An India ink test revealed many encapsulated yeast cells in a centrifuged CSF sample. Which yeast caused the diagnosed meningitis?

The diagnosis of meningitis in this case is attributed to Cryptococcus neoformans due to its distinctive characteristics revealed by the India ink test. This test highlights the presence of large encapsulated yeast cells that are a hallmark of Cryptococcus neoformans.

Cryptococcus neoformans is known for having a prominent polysaccharide capsule, which can be observed under the microscope when mixed with India ink, causing the cells to appear as large round yeasts surrounded by a clear halo of ink that does not penetrate the capsule. This feature is crucial for distinguishing it from other fungi or yeasts that do not exhibit such a prominent capsule.

Other fungi that could be present in the bloodstream or CSF, such as those from the Candida genus, do not typically present this encapsulated morphology, which further emphasizes why the confirmed organism associated with the meningitis in this scenario is specifically Cryptococcus neoformans.

Additionally, while Cryptococcus laurentii is related to the same genus, it is less commonly associated with meningitis in humans and does not share the same prevalence or recognition as a pathogen compared to Cryptococcus neoformans. Thus, the India ink test results strongly indicate the presence of Cryptococcus neoformans as the causative agent of the mening