OPTIMAL SCREENING AND DIAGNOSIS OF MICROSPORIDA IN TISSUE-SECTIONS - A COMPARISON OF POLARIZATION, SPECIAL STAINS, AND MOLECULAR TECHNIQUES

With improving therapeutic protocols, confirmation of microsporidiosis has become increasingly important. We designed a study to determine t he best screening method(s) for microsporidian detection in biopsy spe cimens. Forty-two small intestinal biopsy specimens from 31 immunocomp romised patients (68% AIDS) were stained (hematoxylin-eosin [H & E], m odified trichrome, Warthin-Starry, and Brown-Brenn) and polarized. Pol ymerase chain reaction and Southern blot assays were performed on all positive cases. Microsporida were detected in nine cases (21%) by modi fied trichrome (all patients with AIDS). Of these, seven were Brown-Br enn positive, and five Warthin-Starry positive. Two cases polarized on H & E and three on special stains. Four of nine positive cases were c onfirmed by molecular studies. We found polarization to be the least s ensitive screening method. The modified trichrome was the most sensiti ve when screening for microsporidiosis in paraffin-embedded biopsy spe cimens. Furthermore, combining Brown-Brenn or Warthin-Starry with the trichrome stain helps exclude false-positive results due to granular a rtifacts (eg. eosinophils, Paneth cells).