Types of Mold

A zygomycate reported to be allergenic has been shown on occasion to cause infections at multiple sites. According to the study of Microbiology and Immunology On-line, the Absidia species is one of the three most common genera that can cause Zygomycosis which also known as mucormycosis and phycomycosis. Zygomycosis is an acute inflammation of soft tissue, usually with fungal invasion of the blood vessels. This rapidly fatal disease is caused by several different species in this class. The zygomycetes, like the Candida species, are ubiquitous and rarely cause disease in an immunocompetent host. Some characteristic underlying conditions which cause susceptibility are: diabetes, severe burns, immunosuppression or intravenous drug use. Another common health effect of absidia species, is Rhinocerebral infections. This disease is frequently seen in the uncontrolled diabetic.

These fungi have a tendency to invade blood vessels (particularly arteries) and enter the brain via the blood vessels and by direct extension through the cribiform plate. Rhinocerebral infections are usually fulminant and frequently fatal. This is why they cause death so quickly.

Absidia species may also cause mucorosis in immune compromised individuals. Mucurosis is an infection with tissue invasion by broad, nonseptate, irregularly shaped hyphae of diverse fungal species such as Absedia species. The sites of infection are the lung, nasal sinus, brain, skin and eye (Mycotic Keratitis-infection of cornea which can lead to blindness). Infection may have multiple sites. One species of Absidia which is the Absidia cormbifera has been an invasive infection agent in AIDS and neutropenic patients, as well as, agents of bovine mycotic abortions, and feline subcutaneous abscesses.

Reported to be allergenic. Can produce a trichothecene toxin which is toxic if ingested. It was the primary fungus identifired in at least two houses where the occupant complaints were nausea, vomiting, and diarrhea. A sexual state of Emericellopsis, Chaetomium, Nectripsis. It can produce mycetomas, infections of the nails, onychomycocorneal ulcers, eumycotic mycetoma, endophthalmitis, meningitis, and endocarditis. Species of Acremonium are recognized by solitary to weakly branched, tapering phialides arising from vegetative filaments and bearing a wet cluster of mostly 1-celled spores (conidia). The filaments are sometimes bound together into “ropes” several cells in diameter. Some appear to be parasitic on living fungi. Sequence characteristics of this imperfect fungus are of great interest as prerequisite for the improvement of antibiotic biosynthesis.

Acremonium, under certain conditions, can also produce very potent mycotoxins called trichothecenes. The trichothecenes are potent inhibitors of DNA, RNA, and protein synthesis, and have been well studied in animal models because of concern about their potential misuse as agents of biological warfare, due to their ability to destroy the immune system, internal organs, bone marrow, and affect the mind. They are a known carcinogen. The most common characteristic of this fungus is a horrible stench in the air. This fungus is often associated as an aftermath of stachybotrys chartarum. It was the primary fungus identified in several homes where the occupants complaints were nausea, vomiting and diarrhea. Asexual state of Emericellopsis sp., Chaetomium sp., and Nectripsis sp.. It can produce mycetomas, infections of the cornea and nails.

Acrodontium salmoneum:
Reported to be a fairly common airborne fungus and is considered to be allergenic. Can produce a trichothecene toxin which is toxic if ingested. It was the primary fungus identified in at least two houses where the occupant complaints were nausea, vomiting, and diarrhea. It can produce mycetomas, infections of the naild, onychomycosis, corneal ulcers, eumycotic mycetoma, endophthlmitis, meningitis, and nedocardities. It is the asexual state of Emericellopsis, Chaetomium, and Nectripsis.

Characteristics: Allergenic/Toxigenic/ Some species are Toxigenic/Pathogenic. A very common allergen with an IgE mediated response. It is often found in carpets, textiles and on horizontal surfaces in building interiors. Often found on window frames. Outdoors it may be isolated from samples of soil, seeds and plants. Commonly found in outdoor samples of soil, seeds, and plants. The large spore size 20-200 microns in length and 7-18 microns in sizes, suggests that the spores from the fungi will deposit in the nose, mouth and upper respiratory tract. It may be related to bakers asthma. It has been associated with hypersensitivity pneumonitis. The species is capable of producing tenuazonic acid and other toxic metabolites which may be associated with disease in humans or animals. Common cause of extrinsic asthma (immediate-type) hypersensitivity: typeI). Acute symptoms include edema and bronchiospasms; chronic causes may develop pulmonary emphysema. Alternaria has a unique group of mycotoxins, including alternariols, altenuenes, altertoxins, tenuazonic acid, and AAL toxins. Alternariols and altenuenes are weakly toxic to mice and are cytotoxic (toxic to cultured human cell lines) in vitro at concentrations between 6 and 28 ug/ml (15). Altertoxins and the related compound stemphyltoxin-III, also produced by Alternaria, are mutagenic. Tenuazonic acid (Chemical name: 2H-Pyrrol-2-one, 3-acetyl-1,5-dihydro-4-hydroxy-5-(1-methylpropyl)-, (S-(R*,R*))-) appears to inhibit protein synthesis by preventing newly formed protein molecules from detaching from the ribosomes on which they formed.

It is lethally toxic to young birds, and in administration to animals produced effects such as “salivation, emesis (vomiting), anorexia (avoidance of eating), erythema (red skin flush), gastrointestinal haemorrhage, convulsions, increase in packed cell volume (an immune parameter) and many other effects” (15). AAL toxins appear to have limited toxic effects against some cultured mammalian cell lines, but are mainly of significance in invasions of plants by Alternaria phytopathogens.

Acute symptoms include edema and bronchi spasms, chronic cases may develop pulmonary emphysema. As with other toxigenic molds, alternaria can also alter DNA, as well as destroy the human immune system.

Conidia dimensions is about 18-83 x 7-18. Large spore size 20-200 x 7-18 suggest that the spores from this fungi will be deposited in the nose, mouth, gut, and upper respiratory tract. Aphanoscus fulvescens: Extremely widespread in soil, animal skin scrapi and dung. Is often associated with birds nests and feathers. Should be considered an allergen. This fungus has also been documented in skin infections. No toxic related diseases are of record to date.

Apophysomyces elegans: Extremely widespread in soil and decaying vegetation. Should be considered an allergen. This fungus has also been documented in various zygomycosis including necrotizing fascitis, osteomyelite and angioinvasion. Most cases are acquired through the tramatic implantation of the fungus. No toxic related diseases are of record to date.

A cosmopolitan filamentous fungus isolated from plant debris and soil. Common on dead plants, especially grasses and sedges, they are often isolated from air near grassy places in the autumn. There are no infections so far reported due to Arthrinium in humans or animals.

This genus of fungi are classified as dematiaceous ascomycetes most commonly isolated from dung. They are not generally associated with human disease and are most often considered benign.

Extremely widespread in soil and decaying vegetation. Arthrographis cuboidea and A. kalrae should be considered to be allergens. A kalrae has been documented in onychomycosis and has been recovered from skin, nails, and respiratory sites but has not been established as an etiological agent. No toxic related diseases are of record to date.

One of the major classes of fungalorganisms. This class contains the “sac fungi” and yeasts. Some ascomycete spores can be identified by spore morphology, however; some care should be exercised with regard to specific identification. Many ascomycete spores are reported to be allergenic.

Ascospores (Ascomycetes):
Characteristics: Allergenic. Fungal spores which are from mushrooms. The specific mushroom species can not be identified on the culture plate. Many mushroom spores are reported to be allergenic. Terms discussed: ascospore (pl. ascospores), basidiospore (pl. basidiospores), chlamydospore (pl. chlamydospores), endosporium, episporium, exosporium, mesosporium, peripheral envelope, perisporium, zygospore (pl. zygospores)

A large category of spores (produced in a sac-like structure) that are found everywhere in nature and include more than 3000 genera. Most Ascospores of health or IAQ importance are identified separately by their genus (e.g. Chaetomium) when possible on a IAQ report, and the Ascospore category is used primarily on these reports for a large group of less important spore types often found in quantity on outdoor air samples. On tape samples, Ascospore is sometimes also used as a general morphological identification (i.e. the ascus or sac structure is present) for certain samples in those cases when the spores do not appear to represent any of the IAQ significant genera.

Aspergeillus (Apergeillus/Penicillium):
Characteristics: Allergenic. A wide number of organisms have been placed in the genus. Identification species is difficult. Often found in aerosol samples. Commonly found in soil, food, cellulose, grains, paint, compost piles, carpet, wallpaper and in interior fiberglass duct insulation. It is reported to be allergenic and may cause hypersensitivity pneumonitis, allergic alveolitis in susceptible individuals. Members of the genus are reported to cause ear infections. Many species produce mycotoxins, which may be associated with disease in humans and other animals. Toxin production is dependent on the species or a strain within a species and on the food source for the fungus. Some of these toxins have been found to be carcinogenic in animal species. Several toxins are considered potential human carcinogens. Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms; chronic cases may develop pulmonary emphysema. Aspergillosis is a large spectrum of diseases caused by members of the genus Aspergillus. The three principal entities are: allergic bronchopulmonary aspergillosis, pulmonary aspergilloma and invasive aspergillosis [see below]. According to a recent Mayo Clinic study, one in seven Americans suffers from acute fungal sinusitis. These numbers are sounding alarming. Colonization of the respiratory tract is also common.

Lowered host resistance due to such factors as underlying debilitating disease, neutropenia chemotherapy, disruption of normal flora, and an inflammatory response due to the use of antimicrobial agents and steroids can predispose the patient to colonization, invasive disease, or both. Aspergillus spp. are frequently secondary opportunistic pathogens in patients with bronchiectasis, carcinoma, other mycoses, sarcoid, and tuberculosis.


Background Debris:
Background debris is an indication of the amount of non-biological particulate matter present on the slide (dust in the air) and is graded from 1+to 4+ with 4+ indicating the largest amounts. To evaluate dust levels it is important to account for differences in sample volume. This background material is also an indication of visibility for the analyst and resultant difficulty reading the slide. For example, high background debris may obscure the small spores such as the Penicillium/Aspergillus group. Counts from the areas with 4+ background debris should be regarded as minimal counts and may actually be higher than reported.

One of the major classes of fungal organisms. This class contains the mushrooms, shelf fungi, puffballs, and a variety of there macrofungi. It is extremely difficult to identify a specific genera of mushroom using standard culture plate techniques. Some basidiomycete spores can be identified by spore morphology, however; some care should be exercised with regard to specific identification. Many basidiomyucete spores are reported to be allergenic.

Has been isolated from decaying plants, soil, and from the female materials of frogs, reptiles, fish, and bats. The relationship of these organisms from human occupied spaces potentially suggests a common present of this general fungi in the indoor environments. Should be considered allergenic. Basidiobolu ranarum rarely causes disease, but has principally been involved with trunk and extremity infection of children in tropical countries. No toxic diseases have been documented to date.

Characteristics: Allergenic. Fungal spores which are from mushrooms. The specific mushroom species can not be identified on the culture plate. Many mushroom spores are reported to be allergenic.

Widespread in the soil with various species being parasites of insects, the most notable being Beauveria bassiana which affects the silkworm. Not considered to be common to indoor environments. Should be considered allergenic. Reproted to cause mycotic keratitis and occasional pulmonary infections. No toxic diseases have been documented to date. Bipolaris: A widespread fungus that is most frequently associated with grasses, plant material, decaying food, and soil. It is common to both indoor and outdoor environments. Older obsolete names include Drechslera and Helminthosporium. This fungus produces large spores which would be expected to be deposited in the upper respiratory tract. Various species of this fungus will produce the mycotoxin – sterigmatocystin which has been shown to produce lung and kidney damage when ingested by laboratory animals.

Bipolaris/Drechslera Group:
Characteristics: Common Type I allergies (hay fever, asthma). Other: Most commonly reported cause of allergic fungal sinusitis. There is a potential to be opportunistic or a pathogen. Occasionally there is evidence that this mold group can cause phaeohyphomycosis, including keratitis, sinusitis, and osteomyelitis. These infections most often occur in immunocompromised persons, although infections also occur in normal hosts. One case of brain abscess reported in an immunocompromised patient. This group is ubiquitous and found in cosmopolitan locations. Some species are more commonly found I tropical or subtropical areas.

Blastomyces dermatitidis – Rare environmental isolates has been found in moist soil with high organic content. Important human pathogens. It is a thermally dimorphic fungus which has filamentous fungus when grown 25 degrees C and a yeast form at 37 degrees C. Causes Blastomycosis in humans and animals involving pulmonary invasion, followed by cutaneous, osteoarticulate and genitourinary diseases. No toxic diseases have been documented to date. Blastoschizomyces: Blastoschizomyces capittus found in the soil, sand, as a normal flora of the skin, respiratory and digestive tracts of human lining. Invasive and disseminated infections have been reported in immunocompromised toxic diseases have been documented to date.

Characteristics: Type I allergies (hay fever, asthma). Type III hypersensitivity pneumonitis: Eg. Winegrower’s lung. Its distribution is ubiquitous. Primarily found in temperate and subtropical regions. There are approximately 30 species. It is found in soil, and stored and transported on fruits and vegetables. It is a plant pathogen and saprophyte on flowers, leaves, stems, fruits. It causes leaf rot on grapes, strawberries, lettuce, cabbage, onions. It’s mode of transport is dry spore, wind, and also liberated by rain splash. It’s growth indoors may be found in conjunction with indoor plants. Aw=0.93-0.95 (minimum for various species). With spore trap recognition it is fairly distinctive, frequently with a visible inner cell wall, and an attachment point at one end. Spores are slightly pigmented.


This genus contains a variety of organisms that have been isolated from the environment, as well as human akin and mucous membrane.

Characteristics: Allergenic/Pathogenic. Description: Large ascomycetous fungus producing perithecia. It is found on a variety of substrates containing cellulose, including paper and plant compost. It has been found on paper in sheetrock. It is reported to be allergenic. It can produce an Acremonium like state on fungal media.

Widespread, common in the soil and on plants. Rare agents of onychomycosis, skin lesions, endocarditis, and uncommon agents of the pulmonary mycosis adiaspiromycosis. No toxic diseases have been documented to date.

Widespread, common in the soil and on plant debris. C. bantiana has been reported as a neurotropic agent causing cerebral phaeohyphomycosis in the form of brain abscesses. Skin lesions have also been reported. The organisms have also been recovered from pulmonary sites. C. bantiana has been associated with skin lesions and a possible cause of chromoblastomyhcosis. C. carrionii is almost exclusively associated with chromoblastomycosis, which is generally restricted to subtropical areas. Most patients have had long-term soil exposure with repeated trauma and tissue injuries to the feet and legs. No toxic diseases have been documented to date.

Aw (water activity) in the range of 0.84 to 0.88. Most commonly identified outdoor fungus. The outdoor numbers are reduced in the winter. The numbers are often high in the summer. Often found indoors in numbers less than outdoor numbers. It is common allergenic. Indoor Cladosporium sp. may be different than the species identified outdoor is commonly found on the surface of fiberglass duct liner in the interior of supply ducts. A wide variety of plants are food sources for this fungus. It is found on dead plants, woody plants, food, straw, soil, paint and textiles. It can cause mycosis. Produces greater than 10 antigens. Antigens in commercial extracts of variable quality and may degrade within weeks of preparation. Common causes of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms, chronic cases may develop pulmonary emphysema. Cladosporium cladosporioides.

Colonies around 3 cm in 7 days on PDA, olivaceous grey-green to olivaceous brown, reverse olivaceous black. Conidiophores branching widely and giving rise to numerous clusters of blastoconidia in branching chains, with larger conidia near the base of the chain and smaller conidia near the apex. Conidia 1- or rarely 2-celled, mostly smooth walled or minutely roughened, bluntly forked near the apex if they have given rise to 2 or more apical daughter cells or chains, or ellipsoidal to lemon shaped if they have not, 3 – 7 (-11) X 2 -4 (-5) µm, with cicatrized (darkened), slightly protuberant scars at the places where they have been attached to other conidia or the conidiophore.

Toxins: the antifungal compound cladosporin is produced, as well as emodin, an anthraquinoid pigment compound which on breakdown in vitro by hepatic microsomes forms 2-hydroxyemodin, a mutagenic and cytotoxic product, and some other compounds of lower toxicity. Cultures fed to mice appeared to result in the death of the mice from hemolytic jaundice and renal failure. There has been no evidence so far, however, of a toxic effect associated with inhalation of conidia, e. g. in indoor mold proliferation cases.

Cladosporium sphaerospermum:
Morphology: similar to C. cladosporioides but with conidia, especially those formed near the ends of chains, much more strongly rounded 3 – 4 (- 7) µm in diameter. Typical isolates have strongly roughened conidia, but some smooth-conidial types are seen. Probably consists of a complex of similar species. This mold is somewhat common in homes, with a number of people who have allergies showing symptoms from spores of this mold.

Toxins: toxic effects have been noted, e. g., against chicken embryos, but chemicals responsible have not been thoroughly characterized. Not regarded as a highly toxic organism. Cladosporium spp. have been known to be causative agents of skin lesions, keratitis, onychomycosis, sinusitis and pulmonary infections.

Cladosporium herbarum Morphology: similar to C. cladosporioides except that:
Conidiophores have distinct “geniculate elongations”, that is, places where they have thickened up and produced one or more conidiogenous apertures, but then the conidiophore has continued to grow out at a slight angle, making a knee-joint-like bend (whence the term “geniculate”) which technically constitutes a sympodial proliferation. Long, mature conidiophores may have a number of geniculate bends along their lengths. Cladosporium herbarum has a teleomorph, Mycosphaerella tassiana.

Conidia are larger and more often 2-celled; one-celled conidia are 5.5 – 13 X 3.5 – 6 µm, distinctly roughened.

Toxins: so far, not considered significantly toxic to humans.

Cryptostroma corticale:
Conidia dimensions 12-47 x 10 microns. It is found on the leaves of tomatoes.

Can cause disseminated and pulmonary infections in immune compromised hosts.

Reported to be allergenic. It may cause corneal infections, mycetoma and infections in immune compromised hosts.


Conidia (spores) dimensions 40-120 x 17-28 microns. Four on grasses, grains and decaying food. It can occasionally cause a corneal infection of the eye.


Emericella nidulans:
A ubiquitous soil fungus. Most often isolated from tropical and subtropical climates. Perfect stage of Aspergillus nidulans. This fungus should be considered allergenic. No toxic or invasive diseases have been reported to date.

Characteristics: Allergen: Common. Type I allergies (hay fever, asthma)

Potential Opportunist or Pathogen: No cases of infection have been reported in humans or animals.

Potential Toxin Production: Antibiotic substances produced: flavipin, epicorazine A & B., indole 3-acetonitrile.

Description: Mode of Dissemination: Dry spore carried by the wind. Spores also released by hygroscopic movement.

Growth Indoors: Yes, on many different substrates including paper, textiles, and insects.

Aw=0.86-0.90 (minimum)

Notes on Spore Trap Recognition: Intact spores are distinctive. Young spores or spore fragments may be confused with Ulocladium, Stmphylium or possibly Alternaria. Commonly found in outdoor air.

Can cause infections of skin and nails.

Eurotium amstelodami:
This fungus is frequently encountered in tropical and subtropical regions. It is frequently reported from soils and dried or concentrated food products. It is the perfect stage of Aspergillus amstelodami. This fungus shold be considered allergenic. No toxic or invasive diseases have been reported to date.


Fusarium solani:
Aw (water activity) 0.90. Macroconidia (spores) dimensions 27-52 x 4.4-6.8; Microconidia dimensions 8-16 x 2-4 microns. Found in plant and soils. Can produce trichothecene toxins which may be associated with disease in humans and animals.

Aw (water activity) 0.90. A common soil fungus. It is found on a wide range of plants. It is often found in humidifiers. Several species in this genus can produce content trichothecene toxins (5, 27). The trichothecene (scirpene) toxin targets the following systems: circulatory, alimentary, skin, and nervous. Produces vomitoxin on grains during unusually damp growing condition. Symptoms may occur either through ingestion of contaminated growth or possibly inhalation of spores. The genera can produce hemorrhagic syndrome in humans (alimentary toxic aleukia). This is characterized by nausea, vomiting, diarrhea, dermatitis, and extensive internal bleeding. Reported to be allergenic. Frequently involved in eye, skin and nail infections.


Aw (water activity) 0.90. Conidia (spores) dimensions 6-1 x 3-6 microns. Aw (water activity) 0.90. A common contaminant of grains, fruits, and dairy products, paper, textiles, soil and water, and often present as part of the normal human flora. The species Geotrichum candidum can cause a secondary infection (geotrichosis) in association with tuberculsis. This rare disease can cause lesions of the skin, bronchi, mouth, lung, and intestine.

A fungus which is structurally similar to Penicillium. It is reported to be allergenic.

Characteristics: No information is available regarding health effects or toxicity. Allergenicity has not been studied.

Gonatobotryum species are common in certain ecological niches. They are parasitic on Ceratocystis, and so are found where Ceratocystis is found, most particularly lumber. Most homes built with lumber have areas of growth of both Ceratocystis and Gonatobotryum on wood framing inside walls. (Virtually all lumberyards have some percentage of boards with areas of this black mold growth). No information is available regarding health effects or toxicity. Allergenicity has not been studied. May be identified on surfaces by tape lifts, tease mounts from bulk samples, and in air by spore trap samples. (Spores have distinctive morphology.) Other natural habitats include soil, and rotten wood. Also parasitic on certain other plants.


Reported to be allergenic.

A fungus which has filamentous growth at 25 degrees C and yeast growth at 37 degrees C. It is reported to be a human pathogen. It may be associated with birds.

Grow on products with a high cellulose content. These fungi are also found in soil and on plant debris.

Hyaline Mycelia:
Sterile mycelia which is white or transparent. No fruiting structures are produced by the mycelia. Visual identification of these organisms is not possible. Often associated with allergic symptoms.

Laboratory results are reported to two significant figures for each genus/species count as well as for each total count. For this reason, summation of individual concentrations may not equal reported concentration.


Characteristics: Allergen not studied. Potential opportunist or pathogen not known. It has potential toxic production. Trichothecenes (trichodermol and trichodermin) and griseofulvins. Trichothecene toxicity is due to the ability to bind ribosomal protein. Griseofulvin has been made commercially available as an anti-dermatophyte drug.

Description: Mode of Dissemination: Dry spore carried by the wind.
Growth indoors: Yes, on many different substrates. It is very closely related to Stachybotrys. M. echinata produces acetic acid. This mold is very distinctive. It is frequently found in conjunction with Stachybotrys species.

Causes ringworm in humans

Reported to be allergenic. This fungus produces soft rot of tree fruits. Other members produce a red bread mold. It is infrequently involved in corneal eye infections.

Often found in soil, dead plant material, horse dung, fruits, and juice. It is also found in leather, meat, dairy products, and animal hair. Zygomycetes fungus which may be allergenic (skin and bronchial tests) (7, 1), This organism and other Zygomycetes will grow rapidly on most fungal media. May cuase mucorosis in immune comopromised individuals. The sites of infection are the lung, nasal sinus, brain, eye, and skin. Infection may have multiple symptoms.

Characteristics: Associated with type I allergies, but has not been associated with human infection or been known to produce toxins. They may cause problems if a person has had previous exposure and developed hypersensitivities.

Myxomycetes are not considered true fungi. These organisms have both dry and wet spores. Wind disperses the dry fruiting bodies.


Characteristics: Type I allergies (hay fever, asthma). Very rare report of human infection.

It is ubiquitous and found in cosmopolitan areas. It is especially abundant in warm climates. There are approximately 4-5 species. It is found in decaying plant material and soil. It travels by an active discharge mechanism. It does not require wind or rain. It is rarely found growing indoors. Negrospora has distinctive large, dark brown (nearly black), globose spore is readily identifiable on spore trap slides.


Characteristics: No information is available regarding health effects or toxicity. Alergenicity has not been studied.

Oidium is the asexual state of Erysiphe. Erysiphe species are plant pathogens, one of the genera causing powdery mildews. Erysiphe is very common and is an obligate parasite on leaves, stems, flowers, and fruits of living higher plants. The asexual phase Oidium may be identified in air on spore trap samples, (spores have distinctive morphology), although because obligate parasites cannot grow on non living environmental surfaces, our laboratory does not include Erysiphe on our spore trap report form. The asexual spores are also seen in dust.

Ophiostoma Ceratocysitis:
Characteristics: As an allergen is has not been studied. Persons most likely to be affected would be lumber-yard workers or carpenters. As a pathogen it has not been reported to infect humans or animals. A connection between Ophiostoma and the human pathogen Sporothrix schenckii has been proposed but not confirmed. There is no potential toxin production.

It grows indoors. Most homes built with lumber have areas of growth on wood framing inside walls. On spore trap recognition, it’s not identifiable. On rare occasions the spores of Gonatobotryum, which grows parasitically on Ceratocystis, are seen on spore trap samples (an indirect indication of the presence of this group of fungi). On swab or tape lift samples, it has a distinctive fruiting bodies with long necks are easily identifiable.


Commmonly found in soil and dust, less frequently in air. Paecilomyces variotii can cause paecilomycosis. Linked to wood-trimmers disease and humidifier associated illnesses. They are reported to allergenic. Some members of this genus are reported to cause pneumonia. It may produce arsine gas if growing on arsenic substrate. This can occur on wallpaper covered with particles of green.

This fungi is found in soil, textiles, decaying plants, manuals, and paper.

Characteristics: Not studied as an allergen. Rare case of mycotic keratitis reported. A potential for toxin production is not known.
Some species have distinguishing spore characteristics and are recognizable. Generally it is difficult to distinguish Periconia spore from the smuts, myxomycetes and certain species of Periconia.

A common indoor air allergen. It is similar to the early stages of growth of Chaetomium sp. The species are isolated from soil and associated plants (particularly potatoes). Produces pink and purple spots on painted wall (3, 17). It may have antigens which cross-react with those of Alternaria sp. 1 will grow on butter, paint, cement, and rubber. It may cause phaeohyphomycosis, a systematic or subcutaneous disease.

Grows on dead grass in pastures. Causes facial eczema in ruminants.


The Zygomycetous fungus is reported to be allergenic. It cause mucorosis in immune compromised individuals. It occupies a biological miche similar to Mucor sp. It is often linked to occupational allergy. The sites of infection are the lung, nasal, sinus, brain, eye, and skin. Infection may have multiple sites.

A reddish yeast typically found in moist environments such as carpeting, cooling coils, and drain pans. In some countries it is the most common yeast genus identified in indoor air. This yeast has been reported to allergenic. Positive skin tests have been reported. It has colonized in terminal patients.

Characteristics: Type I allergies (hay fever, asthma)

Rusts have both wet and dry spores. Wind disperses the urediospores, teliospores, basidiospores, and aeciospores. The basidiospores and aeciospores have an active spore release mechanism. Rusts do not grow indoors unless their host plants are present. They are parasitic plant pathogens and need a living host for growth. Rust urediospores and teliospores are airborne; they are distinctive and readily identifiable on spore trap slides.


Reported to be allergenic. Baker’s yeast.

Saprophytic fungi:
A Scopulariopsis It may produce arsine gas if growing on arsenic substring. This can occur on wall papers covered with paris green. It has been found growing on a wide variety of materials including house dust. It is associated with type III allergy.

Serpula lacrymans:
Common cause of extrinsic asthma (immediate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasm chronic cases may develop pulmonary emphysema.

Characteristics: Type I allergies (hay fever, asthma)

Wind disperses the powdery brown teliospores of smut. Smut’s do not usually grow indoors. They are parasitic plant pathogens that require a living host for the completion of their life cycle. Smut teliospores cannot easily be distinguished from the myxomycetes and certain species of Periconia.

Reported to be allergenic.

Can cause sporotrichosis. Usually only in populations which immune compromised.

Reported to be allergenic. See also Sporothrix sp. as it is some tazonomic confusion between these two genera. This genera does not cause sprotrichosis.

Characteristics: Allergenic, Toxigenic, Pathogenic

Description: Several strains of the fungus (S.atra, S.chartarum and S.alternansare synonymous) may produce a trichothecene mycotoxin, Satratoxin H, which is poisonous by inhalation. The toxins are present on the fungal spores. It is a slow growing fungus on media. It does not compete well with other rapidly growing fungi. The dark colored fungi grows on building material with high cellulose content and low nitrogen content. Areas subject to temperature fluctuations with relative humidity above 555 are ideal for toxin production. The organism is rarely found in outdoor samples. It is usually difficult to find in indoor air samples unless it is physically disturbed or if there is speculation, a drop in the relative humidity. The spores are in a gelatinous mass. The spores will die readily after release. The dead spores are still allergenic and toxigenic.

Individuals with chronic exposure to the toxin produced by the fungus reported cold and flu symptoms, sore throats, diarrhea, headaches, fatigue, dermatitis, intermittent local hair loss and generalized malaise. The toxins produced by the fungus will suppress the immune system affecting the lymphoid tissue and the bone marrow. Animals injected with the toxin from the fungus exhibited the following symptoms: necrosis and hemorrhage within the brain, thymus, spleen, intestine, lung, heart, lymph node, liver and kidney. Affects by absorption of the toxin in the human lung are known as pneumomycosis. Percutaneous absorption has caused mild symptoms. Toxicologically, stachybotrys can produce extremely potent trichothecene poisons, as evidenced by one-time lethal doses in mice (LD50) as low as 1.0 to 7.0 mg/kg, depending on the toxin and the exposure route. Depression of immune response, and hemorrhage in target organs are characteristic for animals exposed experimentally and in field exposures (Ueno, 1980; Jakab et al., 1994).

Some of these difficulties derive from the nature of the organisms and the toxic products they produce and varying susceptibilities among those exposed. Others relate to problems common to retrospective case control studies. Some of the difficulties in making the connection between toxic mold exposures and illness are discussed below.

Johanning, (1996) in an epidemiological and immunological investigation, reports on the health status of office workers after exposure to aerosols containing S. chartarum. Intensity and duration of exposure was related to illness. Statistically significant differences for more exposed groups were increased lower respiratory symptoms, dermatological, eye and constitutional symptoms, chronic fatigue, and allergy history. Duration of employment was associated with upper respiratory, skin and central nervous system disorders. A trend for frequent upper respiratory infections, fungal or yeast infections, and urinary tract infections was also observed. Abnormal findings for components of the immune system were quantified, and it was concluded that higher and longer indoor exposure to S. chartarum results in immune modulation and even slight immune suppression, a finding that supports the observation of more frequent infections.

Stachybotrys is a member of the Deuteromycetes, order Moniliales, family Dematiaceae, and is common on plant debris and in soil. Mycotoxins and other biologically active compounds produced by stachybotrys are the reason why this fungus is of such great concern to human health. Stachybotrys chartarum is one of many molds that are capable of producing one or more mycotoxins (chemicals produced by molds that may be able to cause symptoms or illness and death in people). Mycotoxin poisoning by this fungus is referred to as stachybotryotoxicosis.

Stachybotrys chartarum produces the following types of macrocyclic tricothecenes: verrucarin J, roridin E, satratoxin F, G & H, sporidesmin G, trichoverrols; cyclosporins, stachybotryolactone, trichoverrols, and trichoverrins. Macrocyclic trichothecenes are highly toxic compounds. The severity of mycotoxicosis was related to the duration of consumption of toxic grain. Such severe trichothecene mycotoxicoses, the consequence of continuous ingestion of toxins, have not been recorded since earlier outbreaks. In several cases, trichothecene mycotoxicosis was caused by a single ingestion of bread containing toxic flour or rice. In experimental animals, trichothecenes are 40 times more toxic when inhaled than when given orally.

The satratoxins are generally produced in greater amounts than the other trichothecenes, but all compounds are produced in low quantities. They occur in all parts of the fungus. One isolate was reported to contain about 15 ppm trichothecene in the conidia. The difficulty in obtaining, identifying and purifying these toxins has slowed extensive studies on their biological activity.

In addition, the fungus produces 9-phenylspirodrimanes (spirolactones and spirolactams) and yclosporine which are potent immunosuppressive agents. Jarvis et al. (1995) suggested that the combination of trichothecenes and these immunosuppressive agents may be responsible for the observed high toxicity of this fungus.

Three articles describing different aspects of an investigation of acute pulmonary hemorrhage in infants, including death of one infant, have been published recently, as well as a CDC evaluation of the investigation (Montaña et al., 1997; Etzel et al., 1998; Jarvis et al., 1998; MMWR, 2000; CDC, 1999). The infants in the Cleveland outbreak were reported with pulmonary hemosiderosis, a sign of an uncommon of lung disease that involves pulmonary hemorrhage. Stachybotrys chartarum was shown to have an association with acute pulmonary bleeding. Additional studies are needed to confirm association and establish causality.

Animal experiments in which rats and mice were exposed intranasally and intratracheally to toxic strains of S. chartarum, demonstrated acute pulmonary hemorrhage (Nikkulin et al. 1996).

A number of case studies have been more recently published. One involving an infant with pulmonary hemorrhage in Kansas, reported significantly elevated spore counts of Aspergillus and Penicillium in the patient’s bedroom and in the attic of the home. Stachybotrys spores were also found in the air of the bedroom, and the source of the spores tested highly toxigenic (Flappan et al., 1999). In another case study in Houston, stachybotrys was isolated from bronchopulmonary lavage fluid of a child with pulmonary hemorrhage. (Elidemir et al., 1999), as well as recovered from his water damaged-home. The patient recovered upon removal and stayed well after return to a cleaned home. Another case study reported pulmonary hemorrhage in an infant during induction of general anesthesia. The infant was found to have been exposed to stachybotrys prior to the anesthetic procedure (Tripi et al., 2000). Still another case describes pulmonary hemorrhage in an infant whose home contained toxigenic species of Penicillium and Trichoderma (a mold producing trichothecene poisons similar to the ones produced by S. chartarum) as well as tobacco smoke (Novotny and Dixit, 2000).

Finding stachybotrys within a building does not necessarily mean that occupants have been exposed either to allergens (pieces of the fungus or spores that can cause allergic symptoms in people prone to allergies) or toxins produced by this fungus. Laboratory studies indicate that molds such as stachybotrys that have the ability to produce toxins do not always do so. Whether a mold produces a toxin while growing in a building may depend on what the mold is growing on, conditions such as temperature, food, pH, humidity or other unknown factors. When mycotoxins are present, they occur on spores and the small mold fragments that may be released into the air.

Much of what is currently known about exposure to mycotoxins has emerged from veterinary science. The toxic effects from mycotoxins produced by stachybotrys chartarum were first reported in the 1920s in Russia, when researchers reported severe morbidity and mortality in cattle and horses that ingested hay contaminated with this mold. Clinical observations included severe skin and mucous membrane inflammation, bleeding disorders, diarrhea, and upper and lower respiratory tract disorders.

Of particular concern is the threat that humans will inhale and ingest these toxic spores. One vague example are Yellow Rain attacks in Southeast Asia during the 1970s that were associated with the use of aerosolized trichothecenes. The toxins are often present on the fungal spores. Recent experimental animal studies have reported severe intra-alveolar, bronchiolar, and interstitial inflammation in mice that were exposed via an intranasal route with trichothecenes.

In contrast to toxicity from direct inhalation of stachybotrys spores, simulated environmental conditions with extensive surface growth of toxigenic stachybotrys and high air flow have not produced significant pulmonary toxicity in exposed mice. This observation may be related to the physical properties of stachybotrys; it produces spores in a slimy mass that are unlikely to become airborne without dry conditions. In addition, the production of mycotoxin by stachybotrys is dependent upon the environmental conditions of its growth. On some building materials and growth substrates, stachybotrys has not demonstrated biologic toxicity or mycotoxin production.

In laboratory animals, acute exposure to large amounts of trichothecene toxins resulting in a rapid release of stored white blood cells into circulation, while repeated or chronic exposure destroys granulocytic precursor cells in bone marrow leading to white cell depletion. Among the reported cellular effects are: mitogen B/T lymphocyte blastogenesis suppression, decrease of IgM, IgG, IgA; impaired macrophage activity and migration-chemotaxis; broad immunosuppressive effects on the cellular and humoral-mediated immune response leading to secondary infections; immunomodulation leading to spontaneous antibody increase and immunosuppressive effects in human peripheral blood lymphocytes.

Characteristics: It is a known allergen. Shares allergens with Alternaria.

It has approximately 6 species. It is found in soil, wood, decaying vegetation. Some species found on leaves and are plant pathogens. Growth indoors is rare. Stemphylium is distinctive, and not easily confused with other genera, although young spores or spore fragments may be confused with other pigmented muiform spores such as Ulocladium, Alternaria or Pithomyces. It is distinctive and readily identifiable on tape lifts. Although Stemphylium is rarely found growing indoors, it may be seen in dust as part of the normal influx of outdoor particles.

Can cause a respiratory infection characterized by a solid fungal ball.


Characteristics: Type I allergies (hay fever, asthma).

Allergen: Type I allergies (hay fever, asthma).

Potential Opportunist or Pathogen: No reports of human infection Potential Toxin Production: Torula herbarum was cytotoxic in screening tests performed by our laboratory.

Description: The nature of the toxin(s) is unknown.

Characteristics: The only reported human infections are two cases of keratitis (1922, 1965). No information is available regarding toxicity. Allergenicity has not been studied.

Trichocladium comprise a small proportion of the fungal biota. This genus is somewhat related to Torula. It may be identified on surfaces by tape lifts, and tease mounts from bulk samples. Certain species can be identified in air by culturable (Andersen) samples and certain other species by spore trap samples (spores of some species have distinctive morphology). One species in particular, Trichocladium uniseptatum, is found regularly on environmental surfaces, chiefly from wood. This organism does not grow on general fungal laboratory media and has been reported in times past as an “unknown brown spore type.” Recorded isolations of Trichocladium species include soil, wood, tubers of varioud plants, and pine needles.

It is commonly found in soil, dead trees, pine needles, and unglazed ceramics. It often will grow on other fungi. It produces antibiotics which are toxic to humans. It has been reported to be allergenic (7,17). It readily degrades cellulose.

Can cause ring worm, athlete’s foot, skin, nail, beard, and scalp (5, 6). Reported to be allergenic. Found on soil and skin.

Aw (water activity) 0.90. Conidia (spores) dimensions of 23 x 8-10 microns. Found in decomposing vegetation, soil, corn seeds, and in flour. The species Trichothecium roseum can produce a trichothecene toxin may be associated with disease in humans and other animals. Reported to be allergenic.

Reported to be allergenic.


Ulocladium: Characteristics: Major. Type I allergies (hay fever, asthma).

Ulocladium cross-reacts with Alternaria, adding to the allergenic burden of Alternaria-sensitive patients.
It is found in soil, dung, paint, grasses, fibers, wood, decaying plant material, paper, and textiles. It’s mode of distribution is dry spore and wind. It’s growth indoors is widespread. It is found on gypsum board, paper, paint, tapestries, jute, other straw materials. Ulocladium has a high water requirement. With spore trap recognition it has distinctive brown spores. Young spores or spore fragments may be confused with Alternaria, Pithomyces, and others, although Alternaria usually has shades of olive green pigment.


Conidia (spores) dimensions 2.3-10 x 1-2.6 microns. Found on decaying vegetation, on straw, soil, and arthropods. A rare cause of corneal infections.


Has an Aw (water activity) of 0.75. Conidia (spores) dimensions 2.5-3.5 microns. Found in sugary foods, salted meats, dairy products, textiles, soil, hay, and fruits.


Various yeasts are commonly identified on air samples. Some yeasts reported to be allergenic. They may cause problems if a person has had previous exposure and developed hypersensitivity. Yeasts may be allergenic to susceptible individuals when present in sufficient concentrations.

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