Comparison of macro and micro procedures to evaluate the inhibitory activity of pathogenic fungi and yeasts to man

Abstract

Screening for antifungal activity allows in vitro evidence of how a plant extract inhibits fungal growth under standard conditions. Currently, the Faculty of Chemical Sciences and Pharmacy uses the Agar Macrodilution methodology, which utilizes significant amounts of resources, materials, and time. As part of the globalization process, the National Committee for Clinical Laboratory Standardization (NCCLS) approved the plate microdilution technique as a standard for measuring antifungal activity. This technique, using minimal resources, provides results in less time. Despite its approval, it is not yet used in Guatemala for screening or for determining the minimum inhibitory concentration (MIC) of plant extracts. Therefore, the present study aimed to compare both techniques by evaluating 12 commonly used extracts against 4 ATCC strains of uniform yeast fungi and 6 ATCC strains of filamentous fungi, to determine whether the two techniques are comparable. The comparison of both techniques was carried out through a concordance study and with the use of the Student t test for means of two paired samples, it was shown that there is a significant difference between both, since a p value <0.025 was obtained. Thus, it could be concluded that the Microdilution technique in plate cannot yet replace the Macrodilution in agar, but both can be used simultaneously in order to combine their benefits. The fungicidal activity of the ethanolic extract of the 5. americaiutm leaf and the chloroformice extract of the L. graveolens leaf was verified.