Thielavia subthermophila | |
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Species: | T. subthermophila |
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Thielavia subthermophila Mouch. (1973) | |
Thielavia subthermophila is a ubiquitous, filamentous [1] fungus that is a member of the phylum Ascomycota and order Sordariales. [2] Known to be found on plants of arid environments, it is an endophyte with thermophilic properties, and possesses dense, pigmented mycelium. [2] [3] [4] Thielavia subthermophila has rarely been identified as a human pathogen, with a small number of clinical cases including ocular and brain infections. [1] [2] For treatment, antifungal drugs such as amphotericin B have been used topically or intravenously, depending upon the condition. [1] [2]
Thielavia subthermophila is a cleistothecial fungus that have a thin peridium, spherical ascoma, and dark-coloured ascospores. [2] [5] It was first described by Jean Mouchacca in 1973 who isolated it from desert soil. [2] To date, there has been confusion in classifying species within the genus Thielavia, as the characteristics of the species are not well-differentiated from perithecial relatives in the genus Chaetomium. [2]
Thielavia subthermophila forms grey colonies with a black reverse, with dark brown, hairy, spherical ascomata that are 90–200 μm in diameter and develop within the mycelial mat. [1] [2] [3] [4] The wall of the ascomata is made of textura epidermoidea or flattened and irregularly outlined cells measuring 6–8 μm in diameter, and is covered with dark, branching hyphae. [1] [2] [3] [4] Aleuriospores and chlamydospores are light brown, single-celled, 5–7 × 3–5 μm in diameter, have a truncate base, and grow terminally and laterally on short branches or hyphae. [1] [3] [4] Thielavia subthermophila has asci measuring 20–30 × 15–22.5 μm in diameter, each containing 8 spores. [6] It has single-celled, dark olive to black, fusiform or elliptical ascospores measuring 14–20 × 8–10 μm in diameter with a subapical germ pore measuring 1–1.5 μm in diameter. [1] [2] [4] [5] [6] Compared to other species within the genus Thielavia such as Thielavia arenaria and Thielavia microspora, it is known to produce large ascospores. [6] A felt-like aerial mycelium is characteristic of T. subthermophila, consisting of septate, branched, and hyaline or dark olive hyphae and measuring 1–3 μm. [1] [6]
Thielavia subthermophila shows optimal growth and survival up to 36–45 °C (97–113 °F), as determined by its thermotolerant properties, and possesses light-protection structures. [2] [3] [4] [6] The asexual reproductive form of Thielavia subthermophila is associated with production of pale yellowish brown, smooth aleurioconidia measuring 3–4 × 2.5–3 μm in diameter, with no conidiophores present. [4] [5] [6] Sexual reproduction is associated with abundant production of cleistothecia that are brownish black to black, scattered, and 120–180 μm in diameter, covered by dark olive hairs. [6]
Thielavia subthermophila has been isolated from a wide range of environments, such as soil, camel hair, and desert vegetation. [1] In addition, it has been found in dried Hibiscus flower, Brazilian pepper seeds, and species of herbal plants such as "Plantaginis herba", "Plantaginis semen", and Abies webbiana. [1] [6] Notably, T. subthermophila has been isolated as an endophyte of Hypericum perforatum, otherwise known as St. John's wort. [3]
Emodin is a fungal metabolite that has been isolated from Thielavia subthermophila, which inhibits the expression of cytokines, chemokines, and inflammatory modulators in vitro. [3] [7] Hypericin is a fungal metabolite that has also been isolated from Thielavia subthermophila, that initiates high cytotoxicity when excited by irradiation with visible light. [3] Thielavia subthermophila isolated from the stems of Hypercium perforatum has been recognized to undergo mechanisms of emodin and hypericin biosynthesis. [3]
As with other Thielavia species, Thielavia subthermophila has rarely been identified to be involved in human fungal infections. [2]
Thielavia subthermophila has been recognized to cause ocular infections in humans, as it has been isolated from corneal scrapings of an infected patient, characterized by lesions with central ulceration and ill-defined margins. [1]
Thielavia subthermophila has been known to cause fatal brain infections in humans, with the first case reported in an immunocompetent, Indian male. [2] In the brain, its growth is known to be associated with fungal granulomas centered around blood vessels and branched fungal hyphae in the parenchyma. [2] Cerebral phaeohyphomycosis due to Thielavia subthermophila is characterized by the production of pus and necrotic tissue in the brain. [2] Symptoms of cerebral phaeohyphomycosis include foaming at the mouth, fever, seizures, involuntary urination, and uncontrolled movement of eyes and limbs. [2]
To treat ocular infections, antifungal medication such as oral voriconazole and amphotericin B eyedrops can be administered to the patient. [1] Fortified tobramycin, fortified cefazolin, fluorometholone, and scopolamine eyedrops can also be administered if necessary, depending on the symptoms. [1] In addition, corneal abrasion can be performed on the patient to facilitate penetration of the antifungal medication. [1] Amphotericin B therapy, surgical removal of infected tissue, and immune enhancement can be used to treat cerebral phaeohyphomycosis by Thielavia subthermophila, although despite treatment, is associated with high mortality. [2] Currently, there is no accepted standard treatment for brain infections by T. subthermophila. [2]
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.
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.
Acrophialophora fusispora is a poorly studied ascomycete fungus found in soil, air and various plants. A. fusispora is morphologically similar to the genera Paecilomyces and Masonia, but differ in the presence of pigmented conidiophores, verticillate phialides, and frequent sympodial proliferation. Moreover, A. fusispora is distinguished by its pigmented spindle-shaped conidia, covered with spiral bands. The fungus is naturally found in soils of tropical to temperate regions. The fungus has been identified as a plant and animal pathogen, and has recently been recognized as an emerging opportunistic human pathogen. A. fusispora infection in human is rare and has few documented clinical cases, but due to the rarity of the fungus and potential misidentification, the infections may be underdiagnosed. Clinical cases of A. fusispora include cases of keratitis, pulmonary colonization and infection, and cerebral infections. The fungus also has two documented cases of infection in dogs.
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.
Pseudallescheria boydii is a species of fungus classified in the Ascomycota. It is associated with some forms of eumycetoma/maduromycosis and is the causative agent of pseudallescheriasis. Typically found in stagnant and polluted water, it has been implicated in the infection of immunocompromised and near-drowned pneumonia patients. Treatment of infections with P. boydii is complicated by resistance to many of the standard antifungal agents normally used to treat infections by filamentous fungi.
Exophiala dermatitidis is a thermophilic black yeast, and a member of the Herpotrichiellaceae. While the species is only found at low abundance in nature, metabolically active strains are commonly isolated in saunas, steam baths, and dish washers. Exophiala dermatitidis only rarely causes infection in humans, however cases have been reported around the world. In East Asia, the species has caused lethal brain infections in young and otherwise healthy individuals. The fungus has been known to cause cutaneous and subcutaneous phaeohyphomycosis, and as a lung colonist in people with cystic fibrosis in Europe. In 2002, an outbreak of systemic E. dermatitidis infection occurred in women who had received contaminated steroid injections at North Carolina hospitals.
Ochroconis gallopava, also called Dactylaria gallopava or Dactylaria constricta var. gallopava, is a member of genus Dactylaria. Ochroconis gallopava is a thermotolerant, darkly pigmented fungus that causes various infections in fowls, turkeys, poults, and immunocompromised humans first reported in 1986. Since then, the fungus has been increasingly reported as an agent of human disease especially in recipients of solid organ transplants. Ochroconis gallopava infection has a long onset and can involve a variety of body sites. Treatment of infection often involves a combination of antifungal drug therapy and surgical excision.
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Coniochaeta hoffmannii, also known as Lecythophora hoffmannii, is an ascomycete fungus that grows commonly in soil. It has also been categorized as a soft-rot fungus capable of bringing the surface layer of timber into a state of decay, even when safeguarded with preservatives. Additionally, it has pathogenic properties, although it causes serious infection only in rare cases. A plant pathogen lacking a known sexual state, C. hoffmannii has been classified as a "dematiaceous fungus" despite its contradictory lack of pigmentation; both in vivo and in vitro, there is no correlation between its appearance and its classification.
Phaeohyphomycosis is a diverse group of fungal infections, caused by dematiaceous fungi whose morphologic characteristics in tissue include hyphae, yeast-like cells, or a combination of these. It can be associated with an array of melanistic filamentous fungi including Alternaria species, Exophiala jeanselmei, and Rhinocladiella mackenziei.
Phialemonium curvatum is a pathogenic fungus in the phylum Ascomycota. The genus was created to accommodate taxa intermediate to Acremonium and Phialophora. This genus is characterized by its abundance of adelophialides and few discrete phialides with no signs of collarettes. Specifically, P. curvatum is characterized by its grayish white colonies and its allantoid conidia. Phialemonium curvatum is typically found in a variety of environments including air, soil, industrial water and sewage. Furthermore, P. curvatum affects mainly immunocompromised and is rarely seen in immunocompetent people. The species has been known to cause peritonitis, endocarditis, endovascular infections, osteomyelitis as well as cutaneous infections of wounds and burns.
Chaetomium globosum is a well-known mesophilic member of the mold family Chaetomiaceae. It is a saprophytic fungus that primarily resides on plants, soil, straw, and dung. Endophytic C. globosum assists in cellulose decomposition of plant cells. They are found in habitats ranging from forest plants to mountain soils across various biomes. C. globosum colonies can also be found indoors and on wooden products.
Chaetomium atrobrunneum is a darkly pigmented mould affiliated with the fungal division, Ascomycota. This species is predominantly saprotrophic, although it has been known to infect animals including humans, showing a proclivity for the tissues of the central nervous system. Chaetomium atrobrunneum was described in 1949 from a mouldy military mattress cover obtained from the island of Guadalcanal.
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Cladophialophora arxii is a black yeast shaped dematiaceous fungus that is able to cause serious phaeohyphomycotic infections. C. arxii was first discovered in 1995 in Germany from a 22-year-old female patient suffering multiple granulomatous tracheal tumours. It is a clinical strain that is typically found in humans and is also capable of acting as an opportunistic fungus of other vertebrates Human cases caused by C. arxii have been reported from all parts of the world such as Germany and Australia.
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