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BioMed Research International
Volume 2015, Article ID 938721, 11 pages
http://dx.doi.org/10.1155/2015/938721
Research Article

Detection of Tropical Fungi in Formalin-Fixed, Paraffin-Embedded Tissue: Still an Indication for Microscopy in Times of Sequence-Based Diagnosis?

1Department of Tropical Medicine at the Bernhard Nocht Institute, German Armed Forces Hospital of Hamburg, Bernhard-Nocht Street 74, 20359 Hamburg, Germany
2Institute for Microbiology, Virology and Hygiene, University Medicine Rostock, Schillingallee 70, 18057 Rostock, Germany
3Central Laboratory Department/Department of Clinical Chemistry, University Medicine Goettingen, Robert Koch Street 40, 37075 Göttingen, Germany
4Department of Infectious Disease Pathology, Bernhard Nocht Institute for Tropical Medicine Hamburg, Bernhard Nocht Street 74, 20359 Hamburg, Germany
5LADR GmbH MVZ Dr. Kramer & Kollegen, Lauenburger Straße 67, 21502 Geesthacht, Germany

Received 21 October 2014; Revised 27 February 2015; Accepted 9 March 2015

Academic Editor: Rosely Zancope-Oliveira

Copyright © 2015 Hagen Frickmann et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. The aim of the study was the evaluation of panfungal PCR protocols with subsequent sequence analysis for the diagnostic identification of invasive mycoses in formalin-fixed, paraffin-embedded tissue samples with rare tropical mycoses. Materials and Methods. Five different previously described panfungal PCR/sequencing protocols targeting 18S and 28S ribosomal RNA gene fragments as well as internal transcribed spacer 1 and 2 fragments were evaluated with a collection of 17 formalin-fixed, paraffin-embedded tissue samples of patients with rare and/or tropical invasive mycoses, comprising chromoblastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, mucormycosis, mycetoma/maduromycosis, and rhinosporidiosis, in a proof-of-principle analysis. Results. The primers of the panfungal PCRs readily and predominantly reacted with contaminating environmental fungi that had deposited on the paraffin blocks. Altogether three sequence results of histoplasmosis and mycetoma samples that matched the histological assessment were associated with sample age <10 years and virtually without PCR inhibition. Conclusions. The high risk of amplifying environmental contaminants severely reduces the usefulness of the assessed panfungal PCR/sequencing protocols for the identification of rare and/or tropical mycoses in stored formalin-fixed, paraffin-embedded tissues. Histological assessment remains valuable for such indications if cultural differentiation is impossible from inactivated sample material.