Evaluation of the modified API 20C system for identification of clinically important yeasts.

The modified API 20C system (Analytab Products, Inc.) containing 19 carbohydrate assimilation tests was used to identify stock cultures of clinical isolates and routine clinical isolates from the Mayo Clinic mycology laboratory. The system provided correct identifications for 96% of the 505 organisms tested. The API 20C represents a commercial system useful for the identification of yeasts from clinical specimens. Although reliable, it is not a complete system and must be used in conjunction with microscopic morphological features for definitive identification. Since the system requires 72 h for identification, it is not designed for the rapid presumptive identification of such organisms as Cryptococcus neoformans; other biochemical tests must be used for this purpose.