PCR IDENTIFICATION OF 4 MEDICALLY IMPORTANT CANDIDA SPECIES BY USING A SINGLE PRIMER PAIR

A single pair of primers was used in a PCR assay to amplify and identify the DNAs from four medically important Candida species: C. albicans, C. parapsilosis, C. tropicalis, and C. (Torulopsis) glabrata. The report describes the first successful amplification of a chitin synthase-specific fragment from the four Candida species responsible for more than 90% of all cases of neonatal candidemia. The primer pair sequence was based on that from the C. albicans chitin synthase gene, CHS1 (J. Au-Young and P. W. Robbins, Mol. Microbiol. 4:197-207, 1990). Each of the four amplified products is a single band of a different size. The DNA sequence of each PCR product was determined, and four species-specific probes were synthesized. The DNAs from as few as 10 organisms in 100 mu l of plasma could be detected after amplification and Southern blot analysis. In a retrospective study of 27 paired blood samples from 16 patients with culture-proven candidemia, PCR analysis was successful at detecting and correctly identifying to the species level 26 of the 27 Candida isolates. The speed and accuracy of this PCR-based technology make it a very powerful tool for detecting and diagnosing candidemia. Implementation of this assay for analyzing blood samples should result in the more timely treatment of neonatal candidemia, thereby reducing morbidity and mortality.