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Differentiation of Fusarium from Aspergillus species by colorimetric in situ hybridization in formalin-fixed,

Kathleen T Montone1

  • 1Dept of Pathology and Laboratory Medicine, Hospital of University of Pennsylvania, 3400 Spruce St, 6 Founders, Philadelphia, PA 19104, USA.

American Journal of Clinical Pathology
|November 21, 2009
PubMed

Insights

A new ribosomal RNA (rRNA) in situ hybridization (ISH) method rapidly distinguishes between Fusarium and Aspergillus fungal pathogens in tissue samples. This molecular diagnostic tool aids identification, especially when cultures are negative.

Area of Science:

  • Medical Mycology
  • Molecular Diagnostics
  • Pathology

Background:

  • Fusarium and Aspergillus are fungal pathogens causing severe diseases, particularly in immunocompromised individuals.
  • Distinguishing between these fungi in tissue sections is diagnostically challenging using conventional methods.

Purpose of the Study:

  • To develop a rapid and accurate method for differentiating Fusarium and Aspergillus in formalin-fixed, paraffin-embedded tissue sections.
  • To establish an in situ hybridization (ISH) protocol for identifying fungal pathogens in surgical pathology.

Main Methods:

  • Development of a rapid (<3 hours) ribosomal RNA (rRNA) in situ hybridization (ISH) protocol.
  • Utilized dual fluorogenic-labeled oligonucleotide probes containing a mixture of DNA and locked nucleic acids (LNAs).
  • Applied the ISH assay to formalin-fixed, paraffin-embedded tissue sections.

Main Results:

  • The developed ISH assay successfully differentiated between Aspergillus and Fusarium in tissue samples.
  • The protocol demonstrated high specificity and speed, completing within 3 hours.

Conclusions:

  • Ribosomal RNA (rRNA) in situ hybridization (ISH) is effective for identifying fungal pathogens in surgical pathology.
  • This LNA-enhanced ISH method offers a valuable tool for diagnosing fungal infections when cultures are unavailable or negative.

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