Commonly Found Indoor Molds

Acremonium   naturally found in soils, decaying organic matter and plat debris.  Can be found in food and indoor environments.  A common allergen.  Can produce a trichothecene mycotoxins and volatile organic compounds.

Agrocybe/Coprinus This genus is a basidiomycetous mold. 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

Alternaria        A common saprobe found on decaying wood, decaying plants, food, spoil and outdoor air.  Some species are plant pathogens.  Indoors, it can be found in house dust, carpets, damp areas around showers and windows frames and anywhere condensation occurs.  Because of its abundance and ubiquity, Alternaria is one of the most important fungal allergens and is recognized as the chief fungal cause of hay fever.  Infection is extremely rare.

Arthrinium   is a cosmopolitan filamentous fungus isolated from plant debris and soil. There are no infections so far reported due to Arthrinium in humans or animals. Since Arthrinium is cosmopolitan in nature, it is an occasional laboratory contaminant.

Ascomycete     constitute the largest class of fungi characterized by the production of sexual spores in structures call asci.  This includes plant pathogens, saprobes and decomposers.  With a few exceptions, most Ascomycetes do not grow in buildings and are seldom agents of wood rot.  Ascomycetes are the perfect stages of molds like Aspergillus and Penicillium.  At high levels, Ascomycete spores may cause allergies.

Since most Ascomycetes are plant pathogens, ascospores are common during the growing season of plants and are rare during winter, such as those of the Ascomycetes genera: Daldinia, Hypoxylon, Paraphaeospaeria, Phaeosphaeria and Leptosphaeria.

Aspergillus   Reported to be allergenic. Members of this 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.

Aureobasidium A Common saprobe frequently isolated from soil, plant surfaces, seeds, grains, fruits and other food, human skin and nails.  Common indoors in humid areas such as bathrooms, kitchens, poorly maintained HVAC systems and window frames.  Allergies to Aureobasidium are common, but infections are rarely reported.

Basidiomycetes    A class of fungi characterized by spores formed on basidia.  Included the mushrooms, toadstools, wood bracket fungi and puffballs.  Some species are edible, such as Agaricus bisporus, the commercially cultivated mushrooms.  A few species cause wood brown rot, white rot and dry rot in buildings.

Bipolaris The genus Bipolaris is cosmopolitan in nature and can be isolated from plant debris and soil.  It contains about 45 species, most of which are subtropical and tropical plant parasites. However, a few species are capable of causing disease in humans.

Botrytis is a filamentous fungus isolated from decaying plants. No infections due to Botrytis have been reported in humans or animals. It may act as a facultative pathogen in plants and is commonly considered as a contaminant

Cercospora This genus is a mold that lacks a known sexual state and thus belongs to the Fungi Imperfecti.

Chaetomium A common fungus in soils, dung, decaying organic matter, seeds and wood or other cellulose-containing materials.  Can be found indoors in water-damaged buildings on sheet rock, wall paper and other paper products.  It is a common cause of food spoilage.  In some species it is allergenic, but rarely causes human infections.

Chrysosporium A common soil saprobe occasionally isolated from human or animal skin and nail.  Chrysosporium inops is xerophilic and occurs in food.

Cladosporium is widely distributed as plant pathogens and saprobes.  It is the most frequently found fungus in outdoor air.  Indoors, it usually occurs at low concentrations in damp or humid areas, but may be found in high concentrations in water-damaged building materials.  Its ability to sporulate heavily and to get airborne makes it an important fungal allergen.  Frequently isolated as a contaminant in foods.  Only occasionally associated with disease in humans; one species can cause chronic subcutaneous infection.

Curvularia A common saprobe found in soils, plants, cereals and cellulosic materials such as paper and archives.  Some species are plant pathogens,  Can Be found indoors.  It is allergenic and may cause infections in immunocompromised individuals.

Epicoccum      A cosmopolitan saprobe isolated from air, soil, grain, seeds, textiles, paper products and food materials.  Can be a plant pathogen and is a common cause of leaf spots of various plants.  Can be found in indoor environments, where it can grow under conditions of low humidity.  It is a known allergen and is occasionally isolated from human skin and sputum.

Eurotium Can be found in stored food, fruit juices, grains, nuts, milled rice, spices, meat products and peas.  Also commonly occurs in indoor environments.  Eurotium harboriorum may case keratitis and indigestion in man.

Exophiala is a dematiaceous fungus widely distributed in soil, plants, water, and decaying wood material. As well as being a saprophyte in nature, it is the causative agent of various human infections.

Fusarium 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 potent trichothecene toxins. The trichothecene (scirpene) toxin targets, the following systems: circulatory, alimentary, skin and nervous. Produces vomitoxin on grains during unusually damp growing conditions. Symptoms may occur either through ingestion of contaminated grains 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

Ganoderma  Large very hard, woody bracket fungus that grows on living and dead trees.  Some species are common on oaks, chestnuts and conifers such as hemlocks, spruces and pines. Many species are being investigated for possible medicinal uses

Geotrichum   Geotrichum is a yeast found worldwide in soil, water, air, and sewage, as well as in plants, cereals, and dairy products. It is also found in normal human flora and is isolated from sputum and feces.  The genus Geotrichum includes several species. The most common one is Geotrichum candidum. Geotrichum clavatum and Geotrichum fici are among other Geotrichum species.   Geotrichum fici has an intense smell resembling that of pineapple.  As well as being a colonizer of the intestinal tract, Geotrichum spp. may cause opportunistic infections in immunocompromised host and these infections are referred to as geotrichosis. The infections are usually acquired via ingestion or inhalation. Bronchial and pulmonary as well as disseminated infections and fungemia due to Geotrichum have been reported. It has also been isolated from infections resulting from trauma.

Apart from its clinical significance, there are very recent claims on environmental damages that Geotrichum might have caused. It has been blamed for destroying the aluminium and data-storing polycarbonate resin that are found in the structure of compact discs. This in turn led to discoloration of the disc, with the disc becoming partly transparent. The exact role of Geotrichum in this destruction process requires confirmation.

Gliocladium is a mitosporic filamentous fungus which is widely distributed in soil and decaying vegetation.  It is commonly considered as a contaminant.

Graphium is a filamentous fungus found in soil and plant material. While Graphium may be isolated as an occasional contaminant, its telemorphs, Petriella, Pseudallescheria, and Ceratocystis may cause diseases. Most isolates of Graphium isolated in the clinical laboratory are synanamorphic forms of Pseudallescheria boydii or secondary forms with Scedosporium apiospermum.

Mucor is a filamentous fungus found in soil, plants, decaying fruits and vegetables. As well as being ubiquitous in nature and a common laboratory contaminant, Mucor spp. may cause infections in man, frogs, amphibians, cattle, and swine. Most of the Mucor spp. are unable to grow at 37°C and the strains isolated from human infections are usually one of the few thermotolerant Mucor spp..

Myxomycete  is an ancient form of slime mold.  Not much is presently known about Myxomycete.  It is often found on decaying wood or organic material

Ophiostoma This genus is an ascomycetous mold

Paecilomyces A common saprobe found on dead plant and compost. Some species are insect parasites.  Can cause food decomposition.  It is rarely a human pathogen, but can cause infection in animals.  However, some species are emerging as causative agents of disease in immunocompromised individuals.

Penicillium A wide number of organisms have placed in this genera. Identification to species is difficult. Often found in aerosol samples. Commonly found in soil, food, cellulose and grains. It is also found in paint and compost piles. It may cause hypersensitivity pneumonitis, allergic alveolitis in susceptible individuals. It is reported to be allergenic (skin). It is commonly found in carpet, wall paper, and in interior fiberglass duct insulation. Some species can produce mycotoxins. Common cause of extrinsic asthma (immeadiate-type hypersensitivity: type I). Acute symptoms include edema and bronchiospasms, chronic cases may develop pulmonary emphysema.

Periconia This genus is a mould that lacks a known sexual state and thus belongs to the Fungi Imperfecti. It is generally classified as a dematiaceous (dark-walled) fungus.

Phialophora occurs in nature as a soft rot fungus on wood, which and often cause a blue stain.  Can cause diseases in immunocompromised individuals.

Phoma    A common indoor air allergen. The species are isolated from soil and associated plants (particularly potatoes). Produces pink and purple spots on painted walls. It will grow on butter, paint cement and rubber. It may cause phaeohyphomycosis a systematic or subcutaneous disease

Pithomyces  This genus is a mold that lacks a known sexual state and thus belongs to the Fungi Imperfecti. It is generally classified as a dematiaceous (dark-walled) fungus. Grows on dead grass in pastures. Causes facial eczema in ruminants

Rhizopus   Frequently isolated from soil and agricultural products, such as cereals and vegetables.  Can cause infection in immunocompromised, malnourished or severely burned individuals.

Rhodotorula   A reddish yeast frequently isolated from air, soil, water, fruit juice, dairy products and other substances.  Typically found as a saprobe in moist environments indoors such as carpeting, cooling coils, water tanks, humidifiers and drain pipes.  Reported to be allergenic.  Has colonized terminally ill patients.

Rust Obligate parasitic fungi, which belong to Tellomycetes – Uredinales that cause plant disease.

Smut  Obligate parasites and pathogens of plants that cause smut on various plant pars such as Silene anthers, corn kernels, onion bulbs and rice grains.

Sporobolomyces can be commonly detected in air samples.  Frequently encountered indoors in water tanks, humidifiers, drain pans, etc.

Sporothrix  Isolated from soil, live or dead plants and peat moss.  Sporothrix schenckii is an agent of human sporotrichosis, cutaneous infection and ocular mycosis, usually in immunocompromised people.

Stachybotrys Several strains of this fungus (S. atra, S. chartarum and S. alternans are synonymous) may produce a trichothecene mycotoxin- Satratoxin H - which is a poisonous by inhalation. The toxins are present on the fungal spores. This 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 a high cellulose content and a low nitrogen content. Areas with relative humidities above 55% and are subject to temperature fluctuations are ideal for toxin production.

Individuals with chronic exposure to the toxin produced by this fungus reported cold and flu symptoms, sore throats, diarrhea, headaches, fatigue, dermatitis, intermittent local hair loss  and generalized malaise. The toxins produced by this fungus will suppress the immune system affecting the lymphoid tissue and the bone marrow. Animals injected with the toxin from this 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.

This 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. Appropriate media for the growth of this organism will have a high cellulose content and a low nitrogen content. The spores will die readily after release. The dead spores are still allergenic and toxigenic. Percutaneous absorption has caused mild symptoms.

There is controversy about toxigenic effects through inhalation of spores or mycelia

Tetraploa This genus is a mold that lacks a known sexual state and thus belongs to the Fungi Imperfecti.

Torula: A very common hyphomycete on all kinds of dead, decaying herbaceous stems, especially in humid conditions. It forms dense, olive green to black areas of "mold", the colour that of the abundant conidia. It is reported to be allergenic.

Trichoderma    Very common especially in soil and decaying wood, dead leaves, fallen timber, compost heaps and activated sludge.  Can be found indoors in water damaged buildings.  Has occasionally bee associated with disease in immunocompromised individuals.

Tritirachium A saprobe commonly isolated from decaying plant materials.  Easily gets airborne.  Can cause corneal ulcers.

Ulocladium      Found as a saprobe in soil, plant materials, rotten wood, appear, textiles and cellulose materials.  Frequently collected in air and dust samples.  Can grow indoors on water damaged building materials.  Has not been associated with disease in humans, but can be very allergenic.

Verticillium is a widely distributed filamentous fungus that inhabits decaying vegetation and soil. Some Verticillium species may be pathogenic to arthropods, plants, and other fungi. It is commonly considered as a contaminant. Verticillium may very rarely cause human disease.

Wallemia  A very xerophilic fungus that has been isolated from soil, air, hay, textiles and food such as jam, salted fish and mild products.  Can cause allergies.

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

Zygomycete is not the name of particular fungus, but rather the name of a Class of fungi. This Class includes three Orders (Mucorales, Mortierellales, and Entomophthorales). These Orders in turn contain a number of specific fungi.


Marc & Robin Leftwich

At the Susan G. Komen Breast Cancer Mother's Day Walk