STATISTICAL COMPARISON OF 2 DIFFERENT MET HODS FOR DETERMINING ANTIFUNGAL ACTIVITY

Purpose. When perfecting a new antifungal agent, efficacy evaluation i s based on in vitro tests. Numerous methods have been developed but pr esent standardisation problems, in particular for filamentous fungi. T he amount of glucose consumption in the culture medium allows the fung us growth to be measured. This amount is used to evaluate antifungal e fficacy by comparing the difference of consumption in a treated and un treated fungus. To validate this glucose test, it was compared to the traditional turbidimetric method. Methods. In a Yeast Nitrogen Base li quid medium supplemented with Glucose (YNBG), a Candida albicans strai n was treated with various amphotericin B concentrations. Different in cubation conditions were carried out. After incubation, absorbance and glucose concentration were measured for each sample. Inhibition perce nrages were calculated from both method by comparison with the untreat ed fungus. Results were compared by using the Student t-test (paired s amples method). For the turbidimetric method, a calibration curve betw een absorbance and cell concentration was performed to interpret absor bances superior to 1. Results. The two techniques statistically gave t he same results (p < 0.05) for the study of amphotericin B against a C . albicans strain. Discussion/Conclusion. This glucose test gives part ial inhibition percentages which are useful when azole antifungals are involved. Furthermore, this technique can be used with filamentous fu ngi, for which partial inhibitions are frequent and interpretation of minimum inhibitory concentration values difficult.