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.
Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can be fatal if left untreated.
Talaromyces marneffei, formerly called Penicillium marneffei, was identified in 1956. The organism is endemic to southeast Asia where it is an important cause of opportunistic infections in those with HIV/AIDS-related immunodeficiency. Incidence of T. marneffei infections has increased due to a rise in HIV infection rates in the region.
Candida albicans is an opportunistic pathogenic yeast that is a common member of the human gut flora. It can also survive outside the human body. It is detected in the gastrointestinal tract and mouth in 40–60% of healthy adults. It is usually a commensal organism, but it can become pathogenic in immunocompromised individuals under a variety of conditions. It is one of the few species of the genus Candida that cause the human infection candidiasis, which results from an overgrowth of the fungus. Candidiasis is, for example, often observed in HIV-infected patients. C. albicans is the most common fungal species isolated from biofilms either formed on (permanent) implanted medical devices or on human tissue. C. albicans, C. tropicalis, C. parapsilosis, and C. glabrata are together responsible for 50–90% of all cases of candidiasis in humans. A mortality rate of 40% has been reported for patients with systemic candidiasis due to C. albicans. By one estimate, invasive candidiasis contracted in a hospital causes 2,800 to 11,200 deaths yearly in the US. Nevertheless, these numbers may not truly reflect the true extent of damage this organism causes, given new studies indicating that C. albicans can cross the blood–brain barrier in mice.
Paracoccidioides is a genus of fungi in the order Onygenales. Species are known human pathogens producing yeast-like states under pathogenic conditions. They include the causative agents of paracoccidioidomycosis and lobomycosis.
Histoplasma capsulatum is a species of dimorphic fungus. Its sexual form is called Ajellomyces capsulatus. It can cause pulmonary and disseminated histoplasmosis.
Exophiala jeanselmei is a saprotrophic fungus in the family Herpotrichiellaceae. Four varieties have been discovered: Exophiala jeanselmei var. heteromorpha, E. jeanselmei var. lecanii-corni, E. jeanselmei var. jeanselmei, and E. jeanselmei var. castellanii. Other species in the genus Exophiala such as E. dermatitidis and E. spinifera have been reported to have similar annellidic conidiogenesis and may therefore be difficult to differentiate.
Blastomyces dermatitidis is a dimorphic fungus that causes blastomycosis, an invasive and often serious fungal infection found occasionally in humans and other animals. It lives in soil and wet, decaying wood, often in an area close to a waterway such as a lake, river or stream. Indoor growth may also occur, for example, in accumulated debris in damp sheds or shacks. The fungus is endemic to parts of eastern North America, particularly boreal northern Ontario, southeastern Manitoba, Quebec south of the St. Lawrence River, parts of the U.S. Appalachian mountains and interconnected eastern mountain chains, the west bank of Lake Michigan, the state of Wisconsin, and the entire Mississippi Valley including the valleys of some major tributaries such as the Ohio River. In addition, it occurs rarely in Africa both north and south of the Sahara Desert, as well as in the Arabian Peninsula and the Indian subcontinent. Though it has never been directly observed growing in nature, it is thought to grow there as a cottony white mold, similar to the growth seen in artificial culture at 25 °C (77 °F). In an infected human or animal, however, it converts in growth form and becomes a large-celled budding yeast. Blastomycosis is generally readily treatable with systemic antifungal drugs once it is correctly diagnosed; however, delayed diagnosis is very common except in highly endemic areas.
Dimorphic fungi are fungi that can exist in the form of both mold and yeast. This is usually brought about by change in temperature and the fungi are also described as thermally dimorphic fungi. An example is Talaromyces marneffei, a human pathogen that grows as a mold at room temperature, and as a yeast at human body temperature.
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.
A blastoconidium is an asexual holoblastic conidia formed through the blowing out or budding process of a yeast cell, which is a type of asexual reproduction that results in a bud arising from a parent cell. The production of a blastoconidium can occur along a true hyphae, pseudohyphae, or a singular yeast cell. The word "conidia" comes from the Greek word konis and eidos, konis meaning dust and eidos meaning like. The term "bud" comes from the Greek word blastos, which means bud. Yeasts such as Candida albicans and Cryptococcus neoformans produce these budded cells known as blastoconidia.
African histoplasmosis is a fungal infection caused by Histoplasma capsulatumvar. duboisii, or Histoplama duboisii (Hcd). Disease has been most often reported in Uganda, Nigeria, Zaire and Senegal, as Hcd is exclusive to Africa. In human disease it manifests differently than histoplasmosis, most often involving the skin and bones and rarely involving the lungs. Also unlike Hcc, Hcd has been reported to rarely present in those with HIV, likely due to underreporting. However, this along with the differences in Hcc and Hcd have been disputed.
Ajellomyces is a genus of fungi in the division Ascomycota, in the family Ajellomycetaceae. The genus contains two species, which have a widespread distribution, especially in tropical areas. The species Ajellomyces capsulatus is significant to human health as the causative agent of histoplasmosis. This species is more usually referred to as Histoplasma capsulatum, with the designation Ajellomyces capsulatus referring to the ascomycetous perfect stage.
Histoplasma duboisii is a saprotrophic fungus responsible for the invasive infection known as African histoplasmosis. This species is a close relative of Histoplasma capsulatum, the agent of classical histoplasmosis, and the two occur in similar habitats. Histoplasma duboisii is restricted to continental Africa and Madagascar, although scattered reports have arisen from other places usually in individuals with an African travel history. Like, H. capsulatum, H. duboisii is dimorphic – growing as a filamentous fungus at ambient temperature and a yeast at body temperature. It differs morphologically from H. capsulatum by the typical production of a large-celled yeast form. Both agents cause similar forms of disease, although H. duboisii predominantly causes cutaneous and subcutaneous disease in humans and non-human primates. The agent responds to many antifungal drug therapies used to treat serious fungal diseases.
Blastomyces is a genus of fungi in the order Onygenales. Species are known human pathogens and show thermal dimorphism, converting from hyphal states under saprobic conditions to yeast-like states under pathogenic conditions. They are the causative agents of blastomycosis, a systemic mycosis in immunocompromised patients.
Candida tropicalis is a species of yeast in the genus Candida. It is a common pathogen in neutropenic hosts, in whom it may spread through the bloodstream to peripheral organs. For invasive disease, treatments include amphotericin B, echinocandins, or extended-spectrum triazole antifungals.
Emmonsiosis, also known as emergomycosis, is a systemic fungal infection that can affect the lungs, generally always affects the skin and can become widespread. The lesions in the skin look like small red bumps and patches with a dip, ulcer and dead tissue in the centre.
Dectin-2 or C-type lectin domain containing 6A is a protein that in humans is encoded by the CLEC6A gene. Dectin-2 is a member of the C-type lectin/C-type lectin-like domain (CTL/CTLD) superfamily. The encoded protein is a type II transmembrane protein with an extracellular carbohydrate recognition domain. It functions as a pattern recognition receptor recognizing α-mannans and as such plays an important role in innate immune response to fungi. Expression is found on macrophages and dendritic cells. It can also be found at low levels in Langerhans cells and peripheral blood monocytes, where expression levels could be increased upon induction of inflammation.
Emergomyces is a genus of fungi in the order Onygenales. Species are known human pathogens and show thermal dimorphism, converting from hyphal states under saprobic conditions to yeast-like states under pathogenic conditions. They are the causative agents of emergomycosis, a systemic mycosis in immunocompromised patients. The name Emergomyces refers to these newly emerging mycoses, only encountered in the last few decades.
Libero Ajello was an American mycologist. He cofounded and was first president of the International Society of Human and Animal Mycology (ISHAM). He was the head of the Division of Mycotic Diseases at the Communicable Disease Center (CDC), and editor of the ISHAM Journal Medical Mycology for several years. He was one of the first researchers to investigate histoplasmosis and coccidioidomycosis in the United States and made valuable contributions to the comprehensive field of veterinary and human fungal disease diagnosis.
