Detection of fungal organisms in eosinophilic mucin using a fluorescein-labeled chitin-specific binding protein.

Abstract

The ability to identify fungal hyphae in patients with chronic rhinosinusitis (CRS) has been inconsistent. A new fluorescein-labeled staining method targets chitin found in fungal cell walls. We hypothesize that this method would be able to more consistently detect fungi within the mucin of CRS patients. Fifty-four consecutive CRS surgical patients were evaluated. After ensuring sensitivity and specificity of this new method, all specimens were stained with either fluorescein-labeled chitinase or Grocott methanamine silver stain for comparison. All 54 specimens contained eosinophilic mucin on hematoxylin and eosin staining. One or more fungal hyphae could be visualized within the mucin of 54 (100%) of 54 specimens stained using the fluorescein-labeled chitinase. Only 41 (76%) of 54 of the specimens stained with the Grocott methanamine silver stain technique demonstrated fungi. The fluorescein-labeled chitinase-staining technique has greater sensitivity in detecting fungal organisms within eosinophilic mucin. Fungal organisms are present in the mucin of CRS patients.