Table 2

Outline of stains used in histopathological evaluation

S.No

Stain

Morphological features

Remarks

1

Hematoxylin and Eosin

pale pink, ill-defined morphology

Most common tissue stain, should raise the suspicion of microsporidia. Appearance may resemble yeasts, needs confirmation by other stains

2

PAS

pink to purple in colour, ill defined morphology

Poorly stained, but the pink dot at the pole could suggest microsporidia. Not confirmatory

3

Giemsa

stain not taken up be cell wall, appears blue,

Stains the organism blue, but does not stand out against the blue background with also shows granular debris Easy to perform

4

GMS

oval to round, brown in colour, internal band is easily spotted, background green

Good stain, highlights the organism again the background under low magnification. Expensive reagents, time consuming

5

CFW

blue, oval, diffusely fluorescing spores, sometimes only spore wall fluoresced

Easy for experienced observer, but can be confused for yeasts. Produces high background noise

Cannot be done without a fluorescence microscope

6

Acridine orange

oval, refractile, yellowish-green to orange fluorescence, no demarcation from the background

Easy for experienced observer, but can be confused for yeasts. Produces high background noise

Cannot be done without a fluorescence microscope

7

Gram

gram variable, waist band visible, poor contrast from background, plenty of inflammatory debris

Economical, easy to perform. Variable staining, high background noise is a limitation. Microbiologists find it familiar and easy to extrapolate with cytologic findings

8

Masson's Trichrome

spores appeared red against a blue background, ill-defined internal morphology

High background noise, difficult to standardize the stain. Pathologists familiarity more than microbiologists

9

1% acid fast

oval, bright red with a darkly stained belt across the spore, visible against a blue background

Good contrast, easy interpretation, less time and economical. Unstained forms can also be found

10

Gram's chromotrope

spores appear purple to pink against green background, characteristic belt visible

Provides good contrast, easy to detect the organism under lower magnification. Has the added advantage of Grams and Massons trichrome, less time

Joseph et al. BMC Clinical Pathology 2006 6:6   doi:10.1186/1472-6890-6-6