IDENTIFICATION OF CANDIDA SPECIES BY RANDOMLY AMPLIFIED POLYMORPHIC DNA-FINGERPRINTING OF COLONY LYSATES

We have characterized a method that produces simple yet diagnostic fin gerprints that are unique to isolates of Candida species. DNA from ind ividual colonies can be amplified from crude single-colony lysates. Ra ndomly amplified polymorphic DNA (RAPD) fingerprints generated from a single primer correctly identified the species of most (>98%) of the i solates identified with CHROMagar Candida plates as non-Candida albica ns Candida species. RAPD fingerprints were much more informative than the plates, since they distinguished between all tested species and re quired less time. Most (91%) of these identifications agreed with thos e assigned by API 20C tests. In almost every incident of species ident ity mismatch, electrophoretic karyotyping showed that the RAPD fingerp rint was correct. This underscores the improved objectivity and reliab ility of this method over those of conventional diagnostic tools. The identities of approximately 30% of C. albicans isolates identified in clinical laboratories by positive germ tube tests are not verified by either testing on CHROMagar Candida plates or RAPD fingerprinting. Dat a suggest that clinical isolates conventionally identified as C. albic ans in clinical settings are heterogeneous, consisting of both misiden tified and atypical yeasts. RAPD fingerprints obtained from primary cu lture plate colonies allows for rapid, highly accurate determinations of Candida species, hence permitting earlier selection of appropriate antifungal agents in the clinical setting.