Rapid Identification ofCandidaSpecies by DNA Fingerprinting with PCR

DNA polymorphisms in different species and strains of the genus Candida were assessed by amplifying genomic DNA with single nonspecific primers. This PCR method employed an arbitrary primer (the 10-mer AP3), a primer derived from the intergenic spacer regions (T3B), and the microsatellite primers (GTG)5and (AC)10. Distinctive and reproducible sets of amplification products were observed for 26 differentCandidaand 8 other fungal species. The numbers and sizes of the amplification products were characteristic for each species.Allyeastspeciestestedcouldbeclearlydistinguishedbytheiramplificationpatterns.Withallprimers, PCRfingerprintsalsodisplayedintraspeciesvariability.However,PCRprofilesobtainedfromdifferentstrains of the same species were far more similar than those derived from different Candida species. By comparing species-specific PCRfingerprints of clinical isolates with those of reference strains, clinical isolates could be identified to the species level even if they could not be identified by routine biochemical methods. The anamorphic yeast genusCandidaincludes many patho- genic species of yeasts that cause a variety of clinical syn- dromes in humans, ranging from superficial infection to inva- sive disease in immunocompromised patients. For compelling prognostic, epidemiological, and therapeutic reasons, it is es- sential to identify accurately the etiological species of a clinical isolate of Candida. Routine procedures for species identifica- tion involve the examination of colony and microscopic mor- phologies and the assessment of various biochemical reactions (50).Commercialcarbohydrateassimilationsystemsarewidely used to identify species of Candida or other genera of medi- cally important yeasts. However, some of the biochemical re- actions ascribed to certain species vary among different strains ofthesamespecies,andconsiderablestrainvariationmaylead