Biology:Cryptococcus gattii
| Cryptococcus gattii | |
|---|---|
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| Cryptococcus neoformans weakly encapsulated (left) as it appears in nature, and (right) rehydrated with thick polysaccharide capsule as it appears once in the lungs | |
Scientific classification 
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| Kingdom: | Fungi |
| Division: | Basidiomycota |
| Class: | Tremellomycetes |
| Order: | Tremellales |
| Family: | Cryptococcaceae |
| Genus: | Cryptococcus |
| Species: | C. gattii
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| Binomial name | |
| Cryptococcus gattii (Vanbreus. & Takashio) Kwon-Chung & Boekhout
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Cryptococcus gattii, formerly known as Cryptococcus neoformans var. gattii, is an encapsulated yeast fungus found primarily in tropical and subtropical climates. Its teleomorph is Filobasidiella bacillispora, a filamentous fungus belonging to the class Tremellomycetes.
C. gattii is one of two organisms causing the infectious disease cryptococcosis (along with C. neoformans).[1] Clinical manifestations of C. gattii infection include pulmonary cryptococcosis (lung infection), basal meningitis, and cerebral cryptococcomas. Occasionally, the fungus is associated with skin, soft tissue, lymph node, bone, and joint infections. In recent years, it has appeared in British Columbia, Canada and the Pacific Northwest.[2] It has been suggested that tsunamis, such as the 1964 Alaska earthquake and tsunami, might have been responsible for carrying the fungus to North America and its subsequent spread there.[3] From 1999 through to early 2008, 216 people in British Columbia have been infected with C. gattii, and eight died from complications related to it.[4] The fungus also infects animals, such as dogs, koalas, and dolphins.[5] In 2007, the fungus appeared for the first time in the United States, in Whatcom County, Washington,[6] and in April 2010 had spread to Oregon.[7] The most recently identified strain, designated VGIIc, is particularly virulent, having proved fatal in 19 of 218 known cases.[8]
Nomenclature
Cryptococcus gattii has recently been divided into five species.[9] These are C. gattii, C. bacillisporus, C. deuterogattii, C. tetragattii, and C. decagattii.
Etymology
The genus name Cryptococcus comes from Ancient Greek κρυπτός (kruptós), meaning "hidden", and κόκκος (kókkos), meaning "grain". The specific name gattii comes from Italian mycologist Franco Gatti.[10]
Environmental microbiology
C. gattii occupies an environmental niche in decaying hollows of trees native to tropical as well as subtropical and temperate regions. It may then contaminate nearby soil or persist in wood products.[1]
Distribution
Soil debris associated with certain tree species has been found frequently to contain C. gattii VGIII MATα and MATa, and less commonly VGI MATα, in Southern California. These isolates were fertile, were found to be indistinguishable from the human isolates by genome sequence, and were virulent in in vitro and animal tests. Isolates were found associated with Canary Island pine (Pinus canariensis), American sweetgum (Liquidambar styraciflua), and Pohutukawa tree (Metrosideros excelsa).[11]
One study concluded "[j]ust as people who travel to South America are told to be careful about drinking the water, people who visit other areas like California, the Pacific Northwest, and Oregon need to be aware that they are at risk for developing a fungal infection, especially if their immune system is compromised."[12]
Epidemiology
C. gattii infections were initially thought to be restricted to tropical[1][13] and subtropical regions.[13] C. gattii is the predominant cause of cryptococcosis in sub-Saharan Africa.[14] The highest incidences of C. gattii infections occur in Papua New Guinea and Northern Australia. However cases have been reported in various other regions including Brazil, India and the Pacific Northwest of North America. The spread of this fungus is hypothesized to be linked to climate change.[15]
The multiple clonal clusters in the Pacific Northwest likely arose independently of each other as a result of sexual reproduction occurring within the highly sexual VGII population.[16] VGII C. gattii have probably undergone either bisexual or unisexual reproduction in multiple different locales, thus giving rise to novel virulent phenotypes.
Pathology
C. gattii is notable for causing cryptococcosis in otherwise healthy persons.[13][1] Unlike Cryptococcus neoformans, C. gattii is not particularly associated with human immunodeficiency virus infection or other forms of immunosuppression. Increased virulence may be related to a capability to rapidly proliferate within lymphocytes.[17]
C. gattii infection is more likely to be limited to the lung (rather than disseminating to the CNS). When CNS infection does occur, it may involve more localised lesions (cryptococcomas) rather than the diffuse infection characteristic of C. neoformans.[13]
Diagnosis
Culture of sputum, bronchoalveolar lavage, lung biopsy, cerebrospinal fluid or brain biopsy specimens on selective agar allows differentiation between the five members of the C. gattii species complex and the two members of the C. neoformans species complex. The optimal growth temperature of C. gattii is 30 °C (86 °F).[18]
Treatment
People who have C. gattii infection need to take prescription antifungal medication for at least 6 months; usually the type of treatment depends on the severity of the infection and the parts of the body that are affected.
- For people who have severe lung infections, or infections in the central nervous system (brain and spinal cord), the treatment is amphotericin B in combination with flucytosine.[19]
References
- ↑ 1.0 1.1 1.2 1.3 Tortora, Gerard J.; Funke, Berdell R.; Case, Christine L. (2021). Microbiology: An Introduction (13th ed.). Harlow: Pearson. p. 665. ISBN 978-1-292-27626-7.
- ↑ "Cryptococcus gattii Q&A". The Globe and Mail. 2007-02-10. https://www.theglobeandmail.com/servlet/story/RTGAM.20070210.wfungusQA0210/BNStory/Front.
- ↑ Johns Hopkins University, Bloomberg School of Health (October 1, 2019). "Did long ago tsunamis lead to mysterious, tropical fungal outbreak in Pacific northwest?". Science X Network. https://phys.org/news/2019-10-tsunamis-mysterious-tropical-fungal-outbreak.html.
- ↑ "Deadly fungus migrates to Vancouver". Vancouver Sun. 2008-02-18. http://www.canada.com/vancouversun/news/story.html?id=e3500943-715a-4577-9554-a7bfe2ba8757&k=39482.
- ↑ Struck, Doug (2007-04-08). "Alien Invasion:The Fungus that came to Canada". The Washington Post. https://www.washingtonpost.com/wp-dyn/content/article/2007/04/07/AR2007040700698.html?hpid=topnews.
- ↑ Rare, deadly tropical fungus moves into Whatcom County | KOMO-TV - Seattle, Washington | Local & Regional
- ↑ "Potentially deadly fungus spreading in U.S. and Canada". Reuters. 22 April 2010. https://www.reuters.com/article/us-fungus-oregon/potentially-deadly-fungus-spreading-in-u-s-and-canada-idUSTRE63L66H20100422.
- ↑ "New, Deadly Cryptococcus Gattii Fungus Found in U.S.". 2010-04-23. http://news.nationalgeographic.com/news/2010/04/100421-new-fungus-cryptococcus-gattii-deadly-health-science/.
- ↑ Hagen, Ferry; Khayhan, Kantarawee; Theelen, Bart; Kolecka, Anna; Polacheck, Itzhack; Sionov, Edward; Falk, Rama; Parnmen, Sittiporn et al. (2015-05-01). "Recognition of seven species in the Cryptococcus gattii/Cryptococcus neoformans species complex". Fungal Genetics and Biology 78: 16–48. doi:10.1016/j.fgb.2015.02.009. ISSN 1096-0937. PMID 25721988. Bibcode: 2015FuGB...78...16H.
- ↑ National Library Of Medicine https://pmc.ncbi.nlm.nih.gov/articles/PMC2958036/
- ↑ Deborah J. Springer; R. Blake Billmyre; Elan E. Filler; Kerstin Voelz; Rhiannon Pursall; Piotr A. Mieczkowski; Robert A. Larsen; Fred S. Dietrich et al. (August 21, 2014). "Cryptococcus gattii VGIII Isolates Causing Infections in HIV/AIDS Patients in Southern California: Identification of the Local Environmental Source as Arboreal". PLOS Pathogens 10 (8). doi:10.1371/journal.ppat.1004285. PMID 25144534.
- ↑ "Fungus deadly to Aids patients grows on trees". Health24. 2014-08-22. http://www.health24.com/Medical/HIV-AIDS/News/Fungus-deadly-to-Aids-patients-grows-on-trees-20140822.
- ↑ 13.0 13.1 13.2 13.3 Sherris Medical Microbiology - 7th Edition.
- ↑ "Dictionnaire médical de l'Académie de Médecine". https://www.academie-medecine.fr/le-dictionnaire/index.php?q=Cryptococcus+gattii.
- ↑ "Climate change & infectious disease: is the future here?". Environmental Health Perspectives 119 (9): a394–a397. September 2011. doi:10.1289/ehp.119-a394. PMID 21885367.
- ↑ Billmyre RB, Croll D, Li W, Mieczkowski P, Carter DA, Cuomo CA, Kronstad JW, Heitman J (Jul 2014). "Highly recombinant VGII Cryptococcus gattii population develops clonal outbreak clusters through both sexual macroevolution and asexual microevolution". mBio 5 (4): e01494–14. doi:10.1128/mBio.01494-14. PMID 25073643.
- ↑ Ma, H; Hagen, F; Stekel, DJ; Johnston, SA; Sionov, E; Falk, R; Polacheck, I; Boekhout, T et al. (4 August 2009). "The fatal fungal outbreak on Vancouver Island is characterized by enhanced intracellular parasitism driven by mitochondrial regulation.". Proceedings of the National Academy of Sciences of the United States of America 106 (31): 12980–5. doi:10.1073/pnas.0902963106. PMID 19651610. Bibcode: 2009PNAS..10612980M.
- ↑ Pettit, Robin; Repp, Kimberly; Hazen, Kevin (2009). "Temperature affects the susceptibility of Cryptococcus neoformans biofilms to antifungal agents" (in en). Medical Mycology 48 (2): 421–426. doi:10.1080/13693780903136879. ISSN 1369-3786. PMID 19637092. http://www.informaworld.com/openurl?genre=article&doi=10.1080/13693780903136879&magic=crossref%7C%7CD404A21C5BB053405B1A640AFFD44AE3.
- ↑ "Clinical Practice Guidelines for Management of cryptococcal Disease: 2010 Update by Infectious Diseases Society of America". http://www.idsociety.org/uploadedfiles/idsa/guidelines-patient_care/pdf_library/cryptococcal.pdf.
Further reading
- "Cryptococcus infection in Tropical Australia". Journal of Clinical Microbiology 42 (8): 3865–3868. 2004. doi:10.1128/jcm.42.8.3865-3868.2004. PMID 15297551.
- Buchanan, Kent; Murphy, Juneann W. (1998). "What Makes Cryptococcus neoformans a Pathogen?". Emerging Infectious Diseases (Centers for Disease Control and Prevention (CDC)) 4 (1): 71–83. doi:10.3201/eid0401.980109. ISSN 1080-6040. PMID 9452400.
- Datta, Kausik; Bartlett, Karen H.; Baer, Rebecca; Byrnes, Edmond; Galanis, Eleni; Heitman, Joseph; Hoang, Linda; Leslie, Mira J. et al. (2009). "Spread of Cryptococcus gattii into Pacific Northwest Region of the United States". Emerging Infectious Diseases (Centers for Disease Control and Prevention (CDC)) 15 (8): 1185–1191. doi:10.3201/eid1508.081384. ISSN 1080-6040. PMID 19757550.
Wikidata ☰ Q149791 entry
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