False-positive results caused by cotton swabs in commercial Aspergillus antigen latex agglutination test.

While testing for Aspergillus spp. using a commercially available latex agglutination test on a brain biopsy wrapped in a cotton swab, false-positive results were obtained. Subsequent application of the test on lavage samples obtained using cotton and synthetic swabs resulted positive with the cotton swabs only. This suggests that epitopes cross-reactive with Aspergillus galactomannan may be present in cotton.