Originally Posted by Tonino
First timer here. Not sure if this is where I can post questions regarding theory tested on the step 1, but I've got a question.
Why does India ink specify for cryptococcus? I imagine this would create a "halo" around any encapsulated cell. Is it because the cryptococcus has a particularly thick capsule?
India ink stains the capsule. It is not specific for Cryptococcus, but when you know it is a fungus (i.e. grows on Sabouraud agar), there are not that many choices. Since it's Cryptococcus we are most likely talking about meningitis. When it's fungal meningitis, you need to differentiate between Cryptococcus, Candida and Histoplasma (as most likely fungi causing meningitis). Only Cryptococcus has that large polysaccharide capsule that can be visualised with ink stain.