Cryptococcus gattii

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Cryptococcus gattii
Cryptococcus gattii 02.jpg
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 OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Tremellomycetes
Order: Tremellales
Family: Cryptococcaceae
Genus: Cryptococcus
Species:
C. gattii
Binomial name
Cryptococcus gattii
(Vanbreus. & Takashio) Kwon-Chung & Boekhout

Cryptococcus gattii, formerly known as Cryptococcus neoformans var. gattii, is an encapsulated yeast found primarily in tropical and subtropical climates. Its teleomorph is Filobasidiella bacillispora, a filamentous fungus belonging to the class Tremellomycetes.

Contents

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.

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 ). [10]

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." [11]

Epidemiology

C. gattii infections were initially thought to be restricted to tropical [1] [12] and subtropical regions. [12] C. gattii is the predominant cause of cryptococcosis in sub-Saharan Africa. [13] 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.[ citation needed ]

In the United States, C. gattii serotype B, subtype VGIIa, is largely responsible for clinical cases. The VGIIa subtype was responsible for the outbreaks in Canada; it then appeared in the U.S. Pacific Northwest.[ citation needed ]

According to a CDC summary, from 2004 to 2010, 60 cases were identified in the U.S.: 43 in Oregon, 15 in Washington, and one each in Idaho and California. Slightly more than half of these cases were immunocompromised; 92% of all isolates were of the VGIIa subtype. In 2007, the first case in North Carolina was reported, subtype VGI, which is identical to the isolates found in Australia and California.[ citation needed ]

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. [14] 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 notable for more causing cryptococcosis even in immunocompetent [12] /otherwise healthy individuals. [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 its capability to rapidly proliferate within lymphocytes. [15]

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. [12]

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.

Treatment

Medical treatment consists of prolonged intravenous therapy (for 6–8 weeks or longer) with the antifungal drug amphotericin B, either in its conventional or lipid formulation. The addition of oral or intravenous flucytosine improves response rates. Oral fluconazole is then administered for six months or more.

Antifungals alone are often insufficient to cure C. gattii infections, and surgery to resect infected lung (lobectomy) or brain is often required. Ventricular shunts and Ommaya reservoirs are sometimes employed in the treatment of central nervous system infection.

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.

See also

Related Research Articles

<span class="mw-page-title-main">Basidiomycota</span> Division of fungi

Basidiomycota is one of two large divisions that, together with the Ascomycota, constitute the subkingdom Dikarya within the kingdom Fungi. Members are known as basidiomycetes. More specifically, Basidiomycota includes these groups: agarics, puffballs, stinkhorns, bracket fungi, other polypores, jelly fungi, boletes, chanterelles, earth stars, smuts, bunts, rusts, mirror yeasts, and Cryptococcus, the human pathogenic yeast.

<i>Cryptococcus</i> Genus of fungi

Cryptococcus is a genus of fungi in the family Cryptococcaceae that includes both yeasts and filamentous species. The filamentous, sexual forms or teleomorphs were formerly classified in the genus Filobasidiella, while Cryptococcus was reserved for the yeasts. Most yeast species formerly referred to Cryptococcus have now been placed in different genera. The name Cryptococcus comes from the Greek for "hidden sphere". Some Cryptococcus species cause a disease called cryptococcosis.

<i>Cryptococcus neoformans</i> Species of yeast

Cryptococcus neoformans is an encapsulated yeast belonging to the class Tremellomycetes and an obligate aerobe that can live in both plants and animals. Its teleomorph is a filamentous fungus, formerly referred to Filobasidiella neoformans. In its yeast state, it is often found in bird excrement. Cryptococcus neoformans can cause disease in apparently immunocompetent, as well as immunocompromised, hosts.

<span class="mw-page-title-main">Cryptococcosis</span> Potentially fatal fungal disease

Cryptococcosis is a potentially fatal fungal infection of mainly the lungs, presenting as a pneumonia, and brain, where it appears as a meningitis. Cough, difficulty breathing, chest pain and fever are seen when the lungs are infected. When the brain is infected, symptoms include headache, fever, neck pain, nausea and vomiting, light sensitivity and confusion or changes in behavior. It can also affect other parts of the body including skin, where it may appear as several fluid-filled nodules with dead tissue.

<span class="mw-page-title-main">Fungal infection</span> Disease caused by fungi to animals or humans

Fungal infection, also known as mycosis, is a disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common tinea of the skin, such as tinea of the body, groin, hands, feet and beard, and yeast infections such as pityriasis versicolor. Subcutaneous types include eumycetoma and chromoblastomycosis, which generally affect tissues in and beneath the skin. Systemic fungal infections are more serious and include cryptococcosis, histoplasmosis, pneumocystis pneumonia, aspergillosis and mucormycosis. Signs and symptoms range widely. There is usually a rash with superficial infection. Fungal infection within the skin or under the skin may present with a lump and skin changes. Pneumonia-like symptoms or meningitis may occur with a deeper or systemic infection.

<span class="mw-page-title-main">Opportunistic infection</span> Infection caused by pathogens that take advantage of an opportunity not normally available

An opportunistic infection is an infection caused by pathogens that take advantage of an opportunity not normally available. These opportunities can stem from a variety of sources, such as a weakened immune system, an altered microbiome, or breached integumentary barriers. Many of these pathogens do not necessarily cause disease in a healthy host that has a non-compromised immune system, and can, in some cases, act as commensals until the balance of the immune system is disrupted. Opportunistic infections can also be attributed to pathogens which cause mild illness in healthy individuals but lead to more serious illness when given the opportunity to take advantage of an immunocompromised host.

<span class="mw-page-title-main">Sporotrichosis</span> Medical condition

Sporotrichosis, also known as rose handler's disease, is a fungal infection that may be localised to skin, lungs, bone and joint, or become systemic. It presents with firm painless nodules that later ulcerate. Following initial exposure to Sporothrix schenckii, the disease typically progresses over a period of a week to several months. Serious complications may develop in people who have a weakened immune system.

Immune reconstitution inflammatory syndrome (IRIS) is a condition seen in some cases of HIV/AIDS or immunosuppression, in which the immune system begins to recover, but then responds to a previously acquired opportunistic infection with an overwhelming inflammatory response that paradoxically makes the symptoms of infection worse.

Talaromycosis is a fungal infection that presents with painless skin lesions of the face and neck, as well as an associated fever, anaemia, and enlargement of the lymph glands and liver.

A panzootic is an epizootic that spreads across a large region, or even worldwide. The equivalent in human populations is called a pandemic.

<i>Cochliobolus lunatus</i> Fungal plant pathogen

Cochliobolus lunatus is a fungal plant pathogen that can cause disease in humans and other animals. The anamorph of this fungus is known as Curvularia lunata, while C. lunatus denotes the teleomorph or sexual stage. They are, however, the same biological entity. C. lunatus is the most commonly reported species in clinical cases of reported Cochliobolus infection.

<i>Setosphaeria rostrata</i> Pathogenic fungus

Setosphaeria rostrata is a heat tolerant fungus with an asexual reproductive form (anamorph) known as Exserohilum rostratum. This fungus is a common plant pathogen, causing leaf spots as well as crown rot and root rot in grasses. It is also found in soils and on textiles in subtropical and tropical regions. Exserohilum rostratum is one of the 35 Exserohilum species implicated uncommonly as opportunistic pathogens of humans where it is an etiologic agent of sinusitis, keratitis, skin lesions and an often fatal meningoencephalitis. Infections caused by this species are most often seen in regions with hot climates like Israel, India and the southern USA.

Pathogenic fungi are fungi that cause disease in humans or other organisms. Although fungi are eukaryotic, many pathogenic fungi are microorganisms. Approximately 300 fungi are known to be pathogenic to humans; their study is called "medical mycology". Fungal infections are estimated to kill more people than either tuberculosis or malaria—about two million people per year.

<span class="mw-page-title-main">Mucormycosis</span> Fungal infection

Mucormycosis, also known as black fungus, is a serious fungal infection that comes under fulminant fungal sinusitis, usually in people who are immunocompromised. It is curable only when diagnosed early. Symptoms depend on where in the body the infection occurs. It most commonly infects the nose, sinuses, eyes and brain resulting in a runny nose, one-sided facial swelling and pain, headache, fever, blurred vision, bulging or displacement of the eye (proptosis), and tissue death. Other forms of disease may infect the lungs, stomach and intestines, and skin. The fatality rate is about 54%.

<span class="mw-page-title-main">Arturo Casadevall</span> Cuban-American scientist

Arturo Casadevall is a Bloomberg Distinguished Professor of Molecular Microbiology & Immunology and Infectious Diseases at the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins School of Medicine, and the Alfred and Jill Sommer Professor and Chair of the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. He is an internationally recognized expert in infectious disease research, with a focus on fungal and bacterial pathogenesis and basic immunology of antibody structure-function. He was elected a member of the National Academy of Sciences in 2022.

<i>Candida auris</i> Species of fungus

Candida auris is a species of fungus that grows as yeast. It is one of the few species of the genus Candida which cause candidiasis in humans. Often, candidiasis is acquired in hospitals by patients with weakened immune systems. C. auris can cause invasive candidiasis (fungemia) in which the bloodstream, the central nervous system, and internal organs are infected. It has attracted widespread attention because of its multiple drug resistance. Treatment is also complicated because it is easily misidentified as other Candida species.

Invasive candidiasis is an infection (candidiasis) that can be caused by various species of Candida yeast. Unlike Candida infections of the mouth and throat or vagina, invasive candidiasis is a serious, progressive, and potentially fatal infection that can affect the blood (fungemia), heart, brain, eyes, bones, and other parts of the body.

<span class="mw-page-title-main">Joseph Heitman</span>

Joseph Heitman is an American physician-scientist focused on research in genetics, microbiology, and infectious diseases. He is the James B. Duke Professor and Chair of the Department of Molecular Genetics and Microbiology at Duke University School of Medicine.

<span class="mw-page-title-main">Chester Wilson Emmons</span> American mycologist (1900–1985)

Chester Wilson Emmons was an American scientist, who researched fungi that cause diseases. He was the first mycologist at the National Institutes of Health (NIH), where for 31 years he served as head of its Medical Mycology Section.

<span class="mw-page-title-main">Tania Sorrell</span> Australian infectious disease physician

Tania Sorrell is an Australian infectious disease physician who is a Professor and Director of the Marie Bashir Institute for Infectious Diseases and Biosecurity at the University of Sydney. She serves as Chair of the National Health and Medical Research Council Research Translation Faculty Steering Group on New and Emerging Health Threats. She is interested in the diagnosis, prevention and treatment of infectious diseases.

References

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Further reading