[Identification of Candida species of clinical importance by means of a modified auxonographic method]

Candida species are responsible for the most common opportunistic mycotic infections. Rapid and accurate identification of yeast has become relevant not only for the effective management of infections, but also for the prevention of drug resistance. Up to now, yeast identification procedures are based on a variety of tests, including their ability to use sugars.

the purpose of the study was to evaluate a modified auxonographic procedure with the use of carbonated compounds for the rapid identification of Candida species within 24 to 48 h.

the new procedure is based on the carbohydrates assimilation (auxonograph) and was developed and evaluated for the identification of the most clinically relevant Candida species. A total number of 164 Candida species strains were included in the study, 156 of them were isolated from clinical specimens and other 8 reference strains from the central culture collection of BioCen (C. albicans, C. tropicalis. C. parapsilosis, C. glabrata, C. guilliermondii, C. krusei y C. kefyr). The new methodology was based on the use of standardized yeast suspension of carbon-free culture medium sterilized by autoclaving. After gelling the mixture (60 mL of cultural medium and 3 mL of microbial suspension), 10 microL of different carbohydrate filtering-sterilized solutions were dispensed at different points of the culture medium surface. The carbohydrate uptake was seen as a growth zone around the carbohydrate point of distribution after 24-48 h of incubation.

all Candida species were correctly identified by the modified auxonographic method and 100 % agreement with the Wickerham technique was achieved.

the alternative method for the auxonographic carbon test is simple, reliable, faster and easier to interpret than the Wickerham method.