Wheatley Trichrome Staining


Wheatley Trichrome Staining is a special permanent staining technique used in parasitology for the detection and identification of intestinal protozoans from stool samples. Protozoans are single-celled organisms that can cause various diseases in humans and animals, such as amoebiasis, giardiasis, and trichomoniasis. Wheatley Trichrome Staining helps to visualize the different morphological forms of protozoans, such as cysts and trophozoites, by staining them with different colors.

Wheatley Trichrome Staining is a modified version of Gomori`s original trichrome staining method, which was developed for staining tissues. Wheatley simplified and improved the procedure by adding fixative and hydration steps, and reducing the staining time. Wheatley Trichrome Staining produces uniformly stained smears of intestinal protozoans, yeasts, artifacts, and human cells, with a high contrast between the background and the organisms.

Wheatley Trichrome Staining is performed on stool samples that are either fresh or fixed in polyvinyl alcohol (PVA) or sodium acetate-acetic acid-formalin (SAF). The stool samples are smeared on microscopic slides and stained with a solution containing chromotrope 2R, light green SF, phosphotungstic acid, and acetic acid. The staining solution colors the cytoplasm of protozoan trophozoites blue-green or light purple, and the cysts more purple. The nuclei and inclusion bodies stain red with a tinged purple. The background stains green. The stained smears are then examined under a microscope at high magnification to identify the protozoans.

Wheatley Trichrome Staining is a sensitive and rapid technique that can detect small protozoans that may be missed during wet mount examination. It is also useful for identifying different yeast cells and human cells in stool samples. However, Wheatley Trichrome Staining has some limitations, such as not being able to stain helminth eggs and larvae, Cryptosporidium parvum, Cyclospora cayetanensis, and microsporidia spores. Therefore, other staining techniques may be required to complement Wheatley Trichrome Staining for a comprehensive diagnosis of intestinal parasitic infections.