Editing Cryptococcus neoformans (section)

==Characteristics==
[[File:Cryptococcus Gram film.jpg|thumb|left|''C. neoformans'' stained by [[Gram stain]]]]
{{technical|section|date=February 2020}}
''Cryptococcus neoformans'' typically grows as a [[yeast]] (unicellular) and replicates by [[budding]]. It makes [[hypha]]e during mating, and eventually creates [[basidiospores]] at the end of the hyphae before producing spores. Under host-relevant conditions, including low glucose, serum, 5% carbon dioxide, and low iron, among others, the cells produce a characteristic polysaccharide capsule.<ref name="Cryptococcus: From Human Pathogen to Model Yeast, Editors: Joseph Heitman, Thomas R. Kozel, Kyung J. Kwon-Chung, John R Perfect, and Arturo Casadevall">{{cite book |editor1-last=Heitman |editor1-first=Joseph |editor2-last=Kozel |editor2-first=Thomas R. |editor3-last=Kwon-Chung |editor3-first=Kyung J. |editor4-last=Perfect |editor4-first=John R. |editor5-last=Casadevall |editor5-first=Arturo |title=Cryptococcus: From Human Pathogen to Model Yeast |date=2011 |location=Washington, DC |isbn=9781683671220|doi= 10.1128/9781555816858|publisher=ASM Press}}</ref> The recognition of ''C. neoformans'' in Gram-stained smears of purulent exudates may be hampered by the presence of the large gelatinous capsule which apparently prevents definitive staining of the yeast-like cells. In such stained preparations, it may appear either as round cells with Gram-positive granular inclusions impressed upon a pale lavender cytoplasmic background or as Gram-negative lipoid bodies.<ref name="JCM Article">{{cite journal|last1=Bottone|first1=E J|title=Cryptococcus neoformans: pitfalls in diagnosis through evaluation of gram-stained smears of purulent exudates|journal=Journal of Clinical Microbiology|pmc=273699|pmid =6171578| volume=12|issue=6|year=1980|pages=790–1|doi=10.1128/jcm.12.6.790-791.1980}}</ref> When grown as a yeast, ''C. neoformans'' has a prominent capsule composed mostly of [[polysaccharides]]. Under the microscope, the [[India ink]] stain is used for easy visualization of the capsule in cerebral spinal fluid.<ref name="pmid8862601">{{cite journal|last=Zerpa|first=R|author2=Huicho, L |author3=Guillén, A |title=Modified India ink preparation for Cryptococcus neoformans in cerebrospinal fluid specimens.|journal=Journal of Clinical Microbiology|date=September 1996|volume=34|issue=9|pages=2290–1|doi=10.1128/JCM.34.9.2290-2291.1996|pmid=8862601|pmc=229234}}</ref> The particles of ink pigment do not enter the capsule that surrounds the spherical yeast cell, resulting in a zone of clearance or "halo" around the cells. This allows for quick and easy identification of ''C. neoformans''. Unusual morphological forms are rarely seen.<ref name="pmid17642731">{{cite journal|last=Shashikala|author2=Kanungo, R|author3=Srinivasan, S|author4=Mathew, R|author5=Kannan, M|title=Unusual morphological forms of Cryptococcus neoformans in cerebrospinal fluid.|journal=Indian Journal of Medical Microbiology|date=Jul–Sep 2004|volume=22|issue=3|pages=188–90|doi=10.1016/S0255-0857(21)02835-8|pmid=17642731|doi-access=free}}</ref> For identification in tissue, [[mucicarmine stain]] provides specific staining of polysaccharide cell wall in ''C. neoformans''. Cryptococcal antigen from [[cerebrospinal fluid]] is thought to be the best test for diagnosis of cryptococcal meningitis in terms of sensitivity, though it might be unreliable in HIV-positive patients.<ref name="pmid16272534">{{cite journal|last= Antinori|first=Spinello|author2=Radice, Anna |author3=Galimberti, Laura |author4=Magni, Carlo |author5=Fasan, Marco |author6= Parravicini, Carlo |title=The role of cryptococcal antigen assay in diagnosis and monitoring of cryptococcal meningitis.|journal=Journal of Clinical Microbiology|date=November 2005|volume=43|issue=11|pages=5828–9|pmid=16272534|pmc=1287839|doi=10.1128/JCM.43.11.5828-5829.2005|url= https://air.unimi.it/bitstream/2434/6221/2/Antinori.pdf}}</ref>

The first genome sequence for a strain of ''C. neoformans'' (var. ''neoformans''; now ''C. deneoformans'') was published in 2005.<ref name=":1">{{cite journal |author=Coussement |first1=Julien |last2=Heath |first2=Christopher |last3=Roberts |first3=Matthew |last4=Lane |first4=Rebekah |last5=Spelman |first5=Tim |last6=Smibert |first6=Olivia |last7=Longhitano |first7=Anthony |last8=Morrisey |first8=Orla |last9=Nield |first9=Blake |last10=Tripathy |first10=Monica |last11=Davis |first11=Joshua |last12=Kennedy |first12=Karina |last13=Lynar |first13=Sarah |last14=Crawford |first14=Lucy |last15=Slavin |first15=Monica |display-authors= |date=26 May 2023 |title=Current Epidemiology and Clinical Features of Cryptococcus Infection in Patients Without Human Immunodeficiency Virus: A Multicenter Study in 46 Hospitals in Australia and New Zealand |url=https://academic.oup.com/cid/article/77/7/976/7180396 |journal=Clinical Infectious Diseases |volume=77 |issue=7 |pages=976–986 |doi=10.1093/cid/ciad321|pmid=37235212 }}</ref>

Studies suggest that colonies of ''C. neoformans'' and related fungi growing within the ruins of the [[Chernobyl Nuclear Power Plant]] may be able to metabolize [[ionizing radiation]].<ref>{{cite journal|year=2007|title=Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi|journal=PLOS ONE|volume=2|issue=5|pages= e457|doi=10.1371/journal.pone.0000457|pmc=1866175|pmid=17520016|author=Dadachova E|editor1-last=Rutherford|editor1-first=Julian|display-authors=etal|bibcode=2007PLoSO...2..457D|doi-access=free}}</ref>