RAPID DIFFERENTIATION OF CLOSELY-RELATED CANDIDA SPECIES AND STRAINS BY PYROLYSIS MASS-SPECTROMETRY AND FOURIER TRANSFORM-INFRARED SPECTROSCOPY

Two rapid spectroscopic approaches for whole-organism fingerprinting o f pyrolysis-mass spectrometry (PyMS) and Fourier transform-infrared sp ectroscopy (FT-IR) were used to analyze a group of 29 clinical and ref erence Candida isolates. These strains had been identified by conventi onal means as belonging to one of the three species Candida albicans, C. dubliniensis (previously reported as atypical C. albicans), and C. stellatoidea (which is also closely related to C. albicans), To observ e the relationships of the 29 isolates as judged by PyMS and PT-IR, th e spectral data were clustered by discriminant analysis. On visual ins pection of the cluster analyses from both methods, three distinct clus ters, which were discrete for each of the Candida species, could be se en. Moreover, these phenetic classifications were found to be very sim ilar to those obtained by genotypic studies which examined the Hinfl r estriction enzyme digestion patterns of genomic DNA and by use of the 27A C. albicans-specific probe, Both spectroscopic techniques are rapi d (typically, 2 min for PyMS and 10 s for FT-LR) and were shown to be capable of successfully discriminating between closely related isolate s of C. albicans, C. dubliniensis, and C. stellatoidea. We believe tha t these whole-organism fingerprinting methods could provide opportunit ies for automation in clinical microbial laboratories, improving turna round times and the use of resources.