U.S. Micro-Solutions, Inc. Fungal Library
Fungi are eukaryotic organisms which include unicellular yeasts, multicellular molds, and macroscopic varieties such as mushrooms. The colony of mold consists of long filaments called hyphae through which dissolved organic matter is absorbed. When environmental conditions are suitable, the hyphae grow, intertwine, and form a mass called a mycelium.
The portion of mycelium concerned with obtaining nutrients is called the vegetative mycelium; the portion concerned with reproduction is called reproductive or aerial mycelium. The aerial mycelium as the name implies, projects above the surface of the medium on which the fungus is growing and often bears the reproductive spores. Spores are of key importance in the fungal identification process.
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Absidia (see under Mycocladus)
The genus Acremonium (formerly called Cephalosporium) are widespread occurring in soil and decaying plant material. The genus contains over 100 species. These fungi, being ubiquitous in the environment, are known to colonize the surfaces of many materials indoors as well as the HVAC systems of hospitals, schools, and commercial buildings. Acremoniumspecies generally require moist conditions to amplify (grow) indoors. Identification to the species level, however, is difficult.
Disease Associations: Several species are documented to cause onychomycosis (nail infections), corneal ulcers, and eumycotic mycetoma. Cases of meningitis and endocarditis have been reported particularly in the immunocompromised host. Infections of artificial implants are occasionally reported.
Alternaria species are one of the most abundant fungi in the atmosphere, they are isolated from various habitats; plant pathogens (common tomato pathogen) or saprobes, in the soil, on foodstuffs, and textiles. In most parts of the world, Alternaria may be identified from atmospheric sampling year-round, although highest overall concentrations often occur in summer and early fall in temperate areas.
Disease Associations: Published reports suggest that a concentration >100 conidia/m³ of air may induce allergic symptoms. Cases of onychomycosis (nail infections), sinusitis, ulcerated cutaneous infections and keratitis have been reported. Rare cases of deep-seated (invasive) disease do occur in the immunocompromised host.
Arthrographis species are a cosmopolitan mould isolated from soil and decaying vegetation. Two species of Arthrographis are most commonly isolated in the laboratory: A. cuboidea and A. kalrae. Arthrographis kalrae has been isolated from skin, nails, and respiratory sites, but has not been established as an etiologic agent of disease. Both species are considered to be allergenic. Toxic related disease has not been associated with this mould.
The genus Aspergillus is widely distributed in the environment, being identified in soil, on plants and decaying vegetation, in dust, on stored food, fruits, vegetables, feed products, wood chips, cotton, and in the air. The genus contains approximately 200 species and about 20 species of Aspergillus have been recognized as opportunistic pathogens. The most common of the opportunistic pathogens in this group is Aspergillus fumigatus.
A. fumigatus may be recovered from the indoor environment and is common in trash, house dust, and compost.
A. fumigatus has worldwide distribution and grows over a wide range of temperatures. It is commonly recovered outdoors in compost piles, wood chips, soil, plants, seeds, and cotton.
A. fumigatus is thermotolerant and is able to grow over a wide range of temperatures from below 20° up to 50° C. It flourishes in mild to warm soils and vegetable matter decomposing in warm environments, such as self-heating hay and composts.
A. flavus grows on mouldy corn, peanuts, and other agricultural products. It can be found in soil, foods, and dairy products. Some strains produce a group of mycotoxins called aflatoxins.
A. glaucus has a worldwide distribution and can be isolated from soils and a wide range of saprophytic habitats. It is xerophilic (dry loving) and is especially common on dry or concentrated substances such as dried foods and leather.
A. nidulans is widespread and primarily found in mild to warm soils and on slowly decaying plant material. It also can be found on potatoes, grain, citrus, and stored seeds of oats, wheat, corn, rice, and cotton.
Aspergillus niger is commonly found in the environment on textiles, in soils, grains, fruits, and vegetables. This species is considered common to indoor environments and usually displays a very musty odor.
A. ochraceus is a common fungus reported in soils, desert soils, plant rhizospheres, stored seeds, a wide range of foods, and indoor environments.
A. sclerotiorum is a slow growing pale yellow fungus that is predominantly a soil fungus isolated most frequently from subtropical zones. It has been reported in desert soils and in the 36-45 degree latitude range.
A. terreus has world-wide distribution in tropical and subtropical areas. It is common in stored crops.
A. ustus is one of the more ubiquitous soil-borne Aspergillus species with its main occurrences in the tropics and subtropics. It is relatively uncommon in habitats other than soil and on seeds, but has been isolated from indoor environments and food (especially grains and peanuts).
A. sydowii has a world-wide distribution and can often be isolated from soil, cotton, beans, fabrics, leather, and paper. The fungus can commonly be isolated from the indoor environment.
A. versicolor is a widely distributed fungus being detected in very cold regions, unlike most other species of aspergilli which prefer warmer regions. It may be commonly found in soil, hay, cotton, dairy products, dried cereals, nuts, and especially spices. The fungus is commonly recovered from buildings with humidity and ventilation problems.
Disease Associations: Members of this genus cause a group of diseases known as aspergillosis.Aspergillus spp. are well-known to elicit three different clinical settings; namely, (1) allergic states; (2) toxicosis; (3) opportunistic infection. The most predominant form of aspergillosis is pulmonary and over 95% of all infections are caused by three species: (A. fumigatus, A. flavus, A. niger).
Aspergillosis may also be caused by other species, namely, A. glaucus, A. nidulans, A. terreus, A. versicolor, A. clavatus, and A. ustus. Aspergillus fumigatus is the second most common fungus in opportunistic mycoses following Candida albicans in the hospitalized patient.
Aspergillus fumigatus is the most commonly encountered pathogen in the immunocompromised patient and is especially active as an allergic and invasive organism. A. fumigatus is a common cause of allergic bronchopulmonary aspergillosis and is especially noted in the atopic individual. Aspergillosis is currently the most common fungal infection of the paranasal sinuses.
Some strains of Aspergillus flavus produce a group of mycotoxins called aflatoxins. Aflatoxins are known animal carcinogens and there is limited evidence that this toxin may be a human carcinogen. It has been reported to cause occupational disease by inhalation. A. flavus has been associated with lung and disseminated aspergillosis. This fungus has also been reported as a cause of corneal, otomycosis, and naso-orbital infections.
Aspergillus niger is a less common cause of invasive aspergillosis. It has been reported to cause skin and pulmonary disease. It is also a common cause of fungal otomycosis (ear infections).
Aureobasidium pullulans is a cosmopolitan fungus with its main habitat on the aerial parts of plants. Frequently isolated indoors in areas of free water such as condensate pans, flooded carpet, and other moist sites where water intrusion has occurred. It is a yeast-like fungus that generally becomes airborne through mechanical disruption of contaminated materials or by aspiration of contaminated water.
Disease Associations: Aureobasidium pullulans does not cause primary human disease; however, high airborne levels have been associated with allergic reactions probably due to respiratory irritation. This fungus has been associated with human cases of keratitis, peritonitis, pulmonary disease, and invasive infection in an AIDS patient. No toxic diseases have been reported to date.
This class of organisms comprises one of the major taxon of true fungi. Basidiomycetes produce sexual spores called basidiospores at tips of tiny outgrowths from special cells called basidia. Many basidiomycetes also produce asexual spores called conidia, but in most cases these are not as conspicuous or numerous as in the Ascomycetes, and they do not seem to constitute a significant part of the air spora. These fungi include the mushrooms, bracket fungi, puff balls, and other macrofungi. Several genera (Lenzites, Merulius, Odontia, and Poria spp.) are known to cause dry rot. These decay fungi grow on and in wood and destroy the wood substances as they grow. Ingestion of a poisonous mushroom causes a disease entity known as mycotoxicosis. Some basidiospores can be identified by spore morphology on Air-O-Cell slides, but few if any grow on common laboratory agar media. Many basidiospores are reported to be allergenic.
This zygomycete has been isolated from decaying plants, soil, and from the fecal material of frogs, reptiles, fish, and bats. Its relationship to human occupied spaces suggests a common presence in the indoor environment, especially in tropical countries. This fungus rarely causes disease and no toxic effects have been documented to date. It has been reported in subcutaneous zygomycosis which involves predominantly the trunk and extremities, most often in children in tropical countries. This fungus rarely causes the disease entity rhinocerebral zygomycosis, typical of the other Mucorales (e.g., Rhizopus spp.).
Beauveria species are ubiquitous in soil and plant debris with various species being parasites of insects. Beauveria bassiana is recognized as the etiologic agent of the devastating muscardine disease of silkworms. Beauveria species have been reported to cause mycotic keratitis and occasional pulmonary infection. These fungi should be considered allergenic, but no toxic diseases have been documented to date.
Bipolaris species are dematiaceous (pigmented) filamentous fungi that are widespread in nature and are most frequently associated with grasses, plant material, decaying food, and soil. Nearly all species of this genus are pathogenic to grasses, while some are common saprobes on dead plant material and in soil. Older obsolete names include Drechslera andHelminthosporium.
Disease Associations: Bipolaris species are one of the causative agents of phaeohyphomycosis, particularly fungal sinusitis. The clinical spectrum is quite diverse, including allergic and chronic invasive sinusitis, keratitis, endophthalmitis, endocarditis, osteomyelitis, and fungemia as well as cutaneous and pulmonary infections and allergic bronchopulmonary disease. Bipolaris spicifera is the most commonly implicated Bipolaris species in human disease.
Blastoschizomyces capitatus (formerly called Trichosporon capitatus) may be isolated from environmental sources such as soil, beach sand, and as normal flora of the skin, respiratory, and digestive tracts of humans. Although found in the environment, the largest study of the epidemiology of infection with this yeast-like fungus failed to reveal a common environmental exposure.
Disease Associations: Invasive disease has been documented in immuno-compromised patients. With the increasing populations of immunocompromised patients, infections due to this and other yeast species that were previously considered unusual are likely to become increasingly common. No toxic diseases have been documented to date.
Botrytis species are parasitic on plants, vegetables, and soft fruits and have also been found in soil. They are often recorded from regions of humid climate, both temperate and tropical. They are reported to be allergenic, but no cases of infections have been documented in humans.
Botryotrichum species are occasionally found on dead herbaceous plants and frequently isolated from air, canvas, cellophane, dung, paper, and soil.
Candida species have been isolated from a variety of environmental sources. Several Candida species, most notably C. albicans are ubiquitous human colonizers of the skin and mucous membranes in humans. C. albicans has also been isolated from leaves, flowers, water, and soil, but the yeast generally does not become airborne. Other species of Candida have been isolated from mammals, birds, air samples, vegetation, juices, dairy products, grains, and insects.
Disease Associations: Seven species in the genus Candida are well-known opportunistic human pathogens (C. albicans, C. glabrata, C. guilliermondii, C. krusei, C. lusitaniae, C. parapsilosis, C. tropicalis) and many others have been described as pathogens in individual case reports. Diseases caused by Candida species cover a diverse range of pathologic effects and are associated with many numerous underlying host factors that predispose persons to infections with Candida species. The most common infections include skin, nails, oral disease (thrush), and the genital tract of females. Candida infections of deep tissue are usually the result of hematogenous spread of the yeast from an endogenous site. Widely disseminated disease, usually with a fatal outcome if untreated, can occur in the immunocompromised patient. No toxic diseases have been reported to date.
The fungus produces long, cylindrical several celled hyaline conidia. The mould is parasitic on many higher plants, commonly causing leaf spots. Of the 500 species of Cercospora occurring in North America, only a few species have their perfect stages (sexual/teleomorph) known and all belonging to the genus Mycosphaerella in the class Ascomycetes.
Chaetomium species are found in soil, air, and plant debris. Indoors they can be found on a variety of substrates containing cellulose including paper, textiles, plaster, and water damaged paper in sheetrock. Chaetomium species are ascomycetous fungi producing ascocarps called perithecia (contains sexual spores called ascospores). Chaetomium species may be recognized on spore trap slides by their characteristic ascospores.
Disease Associations: Chaetomium atrobrunneum is a thermophilic and neutrotropic fungus which makes this species a potentially agressive fungal pathogen. While considered to be allergenic, no toxic diseases have been reported. Chaetomium globosum is considered to be allergenic, but no toxic diseases have been documented to date. This fungus is the most common and widely distributed species of Chaetomium. This species is documented as an agent of onychomycosis (nail infection), peritonitis, and cutaneous lesions.Chaetomium strumarium is a common soil mould in warm areas on plant debris. It has been documented in fatal brain infections; however no toxic diseases have been documented to date.
Chrysosporium is a genus of predominantly saprophytic moulds, and many species are isolated in soils and associated with keratinous substrates such as shed hair or skin scales, fur, feathers, hooves, etc. Chrysosporiumspecies usually have single-celled (rarely one- or two-septate) conidia; whereas species of dermatophytes (e.g., Trichophyton or Microsporum spp.) have or are capable of producing multi-celled conidia known as macroconidia.
Disease Associations: A few species of Chrysosporium are closely related biologically to dermatophytes, even though they are normally nonpathogenic. Eight species occasionally occurring on humans have been identified. Chrysosporiumspecies have been reported to cause disseminated disease and invasive sinusitis among immunocompromised persons. Some geophilic species have been repeatedly isolated from onychomycosis (nails) and superficial infections. Toxic diseases have not been reported to date.
Cladophialophora species are dematiaceous (dark pigmentation) fungi widely distributed in the soil and on plant debris. Unlike Cladosporium species,Cladophialophora species normally produce small conidia in long chains without shield cells or attachment scars.
Disease Associations: Cladophialophora bantiana is the most common agent involved in cerebral phaeohyphomycosis. Because this disease usually infects immunocompetent individuals presumably by way of the respiratory tract, this mould should be handled with care in the laboratory. C. carrionii is usually associated with chromoblastomycosis, which is generally restricted to subtropical and tropical areas of the world. Most persons have long-term soil exposure with repeated trauma and tissue injuries to the feet and legs. C. boppii has been associated with skin lesions and may be a possible cause of chromblastomycosis. Toxic diseases have not been reported to date.
Cladosporium species are ubiquitous with worldwide distribution and are the most common mould on dead organic matter and in the air. In most parts of the world Cladosporium species are the most abundant genus isolated from air sampling. The highest concentrations outdoors of Cladosporium species occur in summer and early fall in temperate areas and reduces in the winter months. Cladosporium cladosporioides is the most common species on dead organic matter and in the air. Cladosporium species are common in indoor environments and often isolated from the surface of fiberglass duct liners around return and supply ducts, shower walls & curtains, and basement walls. They are usually found indoors in numbers less than outdoor numbers.
Cladosporium cladosporioides is the most common species of its genus both on plant materials and in soil. The conidia are very commonly air-borne and their frequency usually peaks in temperate climates in June-July and September-October. In the temperate zone, this species has been isolated frequently from various forests as well as from grassland, garden, and arable soils, dunes, salt marshes and saline beaches. Its presence has been demonstrated in clean and highly polluted streams, lake and marine habitats, fields treated with sewage sludge, activated sludge, and compost beds. It has also been isolated as a ubiquitous contaminant from a wide variety of room temperature and refrigerated foods.
Cladosporium herbarum is an extremely ubiquitous organism making up a large part of the air spora in temperate zones. Together with C. cladosporioides, this is the most common Cladosporium species on dead organic matter and, in general, one of the most common fungi on dying and dead plant material, in particular leaves and stems of the most varied plant species including ferns, mosses, aquatic, and desert plants. The dry conidia are easily carried through the air and have been transported over oceans. In numerous investigations of the spore content air, Cladosporium has been the dominant genus; with C. herbarum the commonest species.
Disease Associations: Although Cladosporium spp. is the most common of the fungi worldwide, it only rarely acts as an opportunistic pathogen in humans. C. cladosporioides, C. sphaerospermum. C. elatum, and C. oxysporum have been reported as rare agents of phaeohyphomycosis. Cladosporium herbarum has been reported in cutaneous infection and keratitis. Studies have confirmed the importance of allergens of Cladosporium spp. as a cause of asthma, hay fever, and hypersensitivity pneumonitis (HP). Toxic effects have been reported in animals but toxic disease has not been reported to date in humans.
Coelomycetes are fungi which produce conidia in fruit bodies (conidiomata). In such fruit bodies, the propagules are mitotic, non-sexual. Examples of Coelomycetes are Colletotrichum, Pyrenochaeta, and Phoma species. This is in contrast to Ascomycetes which come from a sexual process with fruiting bodies referred to as ascomata which produce sexual spores called ascospores. Examples are Chaetomium, Microascus, and Emericella.
As a member of the class Zygomycetes, Conidiobolus species are found in decaying wood, plant debris, on insects, and in the G-I tract of lizards and toads in tropical areas. There are seasonal variations in the detection ofConidiobolus coronatus from soil with the greatest yield in September and October. C. coronatus most commonly causes a granulomatous disease involving nasal mucosa and subcutaneous maxillofacial tissues. These infections are rare, with only a few cases reported in the United States.
The genus Cryptococcus includes oval to round yeasts that reproduce by multilateral budding and are anamorphs of the jelly fungi and smuts of the Basidiomycetes. Of the more than 34 species of the genus, Cryptococcus neoformans is the only one considered pathogenic to humans and causes the disease cryptococcosis. Originally three varieties have been recognized, namely var. neoformans, var. grubii and var. gatti, on the basis of their different life cycles, physiology, ecology, and genetics. C. neoformans var.gatti (now called C. gatti) is detected in tropical and subtropical climates associated with Eucalyptus trees; but recently has been isolated from soil in the Pacific Northwest (2004) and Vancouver, Canada (1999), whereas C. neoformans is found worldwide and is associated with pigeon droppings and soil contaminated with avian excreta. According to recent studies, the environmental habitat of C. neoformansappears to be related to trees and plant material as it is for C. gatti. Pigeon droppings only continue the propagation of the fungus, providing an enriched media for growth and dispersion. In fresh or wet pigeon droppings, C. neoformans yeast cells are somewhat inhibited, which in contrast are highly resistant in dry excreta. Avian excreta are likely to be positive for C. neoformans in sheltered environmental sites than in those exposed to sunlight because of the high susceptibility of this fungus to UV light.
Disease Associations: C. neoformans causes infections in animals and humans throughout the world. The fungus may infect normally healthy persons, but usually causes disease in the immunocompromised host and presents as a pulmonary and/or central nervous system infection. C. neoformans commonly occurs in the environment of urban areas, and even though human exposure to the fungus appears to be a common event, cryptococcosis remains a sporadic disease. Human to human and animal to human natural transmission has never been reported and nosocomial infections have not been described. Normal hosts are rarely reported to be infected with C. neoformans var. neoformans. However, normal or immunocompetent persons may develop cryptococcosis due to Cryptococcus gatti in those countries where this variety is endemic. Recent reports in the literature have confirmed cases of cryptococcosis caused by Cryptococcus gatti primarily in otherwise healthy persons in the Pacific Northwest (Oregon and Washington). The most commonly encountered predisposing factor for development of cryptococcosis is AIDS. Less commonly, cancer patients receiving chemotherapeutics or long-term corticosteroid treatment, and organ transplant recipients may also develop cryptococcosis.
Cunninghamella species are zygomycete fungi with a wide distribution in decaying vegetation and animal matter, in the soil, and recovered from foodstuffs and fruit. These fungi have been mainly found in Mediterranean or subtropical climatic zones. These fungi are thermotolerant and are able to grow at temperatures above 37°C. C. bertholletiae is known as an occasional agent of zygomycosis causing pneumonia in immunocompromised children, disseminated disease in renal and liver transplant recipients, and infections in AIDS patients.
Curvularia species are known to have a wide distribution, mostly occurring on dead plant material. Curvularia species are particularly common as a saprophyte or weak pathogen causing leaf spots, seedling blight, and seed germination failure. These fungi produce darkly pigmented (dematiaceous) brown to black hairy colonies on an agar plate. The mould is recognized microscopically by uniquely shaped multiseptate conidia that are usually curved as the result of an enlarged central cell, which is also darker than the other surrounding cells.
Disease Associations: Curvularia species are among the important causes of fungal keratitis, sinusitis, and cutaneous infections by traumatic implantation. They have been reported as agents of phaeohyphomycosis causing mycetoma and subcutaneous and systemic disease, with most infections occurring in the immunocompromised host.
This dematiaceous mould has worldwide distribution occurring on a variety of organic materials such as dead wood, herbaceous stems, dung, and from the soil. The genus is the synnematal counterpart of Scopulariopsis. In most species synnematal development is good on most fungal media. In older cultures, simple Scopulariopsis-like conidiophores may predominate.The fungus has not been documented as an etiologic agent of disease.
Drechslera species are cosmopolitan fungus isolated from soil and plant material, particularly grasses. Some species are plant pathogens. Microscopically they may be confused with Bipolaris spp. or Exserohilum spp. Although D. biseptata has been shown to have pathogenic potential, most reports of disease caused by Drechslera species represent either misidentification or fungi that have since been reclassified as Bipolaris orExserohilum species (Anaissie, McGinnis, & Pfaller, Clinical Mycology, 2003).
Engyodontium album can be commonly detected in moist waste material and frequently isolated from paper, jute, linen, and painted walls. This fungus must be microscopically distinguished from Beauveria and Tritirachium spp. The mould has been reported to cause keratitis, brain abscess, and endocarditis.
Epicoccum species are dematiaceous mould that has widespread distribution being isolated from air, animals, foodstuffs, and textiles. They are common early secondary invaders of numerous plants causing leaf spots. Epicoccumspecies are allergenic fungus, but not documented as an etiologic agent in human or animal disease.
Exophiala species are cosmopolitan fungi being isolated from decaying wood, soil, and surfaces in contact with cool, fresh water. Exophiala species are the main genus of black yeasts. Most species are olivaceous to black and initially yeast-like, later becoming velvety with the production of aerial hyphae. Some species of Exophiala are entirely yeast-like on culture in the laboratory. The pleomorphic nature of Exophiala species and their intraspecies variations make identification and differentiation difficult. Phaeoannellomyces werneckiiis another current name for Exophiala werneckii.
Disease Associations: Only a small number of the described Exophiala species have been reported to cause human infections. E. jeanselmei is the most common agent of phaeohyphomycotic cysts and subcutaneous lesions and the species also causes mycetoma and chromoblastomycosis. Some of the other species of Exophiala are known to be agents of phaeohyphomycosis.
Exserohilum species are cosmopolitan dematiaceous fungi commonly found as a plant pathogen mainly on grasses, many other plants, and in the soil.Exserohilum species are distinguished from Bipolaris and Drechslera by their conidia with a protuberant hilum. Human mycoses usually involve cases of sinusitis, eventually with cerebral involvement. Some cases of subcutaneous or deep phaeohyphomycosis have been reported in humans and animals.
The genus Fusarium is widespread as a common soil saprophyte and is an important plant pathogen. Some species produce toxins in grains or stored animal feed. On culture media, this rapidly growing fungus appears in pink, yellow, red, or purple shades. Fusarium species are usually identified by their characteristic multicellular sickle-shaped macroconidia, but identification may be difficult with some species.
Disease Associations: Fusarium species cause a wide spectrum of human disease, including mycotoxicosis and infections which may be superficial, invasive, or disseminated. Fusarium species frequently occur as agents of various kinds of hyalohyphomycosis after traumatic inoculation. Fusarium may cause localized infections of the cornea, skin, and nails in the immunocompetent host. In severely immunocompromised patients, Fusarium has recently emerged as a significant cause of morbidity and mortality and is the second most common pathogenic mould (after Aspergillus) in high risk patients with hematologic cancer and in recipients of solid organ transplantation or allogeneic bone marrow transplantation (BMT).
Fusicladium is a cosmopolitan dematiaceous (dark pigmentation) hyphomycete fungus belonging to the Class: Ascomycetes. The conidia are solitary or occasionally in short chains (some species resemble Cladosporiumin their morphology), often 1-septate pale to mid olive or olivaceous brown. The conidial stage (asexual form of the fungus) can be very destructive (parasitic) to leaves, shoots, buds, flowers and fruit of higher plants (e.g. apple, pear) causing scab formation. It is not known to cause disease in humans.
Geotrichum species are ubiquitous fungus with worldwide distribution occurring in soil, air, water, sewage, various plants, cereals, dairy products, fruits, and is present as normal flora of the upper respiratory tract of humans.Geotrichosis is generally an infection of the bronchi, lungs, and mucosa caused by the yeast-like fungus, Geotrichum candidum. In the mouth it can produce thrushlike lesions.
Hormonema dematioides is a black yeast-like fungus recognized as an opportunistic pathogen of conifers and possibly other plants. It is often found in moist indoor environments. It must be distinguished from the black yeast-like fungus, Aureobasidium pullulans. This fungus has been reported as a rare cause of cutaneous phaeohyphomycosis and fungal peritonitis.
Lecythophora species are yeast-like fungi that have widespread distribution occurring in decaying vegetation and in the soil. They are associated with moist environments and have been isolated from rotten wood and foodstuffs.L. hoffmannii has been reported to cause subcutaneous abscess and keratitis. Fungal sinusitis has been described in AIDS patients. L. mutabilishas been reported to cause peritonitis, endocarditis, and keratitis.
Leptosphaeria is a dematiaceous (darkly pigmented hphae) mould frequently detected in soil. Leptosphaeria coniothyrium has a known anamorphic (asexual) growth phase included in the genus Coniothyrium. Leptosphaeria is an occasional cause of human mycetoma and phaeohyphomycosis.
Memnoniella species have worldwide distribution and have been isolated from soil, paper, wallpaper, textiles, and decaying plant material. They are associated with moist environments and are indicative of wet, damp, or water related conditions. They are known to produce toxic metabolites similar to that produced by Stachybotrys chartarum.
Mucor species, members of the order Mucorales, have worldwide distribution and are found in decaying vegetables, foods, and animal excreta. Mucorspecies are rapidly growing fungi on laboratory agar media and are distinguished from Rhizopus species by their lack of formation of rhizoids.
Disease Associations: Zygomycoses (which includes Mycocladus, Mucor, Rhizopus, etc.) are rare in healthy individuals, unless trauma has provided a portal of entry into the body for the fungus. Mucor species are rare causes of disseminated disease, but the fungus has been recovered from cutaneous lesions, endocarditis, and arthritis. Rhinocerebral disease has also been described with Mucor species.
Mycocladus (formerly Absidia) corymbifera
Mycocladus corymbifera in the Division: Zygomycota with a wide geographic distribution in which it uses a variety of substrates as nutrient sources. These moulds (Mycocladus, Basidiobolus, Conidiobolus, Mucor, andRhizopus) are ubiquitous and thermo-tolerant and can be isolated in large numbers from soil or decomposing organic material. Members of the orderMucorales (Apophysomyces, Mycocladus, Mucor, Rhizomucor, andRhizopus) are found in decaying vegetables, foodstuffs, fruit, soil, and animal excreta. Their spores can often be found in the outdoor air. Mycocladus does occasionally cause human disease.
Disease Associations: Zygomycoses are rare in healthy individuals, unless traumatic implantation (e.g., wounds) has allowed a portal of entry for the fungus. However, most infections follow inhalation of spores that have been released into the air, and the lungs and nasal sinuses are common sites of infection. Major risk factors include ketoacidosis, lymphoma, leukemia, neutropenia, corticosteroids, or other long-term immunosuppressive therapies.
Myxomycetes are a class of viscous or mucilaginous fungi, also called slime moulds. These organisms have affinities to both animals and fungi. The plasmodial (amoeboid) feeding stage shows animal-like characteristics. They have no cell wall and actively engulf organic matter and bacteria in the environment. The reproductive stage, however, places the slime moulds with fungi, since spores are produced within fruiting bodies. These spores are well adapted for wind dispersal and have been identified in air samples. However, it is difficult to differentiate Myxomycetes from the smuts and the genusPericonia on spore trap preparations. They have been reported to be allergenic to sensitized persons.
Nigrospora species have a widespread distribution in decaying plant material, the soil, and air. Nigrospora species are distinguished from Humicola species by very black, opaque, conidia borne on hyaline, inflated conidiophores. They have not been documented as an etiologic agent of disease, but has been reported from a lesion in a leukemic patient and as a probable cause of keratitis.
The mould has worldwide distribution occurring on dead branches or fallen trunks and logs. It is one of a very few genera containing both dematiaceous (dark) and moniliaceous (clear-hyaline) species. Nodulisporium is an anamorph (asexual form) but is associated in nature with many ascomycete species of the Xylariaceae family especially Hypoxylon. Known as an etiologic agent of allergic fungal sinusitis, but recently has been isolated from a human case of cerebral phaeohyphohomycosis.
Most species of Paecilomyces are commonly isolated worldwide from soil and decaying plant material and are often implicated in decay of food products and cosmetics. Some species are able to tolerate high temperatures; thus are inhabitants of compost piles. P. variotii is able to produce significant mycotoxins such as patulin and viriditoxin.
Disease Associations: The two most commonly isolated species of Paecilomyces: P. lilacinus andP. variotii are rarely pathogenic to humans. However, P. lilacinus is being reported with increasing frequency and is now considered an emerging fungal pathogen. In immunocompetent persons, Paecilomyces species have been implicated as etiologic agents of keratitis associated with corneal implants, endophthalmitis, endocarditis following valve replacement, sinusitis, peritonitis in dialysis patients, and cutaneous infections. Disseminated infection, pneumonia, cellulitis, and kidney infection have also been reported in immunocompromised patients. Recent outbreaks of P. lilacinus in cutaneous infections have been reported in neutropenic patients and deep seated infections in bone marrow transplant recipients have also been traced to contaminated hand lotion solutions.
Penicillium species are very large and ubiquitous genus with worldwide distribution over a broad range of climates in soil, decaying vegetation, and foods. They are the most abundant genus of mesophilic fungi in temperate soils. About 200 species have been identified. Their role in these habitats is to act as decay fungi; they are important agents in the natural processes of recycling used biological material. Penicillium species are indoor contaminants commonly found in carpet, wallpaper, and inside fiberglass duct insulation. High culturable or spore trap air counts may be detected where water damaged materials such as drywall, wallpaper, wood, and wood products are present.
Disease Associations: Penicillium marneffei is the only Penicillium species to cause important human disease in immunocompetent individuals. The dimorphic mould is restricted to Asia (Southeast and Far East) where it is considered an indicator of AIDS. This mould may cause hypersensitivity pneumonitis, allergic alveolitis in susceptible individuals. Penicillium species other than P. marneffei rarely cause disease even among immunocompromised hosts. Many species of Penicillium produce mycotoxins. In recent years the role of Penicillium species in indoor air quality has been established as a cause of allergenic reactions in some persons.
Phaeoannellomyces werneckii (Exophiala werneckii) causes tinea nigra, a superficial cutaneous fungal infection typically involving the palm of the hand or soles of the feet. The fungus is differentiated from other dematiaceous moulds by its salt tolerance, lack of growth at 37° C, and the wide densely septate, thick-walled brown hyphae.The infection is endemic in tropical and subtropical coastal regions in the Caribbean, Central and South America, Asia, and Africa. Cases have been reported from southeastern U.S. coastal states and Europe. Most infections are usually acquired in subtropical coastal locations. Being a salt-tolerant organism, infection is postulated to occur through exposure of superficially abraded skin to drying tidal pools. Children and young adults are most frequently affected, and most infections are reported from non-immunocompromised persons.
Phialophora species are dematiaceous (pigmented) mould found in decaying wood, wood pulp, and in the soil. These fungi are distinguished fromExophiala by having distinct collarettes and absence of yeast cells.Phialophora species have been implicated as causes of all of the disease classes caused by dematiaceous fungi: chromoblastomycosis, mycetoma, and phaeohyphomycosis. P. verrucosa is the second most common cause of chromoblastomycosis worldwide and the most common cause in North America.
Phoma species have worldwide distribution; commonly found in the soil and are considered plant pathogens (particularly in potatoes). Some species ofPhoma may produce pink or purple spots on painted walls due to their pigment production. Phoma species have been reported predominantly in cutaneous infections, but overall these fungi are rarely isolated from humans. This mould is reported to be allergenic in susceptible individuals.
The cosmopolitan fungus Pithomyces is often found in decaying wood, plant material, and the soil. A dematiaceous fungus that is distinguished from Alternaria and Ulocladium species by its scarcely differentiated conidiophores and its conidia which retain an annular frill at the base upon liberation. This fungus has not been documented as an etiologic agent of disease; however, it has been reported in cutaneous lesions in immunocompromised patients.
Pseudallescheria boydii (teleomorph or sexual name) has worldwide distribution being commonly isolated as saprobe from rural soils, sewage and contaminated water, and from the manure of farm animals. The ascomata (cleistothecia) are rarely produced in culture and the fungus is recognized by a synanamorph (Graphium) microscopic morphology and the production of conidiogenous cells/conidia (anamorph – Scedosporium apiospermum).
Disease Associations: The species is frequently involved in arthritis, otitis, and has been reported in cutaneous and ophthalmic cases. Cases have been reported after severe trauma due to traffic accidents, or after aspiration of polluted water due to near-drowning. As an emerging opportunist, serious infections by P. boydiihave increased in the last few years among patients with hematologic disease, particularly those recipients undergoing bone marrow transplant. Allergic bronchopulmonary disease has also been attributed to P. boydiiinfection.
Puciola spp. are dematiaceous (dark pigment) hyphomycete moulds found originally in sandy soil. This fungus appears so unusual in its features and particularly in its conidiophores and conidiogenous cells which is unlike other dematiaceous hyphomycetes. Its most distinctive features are the needle-shaped erect brown conidiophores and its peculiar conidiogenous cells.
Rhizopus species are ubiquitous fungi commonly found in the soil. They have been isolated from decaying fruit and vegetables, compost, old bread, and cereals. Some species are plant pathogens. A member of the Order Mucorales of the Zygomycetes, Rhizopus species are rapidly growing fungi on laboratory media and are distinguished from Mucor by its formation of rhizoids (root-like structures). The spores of Rhizopus may become easily airborne by the slightest disruption of the colony on an agar plate or from building materials.
Disease Associations: The major clinical settings for disease (Zygomycosis) with Rhizopus species are rhinocerebral and pulmonary, due to the inhalation of spores and subsequent dissemination from the respiratory tract. A primary predisposing factor is poorly controlled diabetes mellitus, especially when ketoacidosis is present. Nosocomial infections have resulted from aerosol contamination of air-conditioning systems and wound dressings. R. arrhizus is the most frequent agent of rhinocerebral zygomycosis and R. microsporus var. rhizopodiformis accounts for 10% to 15% of human zygomycotic disease, primarily cutaneous and gastrointestinal infections. Zygomycoses are rare in healthy individuals, unless traumatic implantation (e.g. wounds) has allowed a portal of entry for the fungus.
Rhodotorula species can be isolated from a variety of environmental sources. These include soil, air, water, cooling coils, drain pans, plants, dairy products, fruit juices, shower curtains, and toothbrushes. These fungi have also been isolated from human skin, urine, stool, and respiratory secretions. Rhodotorulais a genus of yeast-like fungi that produces carotenoid pigments ranging from a yellowish to red that can be observed with individual colonies on laboratory media.
Disease Associations: Confirmed cases of human infection are rare. Humans may be colonized with Rhodotorula, but it is usually transient. The most commonly reported infection due to Rhodotorula is fungemia. Rhodotorula fungemia most commonly occurs in patients with central venous catheters. There are also reports, however, of endocarditis, meningitis, peritonitis, and eye infections especially in the high risk patient (e.g. immunosuppressed). This yeast has been reported to be allergenic.
The Rusts are a complex group of fungi belonging to the order Uredinales of the class Basidiomycetes. The 5,000-7,000 species are rather strict parasites of trees, flowering plants, grasses, crop plants, and other plant material. The rust fungi produce different types of sexual basidiospores, namely urediospores, teliospores, pycniospore, and aeciospores. Many of the rusts spores are capable of wind distribution and may be carried by wind currents hundreds of miles in some cases. Puccinia is the most common of the rust fungi, which has unicellular, orange summer urediospores and brown, two-celled, over-wintering teliospores. The rust fungi cannot grow indoors unless their host plants are present.
Some of the rust fungi are very distinctive in appearance and may be easily recongized on spore trap or tape lift slides. The rusts cannot be cultured on ordinary laboratory media. The rust fungi are known to cause allergy in the susceptible host, but they have not been documented as an etiologic agent of disease in humans or animals. The rust fungi are of great economic interest on account of their harmful effects on many important crops. The rusts are not known to produce mycotoxins.
The most common species of this group is S. brevicaulis with worldwide distribution in soils, plants, feathers, and insects. S. brumptii is a common soil fungus and has been isolated from a variety of materials including house dust. Scopulariopsis species are distinguished from Penicillium species by their formation of pyriform conidia, typically with a truncated base. S. brumptiihas caused pulmonary hypersensitivity and possible mycetoma of a foot.Scedosporium speciesScedosporium apiospermum (teleomorph or sexual name – Pseudallescheria boydii) has worldwide distribution being commonly isolated from rural soils, sewage and contaminated water, and from the manure of farm animals.Scedosporium prolificans has been isolated from soil samples.
Disease Associations: Two forms of disease have been described: invasive disease caused by bothScedosporium species and mycetoma caused only by Pseudallescheria boydii. As an emerging opportunist, serious infections by P. boydii have increased in the last few years among patients with hematologic disease, particularly those recipients undergoing bone marrow transplant. Scedosporium prolificans can be introduced traumatically into persons via thorns or splinters; and thus may be frequently isolated from cutaneous and subcutaneous lesions. Since 1990 more cases of disseminated disease in immunocompromised patients are being reported.
Sporidiobolus species (Sporobolomyces is the anamorph name) are basidiomycetous yeasts being characterized by carotenoid pigments observed in culture ranging from pink to red or orange. These yeasts may be recovered from soil, from air, and from other environmental sources such as leaves, bark, grasses, and fruit. Only rarely a cause of clinical disease in humans, S. salmonicolor has been reported in several instances of disease involving asthma, dermatitis, extrinsic allergic alveolitis, lymphadenitis, and bone marrow involvement in AIDS patients.
Sepedonium species are cosmopolitan mould that are found in soil as a saprobe and are known to parasitize certain mushrooms. No cases of infection have been reported in humans or animals to date.
Sphaerobolus stellatus – Artillery Fungus
S. stellatus causes the tiny dark spots on houses (siding), cars, and plants. They are actually spores from a group of fungi commonly called the “cannonball” or “artillery” fungi in the genus Sphaerobolus. Sphaerobolusbelongs to the Basidiomycetes which include the mushrooms, smuts, rusts, puffballs, and bracket fungi. The fungi appear as yellow-brown to black, disk-shaped spots of 1-2 mm. The fungi can be detected on nearly any surface due to a sticky substance that allows for good adherence. The fungus is sensitive to light and “shoots” its black, sticky spore mass towards white or light-colored surfaces such as house siding, white cars or other bright light-reflecting bases. The spore mass may be projected as high as the second story of a house. The spore mass sticks to the side of a building or parked automobile resembling a small speck of tar. The spore mass can also be found on the underside of leaves on plants growing in mulched areas. The artillery spores do not usually structurally damage the houses, cars, plants, etc. they cover. Once attached, it is very difficult to remove without damaging the surface. If removed, it leaves a stain. Scrubbing and scraping with tools or harsh chemicals may damage painted o r otherwise colored surfaces. To date, there are no known remedies for the fungus.
Sporotrichum species have widespread distribution occurring in decaying wood and in the soil. Sporotrichum species are the anamorphs (asexual stage) of basidiomycetous fungi which are important agents of wood decay.S. pruinosum appears to be potentially pathogenic in the respiratory tract since a few cases of repeated isolations from respiratory secretions are suggestive of bronchopulmonary colonization.
Sporotrichosis is caused by the soil dimorphic fungus Sporothrix schenckii. It is usually a chronic infection of the skin and subcutaneous tissue. Sporotrichosis is global in distribution but is found primarily in temperate zones of North America, South America, and Japan. Infection usually occurs by direct skin inoculation from contaminated soil or thorned plants such as roses. Outbreaks of infection have been associated with contaminated plant material such as straw, wood, hay bales, and sphagnum moss. Most cases are associated with vocational or recreational exposures. Sporothrix cyanescens (a saprophytic species) has been implicated in one case of sporotrichosis in an immunocompromised patient.
Stachybotrys species are cosmopolitan, saprophytic fungi with worldwide distribution and can be found on paper, seed, in soil, textiles, decaying plant material, and other cellulose rich materials. Major indoor habitats include water-damaged wallpapers and jute carpet backing, carpet glues, ceiling tile, water-soaked wood, wall paneling, gypsum board, plus moist debris in ducts and damp papers and books. Stachybotrys species will not grow on vinyl, plastic and concrete products or ceramic tiles. They are slow growing mould on laboratory media and do not compete well with other rapidly growing fungi. They may be readily found in most buildings that have experienced chronic water problems that are left unattended. The spores of Stachybotrys are not readily airborne therefore, bulk or swab sampling can be important for detecting the fungus indoors.
Disease Associations: Stachybotrys species are known to produce secondary metabolites called mycotoxins that, when ingested, inhaled, or come in contact with skin are harmful to animals and humans. Mycotoxins generally have low volatility; therefore, inhalation of volatile mycotoxins is not likely to occur. The mycotoxins, however, are an integral part of the fungus (e.g. spores, hyphal fragments). It has been known for a long time that animals consuming Stachybotrys contaminated hay have experienced acute manifestations characterized by a variety of neurologic signs, such as tremors, incoordination, and impaired or loss of vision. Other chronic manifestations such as dermonecrosis, leucopenia, gastrointestinal ulceration, and hemorrhage have also been noted.Although mycotoxins (specifically macrocyclic trichothecenes) were isolated from the contaminated hay in the human and animal intoxications, current illnesses in humans occupying Stachybotrys-contaminated buildings are not yet proven to be related to these toxic products.Recently, two researchers presented a study in Brescia, Italy, at the Eighth International Symposium on Neurobehavioral Methods and Effects in Occupational and Environmental Health (June 2002) outlining 43 sick buildings with 105 patients (Ritchie Shoemaker, M.D., of the Center for Research on Biotoxin Associated Illnesses in Pocomoke City, MD). Dr. Shoemaker has stated: “We have terrific documentation that a number of people working in a mold-contaminated building experienced similar illnesses, response to treatment, and relapse to re-exposure”.
Syncephalastrum species belong to the Order Mucorales of the Zygomycetes. These fungi are commonly isolated from animal dung and soil in tropical and subtropical countries. The fruiting structures may superficially resemble and are often mistaken for those seen in the aspergilli. These fungi are very rarely associated with human disease but have been reported in cutaneous infections. Rarely causes human infection, but cases of onychomycosis (nail), skin lesions, and opportunistic invasive disease in the immunocompromised hosts have been reported.
Torula is a cosmopolitan dematiaceous fungus and appears to be most frequent in temperate regions of the world. The fungus has been isolated from a variety of sources including dead herbaceous stems, leaves, wood, soil, air, and many plant substrates such as sugar beet roots, groundnuts, seeds of oats, bean pods, and cultivated grasses. Torula has a distinctive appearance on spore trap slides and tape preps. Although being allergenic, the fungus has not been reported to cause disease in humans.
Trichoderma species have widespread distribution and are commonly found in soil, wood, fallen timbers, decaying vegetation, pine needles, and paper. They are known to readily degrade cellulose. Indoors, the mould may be isolated on paper tapestry in kitchens, unglazed ceramic surfaces, house dust, and stored grains. Trichoderma viride is an emerging pathogen in the immunocompromised host with underlying diseases such as leukemia, organ transplants, chronic lung disease, chronic renal disease, and in patients undergoing continuous peritoneal dialysis. This fungus may cause Type 1 allergy inhalation in the sensitized individual and is known to produce potent metabolites (e.g., mycotoxins).
Trichothecium roseum has a wordwide distribution and is commonly found on decaying plant material, in soil, and on many kinds of grains and nuts. T. roseum forms characteristics pink colonies on agar media and produces two-celled clavate conidia in a zigzag formation on long conidiophores. It has been considered a primary pathogen of stored apples and tomatoes in a greenhouse. The mould has not been documented as a etiologic agent of human or animal disease.
Trichosporon species are yeast-like fungi that may be isolated from soil, water, vegetables, mammals and birds. They can also be isolated in the mouth, on the skin and nails of humans. They are generally associated with water intrusion in the indoor environment. There have been 17 named species reported and about six have been associated with human disease. Among the species most often reported to cause human disease is Trichosporon beigeli. Superficial infections include infection of the hair shaft (called white piedra), and less commonly, onychomycosis (nails). Deep-seated infections may be either localized or disseminated. Disseminated disease has been reported in patients with hematologic malignancies, burns, and organ transplants.
Tritirachium species are widespread in decaying vegetation and in the soil. They are an insect pathogen. The mould must be differentiated from Beauveria and Engyodontium album. This fungus has been reported to cause corneal ulcers and a case of otomycosis. They have also been isolated from a catheter tip.
Ulocladium species are cosmopolitan fungus commonly found in the soil and on decaying herbaceous plants, paper, textiles, and wood. A dematiaceous(darkly pigmented) fungus that produces muriform conidia having septa in more than one plane. The fungi in this group include Alternaria, Stemphylium, Pithomyces, Ulocladium, and Epicoccum species. Only Alternaria has been convincingly involved in human disease. Although Ulocladium species are common contaminant, their presence indoors may indicate moisture intrusion. If given the right circumstances, Ulocladium species may cause opportunistic infection. They have been reported in subcutaneous infections.
Ustilago species are yeast-like fungi belonging to the order Ustilaginales of the Basidiomycetes. The mould has been found as a major pathogen of plants including cereal grains, flowering plants, and rich organic materials. The teliospores (sexual phase) of the fungus can be detected by spore trap slides, but differentiation from Myxomycetes and Periconia is difficult. They are generally reported on a spore trap results as "Smuts/Myxomycetes/Periconia." The basidiospores yeast-like form ofUstilago cannot be recognized on a spore trap preparation, but it can be identified on routine fungal media from viable air sampling and by microscopic exam in the laboratory.
Verticillium is a widely distributed filamentous hyphomycete fungus inhabiting decaying vegetation and soil. Some species are parasitic on other fungi, arthropods, and plants. Verticillium rarely causes disease in humans. A pathogen of various plant species and may be a possible cause of human keratitis.