Bailey & Scott's Diagnostic Microbiology: Laboratory Techniques in Mycology Direct Exam-Specialized Stains Flashcards


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1

methenanamine silver stain

used to identify mucopolysaccharides in tissues including fungi or Pneumocystis jiroveci; used in place of PAS; chromic acid oxidation forms aldehydes from fungal cell wall polysaccharide components, reducing alkaline hexamine-silver complex; Grocott's alkaline hexamine-silver solution represents vehicle, precipitating nascent silver ions causing blackening-known as argentaffin reaction

2

hematoxylin and eosin (H&E) stain

routine histopathological stain used to examine tissues; alum acts as mordant and hematoxylin containing alum stains nucleus light blue; acid turns this red, bluing step converts initial soluble red color within nucleus to an insoluble blue color; counterstain completed by eosin; tissue section used for QC

3

auramine-rhodamine stian

nonspecific histological stain used to screen for acid-fast organisms; fluorochrome dye forms complex with mycolic acids found in acid fast cell wall of organisms resisting decolorization by acid-alcohol; counterstain potassium permanganate reduces artifact; visualized under UV light appearing bright yellow or reddish orange; positive-acid fast organisms fluoresce reddish-orange against dark background, negative-non acid fast do not fluoresce and appear pale yellow

4

Masson-Fontana stain

silver based histochemical stain used to demonstrate melanin and argentaffin granules in neuroendocrine cells; argentaffin cell granules and melanin stain black, nuclei stain pink-red, cytoplasm pale pink; positive-hair, skin for melanin, and small intestine for argentaffin

5

India Ink capsule stain

used to demonstrate cell capsules; detects presence of Cryptococcus; acidic (negatively charged) dye will not stain cells, but produces halo around negatively charged cells