robin082006
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D, Cryptococcus neoformans infection
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| pocas
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D encapsulated monomorphic
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| pocas
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D encapsulated monomorphic
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| 26malik
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The correct answer is D .
This patient has cryptococcal meningitis, as evidenced by the "encapsulated organisms observable with India ink" in the CSF (a classic clue). Cryptococcus is a nondimorphic yeast, meaning that it exists only in the yeast form. It is encapsulated (that's why the India ink stain works so well) and it reproduces by budding. It is found worldwide in bird droppings (think pigeons). It can also cause transient pulmonary
illness in otherwise healthy individuals.
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| zaidsuror
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D
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| ts97
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A, GMS stain are typically used to detect fungal organisms
Not D: because cryptococcus IS dimorphic
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| pocas
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 no t 97 the cyptococcus is polisaccharide encapsulated yeast NOT DIMORFIC , CHECK YOUR NOTES
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| ts97
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Why not A then?
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| bactitech
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Cryptococcus neoformans is NOT a dimorph. An India Ink preparation shows the capsule quite nicely. However, a much more sensitive test for this organism is a Cryptococcal antigen. If you are suspicious of this organism, I highly suggest you have this test done in addition to culturing for bacteria and fungi in a CSF. Titers are used on positive antigens to follow treatment in infected patients.
A silver stain will not identify this organism per se. It will just show a big fat yeast! We get 1-2 positives a year at our large micro lab. Smaller labs see this organism even less often.
I have seen positive India Ink preps - they are quite breathtaking to see if you don't suspect a positive and they look JUST LIKE the textbook pictures. The trick is to put a drop of CSF sediment down, then put a drop of India Ink next to it (not touching). Then coverslip and read the interface of the ink and CSF. You will get a nice gradient where you can see the yeasts.
Interestingly, if you take some C. neoformans on a plate and make an II prep from it, you won't always get the nice capsule. They lose the capsule sometimes after being subcultured. We ended up buying commercial positive controls, as we couldn't get our yeast to make capsules any more.
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| Diego Casali
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The right answer is D.
No doubt.
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