This procedure is employed to observe capsule around the yeasts especially Cryptococcus neoformans in CSF. Some bacteria with capsule eg klebsiella stain with Indian ink but are one fourth the size of yeast and are not budding.
Indian ink is used as definitive evidence of Cryptococcus neoformans but other studies such as dark brown pigment production on caffeic acid agar, direct antigen testing are also used.
1. Place a small drop of India ink on a grease free slide containing the test sample
Process different specimens as follows:
2. Fluid samples like CSF should be centrifuged and the sediment used on the slide.
3. In thick specimens like pus and sputum add drop of 10% KOH along with India ink to improve visualisation.
4. Leukocytes and tissue cells can be dissolved by adding a drop of 10% KOH.
5. Observe under ×10 and confirm by ×40
6. Record the findings
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