Comparative study of direct polymerase chain reaction, microscopic examination and culture‐based morphological methods for detection and identification of dermatophytes in nail and skin samples

The positive rates of dermatophytes isolated and identified by conventional methods are rather low. Moreover, clinical isolates sometimes show atypical morphology, and in such cases microscopic methods are not applicable for identification. The present study was performed to assess the utility of specific polymerase chain reaction (PCR)‐based methods for Trichophyton rubrum and Trichophyton mentagrophytes as diagnostic tools for dermatophytoses. Both conventional morphological identification and specific PCR methods based on the nuclear ribosomal internal transcribed spacer (ITS)1 DNA sequence were performed to identify dermatophyte species from clinical specimens of patients who visited Kawasaki Social Insurance Hospital between 16 May and 17 August 2005. Specific PCR methods were also directly applied to clinical specimens, and the results of the two methods were compared. The clinical samples examined consisted of 126 skin scale specimens and 80 nail specimens. The positive rates of culture isolation from clinical specimens were 67% and 33% for skin scale and nail specimens, respectively. In contrast, PCR analysis yielded a positive rate of 100% for clinical isolates from both skin scales and nails, and rates of 95% and 99% were obtained by direct application to clinical specimens. The results of the present study indicated that specific PCR is highly advantageous as a diagnostic tool for detection and identification of dermatophytes on direct application to skin scale or nail specimens.

[1]  R. Summerbell,et al.  Forty-Eight-Hour Diagnosis of Onychomycosis with Subtyping of Trichophyton rubrum Strains , 2006, Journal of Clinical Microbiology.

[2]  K. Nishimoto.  [An epidemiological survey of dermatomycoses in Japan, 2002]. , 2006, Nihon Ishinkin Gakkai zasshi = Japanese journal of medical mycology.

[3]  Yayoi Ito,et al.  [Comparative study between culture and PCR-RFLP analysis on identification of the causative agent of Tinea Unguium]. , 2006, Nihon Ishinkin Gakkai zasshi = Japanese journal of medical mycology.

[4]  T. Nishikawa,et al.  Identification of Trichophyton rubrum by nested PCR analysis from paraffin embedded specimen in trichophytia profunda acuta of the glabrous skin. , 2005, Nihon Ishinkin Gakkai zasshi = Japanese journal of medical mycology.

[5]  T. Kasai.  [Statistical study of dermatomycosis for 30 years (1968-1997) in sendai national hospital]. , 2004, Nihon Ishinkin Gakkai zasshi = Japanese journal of medical mycology.

[6]  T. Kanbe,et al.  PCR and PCR-RFLP techniques targeting the DNA topoisomerase II gene for rapid clinical diagnosis of the etiologic agent of dermatophytosis. , 2004, Journal of dermatological science.

[7]  R. Alaghehbandan,et al.  Epidemiology of Dermatophytoses in an Area South of Tehran, Iran , 2004, Mycopathologia.

[8]  M. Muto,et al.  Clinical and mycological study of occult tinea pedis and tinea unguium in dermatological patients from Tokyo , 2003, Mycoses.

[9]  M. Pau,et al.  Tinea pedis observed in Cagliari, Italy, between 1996 and 2000 , 2003, Mycoses.

[10]  R. Baird,et al.  PCR identification of dermatophyte fungi Trichophyton rubrum, T. soudanense and T. gourvilii. , 2002, Journal of medical microbiology.

[11]  K. Makimura,et al.  Species identification system for dermatophytes based on the DNA sequences of nuclear ribosomal internal transcribed spacer 1. , 2001, Nihon Ishinkin Gakkai zasshi = Japanese journal of medical mycology.

[12]  A. Hasegawa,et al.  Cluster Analysis of Human and Animal Pathogenic Microsporum Species and Their Teleomorphic States, Arthroderma Species, Based on the DNA Sequences of Nuclear Ribosomal Internal Transcribed Spacer 1 , 2001, Microbiology and immunology.

[13]  R. Summerbell,et al.  rRNA Gene Internal Transcribed Spacer 1 and 2 Sequences of Asexual, Anthropophilic Dermatophytes Related toTrichophyton rubrum , 1999, Journal of Clinical Microbiology.

[14]  A. Hasegawa,et al.  Phylogenetic Classification and Species Identification of Dermatophyte Strains Based on DNA Sequences of Nuclear Ribosomal Internal Transcribed Spacer 1 Regions , 1999, Journal of Clinical Microbiology.

[15]  C. Jackson,et al.  Species Identification and Strain Differentiation of Dermatophyte Fungi by Analysis of Ribosomal-DNA Intergenic Spacer Regions , 1999, Journal of Clinical Microbiology.

[16]  El Fari,et al.  Identification of common dermatophytes (Trichophyton, Microsporum, Epidermophyton) using polymerase chain reactions , 1998, The British journal of dermatology.

[17]  M. Uehara,et al.  Random amplification of polymorphic DNA is useful for the differentiation of several anthropophilic dermatophytes , 1997, Mycoses.

[18]  R. Baird,et al.  Use of arbitrarily primed polymerase chain reaction to differentiate Trichophyton dermatophytes. , 1996, FEMS microbiology letters.

[19]  K. Makimura,et al.  Detection of a wide range of medically important fungi by the polymerase chain reaction. , 1994, Journal of medical microbiology.

[20]  R. C. Summerbell,et al.  Onychomycosis, Tinea Pedis and Tinea Manuum Caused by Non‐Dermatophytic Filamentous Fungi Nicht‐Dermatophyten‐Fadenpilze als Erreger von Onychomykosen, Tinea pedis und Tinea manuum , 1989, Mycoses.

[21]  Frank T. Boysia.  Medical mycology. The pathogenic fungi and pathogenic actinomycetes , 1982 .

[22]  K. Arndt,et al.  Medical Mycology—The Pathogenic Fungi and the Pathogenic Actinomycetes , 1975 .