IDENTIFICATION OF PATHOGENIC YEASTS OF THE IMPERFECT GENUS CANDIDA BYPOLYMERASE CHAIN-REACTION FINGERPRINTING

With the increase in the number of immunocompromised hosts, the number of fungal pathogens has increased markedly. Identification and classi fication, especially of yeast species and strains, is often difficult when based solely on phenotypic characteristics. Since it became clear that different fungal pathogens require specific treatment strategies , there is a need for simple, rapid and reliable methods to identify f ungal isolates. Polymerase chain reaction (PCR) fingerprinting was suc cessfully applied here to identify yeast isolates. Microsatellite [(GT G)(5); (GACA)(4)] and minisatellite [(5'GAGGGTGGCGGT-TCT 3'), derived from the core-sequence of the phage M13] specific primers were used as single primers in the PCR to amplify hypervariable interrepeat DNA se quences from over 200 European, American and Australian clinical isola tes within the genus Candida. Each species, represented by its type st rain, could be identified by a specific multilocus pattern, allowing f or the assignment of all the isolates to the appropriate species. Intr a-species variation in the multilocus profiles was about 20% compared to inter-species variation, which was up to 80%. Anamorph-teleomorph p airs could be identified by highly homologous PCR fingerprint patterns . PCR fingerprinting was more discriminatory when compared with routin ely used biochemical tests (Vitek YBC and API ID 32C). PCR fingerprint ing has proven to be a powerful tool for the identification of medical ly important yeasts. It is rapid, sensitive, reliable, highly reproduc ible, stable in vitro and in vivo, and applicable to large-scale exper iments. Potential applications include: yeast taxonomy, epidemiology, environmental surveys, and improvement of the diagnosis of mycotic dis eases.