Repetitive-sequence-PCR-based DNA fingerprinting using the Diversilab system for identification of commonly encountered dermatophytes.
The performance of repetitive-sequence-based PCR (rep-PCR) using the DiversiLab system for identification of dermatophytes commonly isolated in a clinical laboratory was assessed by comparing results to those of conventional tests (colony morphology, microscopic examination of slide cultures, and, for suspected Trichophyton species, use of additional media). Sixty-one cultures were tested in phase 1, the feasibility portion of the study; 64 additional cultures were tested in phase 2, the validation portion conducted to assess reproducibility and confirm accuracy. Discrepancies were resolved by repeating rep-PCR and conventional tests and, in phase 2, sequencing the internal transcribed spacers. After initial testing of the cultures in phase 1 (excluding one contaminated culture), agreement between conventional tests and rep-PCR was 90% (54 of 60). Agreement was 98.3% after resolution of discrepancies, and in all but one case the initial rep-PCR result was correct. After initial testing of cultures in phase 2 (excluding one discarded and one contaminated culture), agreement between rep-PCR and conventional testing was 88.7% (55 of 62). After discrepancies were resolved, agreement was 100%. Initial rep-PCR results were correct, except for one Microsporum canis culture containing two colony variants, which could not be initially identified by rep-PCR. The performance of the DiversiLab system for identification of the dermatophytes commonly encountered in a clinical mycology laboratory-Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton tonsurans, and M. canis-was excellent. Moreover, the DiversiLab system is technically simple and provides results in < 24 h once a pure culture is available for testing, which is considerably more rapid than conventional identification tests.
Pounder
June I
JI
ARUP, 500 Chipeta Way, Salt Lake City, UT 84108, USA. june.pounder@aruplab.com
Williams
Sheri
S
Hansen
Dewey
D
Healy
Mimi
M
Reece
Kristy
K
Woods
Gail L
GL
D003883:Arthrodermataceae / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D016172:DNA Fingerprinting / Q000379:methods; D004271:DNA, Fungal / Q000235:genetics; D003881:Dermatomycoses / Q000175:diagnosis; D006801:Humans; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D013045:Species Specificity
D004271:DNA, Fungal