphotericin B-resistant and -susceptible isolates of C. lusitaniae.Amphotericin B is the drug of choice for many systemic fungal infections (7). Although rare, treatment failures associated with resistance to amphotericin B or resistance to amphotericin B and azoles in both immunocompromised and immunocompetent patients have been documented (3,13,18). Among the non-Candida albicans species, Candida lusitaniae is of special interest, owing to its uncommon susceptibility pattern (1, 5, 9). Rapidly acquired resistance to amphotericin B has been described or suspected, and some strains of C. lusitaniae may be intrinsically resistant (6, 15). The detection of resistance to amphotericin B is essential for treatment of C. lusitaniae-associated infections. In the past 10 years, there have been major advances in antifungal susceptibility testing, as illustrated by several methodology documents published by the National Committee for Clinical Laboratory Standards (NCCLS) (11). Although standardized NCCLS methods and MIC interpretive breakpoints are now available for azole and flucytosine susceptibility testing of yeasts, amphotericin B testing is still under investigation (4, 11). The methodology initially proposed by the NCCLS, i.e., a broth macrodilution procedure using RPMI 1640 medium, did not consistently detect amphotericin B-resistant isolates, nor does the microdilution format (17). Proposed alternative media and methods include the use of antibi...

The antifungal activity of triterpenoid saponins, with hederagenin or oleanolic acid as aglycone, was investigated in vitro by the agar dilution method. Monodesmosidic hederagenin derivatives were shown to exhibit a broad spectrum of activity against yeast as well as dermatophyte species. alpha-Hederin was the most active compound, and Candida glabrata was the most susceptible strain. The structure-activity relationships are discussed.

The antifungal activity of the essential oil from Cinnamomum cassia, alone or combined with amphotericin B, a drug widely used for most indications despite side-effects was investigated. The composition of the oil was analysed by GC/MS and characterized by its very high content of cinnamaldehyde (92.2%). The minimal inhibitory concentration (MIC 80%), used to evaluate the antifungal activity against Candida albicans, was determined by a macrobroth dilution method followed by a modelling of fungal growth. The essential oil of Cinnamomum cassia exhibited strong antifungal effect (MIC 80% = 0.169 microL/mL and K(aff) = 18,544 microL/mL). A decrease of the MIC 80% of amphotericin B was obtained when the culture medium contained essential oil concentrations ranging from 0.08 to 0.1 microL/mL. The strongest decrease (70%) was obtained when the medium contained 0.1 microL/mL of essential oil. This potentiation of amphotericin B obtained in vitro may show promise for the development of less toxic and more effective therapies especially for the treatment of HIV infection.