Contribution to the knowledge of the enzymatic activity of yeasts of clinical interest

The determination of the enzymatic activity of the yeasts has been applied to the identification of species, specially that of Candida albicans. In order to know its usefulness in species of clinical interest, we have tested the commercial system API ZYM (Bio Merieux) on 500 isolated strains of different organic samples, belonging to eight genera and twenty species. All the strains showed positivity to Phosphatase alcaline, Esterase (C4), Esterase lipase (C8), Leucine arylamidase and Phosphatase acid, and negativity to Lipase (C14), Trypsin, Chymotrypsin, alpha-galactosidase, beta-glucoronidase, alpha-manosidase and alpha-fucosidase. Fourteen enzymatic activity patterns were obtained considering the substrates with variable results for the whole of the strains: Valine arylamidase, Cystine arylamidase, Naphthol-AS-BI-phosphohydrolase, beta-galactosidase, alpha-glucosidase, beta-glucosidase and N-acetyl-beta-glucosaminidase. In the majority of the species, the enzymatic profile did not have very specific results since it is usually shared by more than one species. C. albicans is that which presents the greatest number of enzymatic variations, some of these are similar to those of other common clinical species, such as Candida krusei, Candida parapsilosis and Candida tropicalis. This system is proposed as a rapid method for identification and as an epidemiological marker of medically important yeasts.