title: Use of the fluorochrome calcofluor white in the screening of stool specimens for spores of microsporidia.
abstract: Microsporidia are obligate intracellular protozoal pathogens associated with chronic diarrhea in individuals infected with HIV. Direct detection methods for microsporidial spores in stool include chromotrope-based, fluorochrome, and immunofluorescent stains. The authors compared the ability to detect microsporidial spores in 168 stool specimens using two stains: a chromotrope-based modified trichrome stain and a fluorochrome stain, calcofluor white (Cellufluor, Polysciences, Warrington, PA). In addition to being faster and easier to perform, the calcofluor white stain was found to be more sensitive than the chromotrope-based stain, as 6 of 24 specimens positive by calcofluor white were negative by the chromotrope-based stain on initial smear evaluation. Repeat examination confirmed these six as being positive. To evaluate the specificity of the calcofluor white stain, 20 formalin-fixed stool specimens (5 positive and 15 negative for microsporidial spores) were evaluated in blinded fashion by two affiliated clinical laboratories using their own formulations of calcofluor white. A single discrepant result (falsely positive) was reported from one laboratory. The use of the calcofluor white stain is recommended as a simple and highly sensitive screening procedure for the detection of microsporidial spores in stool specimens.
authors.affiliation: Department of Laboratory Medicine, University of Washington Medical Center, Seattle 98195, USA.
authors.forename: V A
authors.initials: VA
authors.lastname: Luna
authors.forename: B K
authors.initials: BK
authors.lastname: Stewart
authors.forename: D L
authors.initials: DL
authors.lastname: Bergeron
authors.forename: C R
authors.initials: CR
authors.lastname: Clausen
authors.forename: J J
authors.initials: JJ
authors.lastname: Plorde
authors.forename: T R
authors.initials: TR
authors.lastname: Fritsche
mesh_terms: D000818:Animals; D001557:Benzenesulfonates; D005243:Feces / Q000382:microbiology*; D005456:Fluorescent Dyes; D016816:Microsporida / Q000302:isolation & purification*; D013170:Spores; D013194:Staining and Labeling
chemical_list: D001557:Benzenesulfonates; D005456:Fluorescent Dyes; C007061:C.I. Fluorescent Brightening Agent 28