CANDIDA-ALBICANS SEROTYPE ANALYSIS BY FLOW-CYTOMETRY

Candida albicans strains can be assigned to either of two major serogr oups, A or B. Antigenic surface determinants present only in serotype A strains allow such a distinction, which has epidemiologic relevance. Reports have established that the relative distributions of the two s erotypes can vary depending on the geographic origin of the isolates, A prevalence of susceptibility to an antifungal agent, flucytosine, wa s also observed with isolates of serotype A, More recently, it was sug gested that the occurrence of serotype B isolates in various clinical forms of candidiasis is increasing. However, this latest finding remai ns controversial since serotyping results vary widely from one laborat ory to another because of the lack of standardized methodologies, Diff iculty in interpretation of results, which may lead to erroneous serot ype identification, is the major setback associated with current metho ds, For this study, we thus devised a procedure that relies on flow cy tometry and that may eliminate ambiguities in serotype determination. The validation of results was achieved with two types of serotype A-sp ecific antisera, Iatron Factor 6 antiserum and an anti-C, albicans ant iserum adsorbed on serotype B yeast cells, Agreement between results o btained with these two reagents was 100% with a nide array of Candida strains. These results confirmed the potential of the flow cytometric procedure as a reliable and reproducible method to establish the serot ypes of C, albicans strains. Furthermore, some applications of this pr ocedure to the epidemiological study of this human pathogen are presen ted.