A new and improved "quick-hot Gram-chromotrope" technique that differentially stains microsporidian spores in clinical samples, including paraffin-embedded tissue sections.

Abstract

This report describes a new and improved "quick-hot Gram-chromotrope" staining technique that detects microsporidian spores in clinical specimens, such as stool, urine, saliva, nasopharyngeal fluid, and bronchoalveolar lavage samples, as well as in formalin-fixed and paraffin-embedded tissue sections. In this procedure, the samples are stained in heated (50 degrees C to 55 degrees C) solutions of crystal violet and iodine used in Gram's stain, followed by a modified chromotrope solution (heated to 50 degrees C to 55 degrees C). The modified stain is composed of chromotrope 2R (1%), fast green (0.15%), and phosphotungstic acid (0.25%). With this stain and the new protocol, microsporidian spores are stained dark violet against a pale green background, and the total staining time is shortened to 5 minutes. This new technique is fast, reliable, and simple. It can be easily adapted for use in clinical laboratories.