Identification of dermatophytes by an oligonucleotide array.
Species of dermatophytes are classified into three anamorphic (asexual) genera, Epidermophyton, Microsporum, and Trichophyton. Conventional methods used to identify dermatophytes are often lengthy and may be inconclusive because of atypical microscopic or colony morphology. Based on the internal transcribed spacer 1 (ITS-1) and ITS-2 sequences of the rRNA genes, an oligonucleotide array was developed to identify 17 dermatophyte species. The method consisted of PCR amplification of the ITS regions using universal primers, followed by hybridization of the digoxigenin-labeled PCR products to an array of oligonucleotides (17- to 30-mers) immobilized on a nylon membrane. Of 198 dermatophyte strains and 90 nontarget strains tested, the sensitivity and specificity of the array were 99.5% and 97.8%, respectively. The only strain not identified (Microsporum audouinii LMA 597) was found to have a nucleotide insertion at the ITS-2 region where the probe was designed. Two nontarget strains, Microsporum equinum LMA 40396666 and Trichophyton gourvilii var. intermedium CBS 170.65, were misidentified as Microsporum canis and Trichophyton soudanense, respectively. Sequence analysis of the ITS regions revealed that the two misidentified strains displayed high sequence homology with the probes designed for M. canis and T. soudanense, respectively. The present method can be used as a reliable alternative to conventional identification methods and can be completed with isolated colonies within 24 h.
Department of Medical Laboratory Science and Biotechnology, School of Medicine, National Cheng Kung University, 1 University Road, Tainan 701, Taiwan, Republic of China.
Hsin Chieh
HC
Li
Jean-Philippe
JP
Bouchara
Mark Ming-Long
MM
Hsu
Richard
R
Barton
Tsung Chain
TC
Chang
D003883:Arthrodermataceae / Q000235:genetics / Q000302:isolation & purification*; D021903:DNA, Ribosomal Spacer / Q000737:chemistry; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D015345:Oligonucleotide Probes; D012680:Sensitivity and Specificity
D021903:DNA, Ribosomal Spacer; D015345:Oligonucleotide Probes