Discrimination between the enzymatic activities of Candida albicans pleomorphic forms determined using the api® ZYM test

Abstract

Enzymatic activity profiles for two morphotypes of 37 Candida albicans clinical isolates were compared. Yeast and hyphal forms were grown using yeast extract-peptone-glucose broth or undiluted human serum, respectively. Both morphotypes were documented under scanning electron microscopy. The api(®) ZYM (BioMérieux, France) test was used to evaluate the enzymatic activity profiles for particular pleomorphic forms. None of the examined enzymatic activities showed good agreement (kappa, κ > 0.80) for the two morphotypes of the tested strains. Only leucine arylamidase activity in blastoconidia and hyphae of 35 out of 37 strains appeared to be in significant agreement (κ = 0.770). This phenomenon should be explored further for clinical benefits. For morphotypes of all tested strains, activity profiles of 11 hydrolytic enzymes demonstrated weak agreement (κ = 0.044-0.197). Moreover, satisfactory (κ = 0.218-0.348) and moderate agreement (κ = 0.413-0.479) were noted for enzymatic activity values of five and two enzymes, respectively. The distinct differences in activity profiles of hydrolytic enzymes between hyphae and blastoconidia is suggested to be related to the specific roles of these two morphotypes in particular steps of pathogenesis. Moreover, both morphotypes should be examined by strain biotyping methods. Beta-N-hexosaminidase (HexNAcase) activity assessed by the api(®) ZYM test and on CHROMagar Candida(®) medium (Becton Dickinson, USA) is also discussed.