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Multilocus DNA sequence comparisons rapidly identify pathogenic molds

Jennifer L Rakeman1, Uyen Bui, Karen Lafe

  • 1Department of Laboratory Medicine, University of Washington, Box 357110, Seattle, WA 98195, USA.

Journal of Clinical Microbiology
|July 8, 2005
PubMed

Insights

DNA sequencing of internal transcribed spacer (ITS) regions rapidly and accurately identifies medically important molds, overcoming limitations of traditional methods. This molecular approach aids in diagnosing fungal infections and discovering new species.

Area of Science:

  • Medical Mycology
  • Molecular Biology
  • Clinical Diagnostics

Background:

  • Opportunistic fungal infections are increasing, requiring rapid and accurate fungal identification for effective patient treatment.
  • Traditional phenotypic identification methods in clinical labs are limited by the need for observable reproductive structures, hindering identification in many cases.

Purpose of the Study:

  • To evaluate the utility of DNA sequence analysis of multiple loci for the rapid identification of medically important molds.
  • To establish a phenotypically validated database of internal transcribed spacer (ITS) sequences for fungal identification.

Main Methods:

  • Analysis of the D1/D2 region of the 28S ribosomal gene and the internal transcribed spacer (ITS) regions 1 and 2 of the rRNA operon.
  • Examination of 201 fungal strains, including clinical isolates and reference strains, representing 43 recognized species and one potential new species.
  • Generation of a phenotypically validated database of 118 diagnostic alleles.

Main Results:

  • Internal transcribed spacer (ITS) DNA sequence analysis identified all 44 species tested, while DNA length polymorphisms differentiated 20 of 33 mold species.
  • Conspecific strains showed >99% sequence identity at ITS1 and ITS2 for 42 of 44 species, with sequevars detected in two species.
  • Genotypic and traditional phenotypic identifications were 100% concordant for all 44 species, and ITS sequences provided phylogenetically valid information.

Conclusions:

  • Internal transcribed spacer (ITS) DNA sequence analysis is a reliable and rapid method for identifying clinically important molds, complementing traditional methods.
  • The phenotypically validated ITS sequence database is valuable for identifying known pathogenic molds and discovering new species.
  • Molecular identification using ITS sequences offers a significant advancement in managing opportunistic fungal infections.

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