What is Stachybotrys?

Definition

The pathogen
Stachybotrys is a mold that grows on wet cellulose-containing
materials. Stachybotrys produces a number of mycotoxins,
including several trichothecenes and a hemorrhagic protein called hemolysin.
Memnoniella
is a related fungus that has similar growth characteristics and
produces similar mycotoxins.

Natural Habitat and Features

Stachybotrys is a black or grey fungus (mold) with worldwide distribution. Stachybotrys grows on wet cellulose-containing material such as hay, leaves, paper, wood, wall board, textiles, rugs, drywall, and insulating materials. Stachybotrys is a fairly slow grower and may be overrun by other molds growing on cellulose-containing substrates.

Stachybotrys requires wet conditions to grow; however, Stachybotrys spores can remain dormant under dry conditions for several years and can resume active growth and mycotoxin production when water becomes available. The Stachybotrys mycotoxins can also retain their potency over several years without active Stachybotrys growth. Stachybotrys frequently grows in buildings that have been flooded by leaking pipes or toilets, rain infiltration, or natural disasters, including hurricanes.

Stachybotrys spores are often hard to grow in culture. Some studies have reported that cellulose-based media or cornmeal media is best for cultured Stachybotrys growth.

Stachybotrys spores are not as readily spread by air as are most mold spores. Several published studies have been unable to collect any airborne Stachybotrys spores, even though the buildings in question may be contaminated with many square meters of Stachybotrys growth. Relying on airborne samples only has led many indoor air investigators to falsely conclude that Stachybotrys was not growing in the structures under investigation. Because Stachybotrys spores are not readily dispersed in the air and are hard to grow in culture, all mold sampling studies that suspect Stachybotrys growth should take surface, tape, or building material samples from the building.

Pathogenicity and Clinical Significance

Localized Stachybotrys infections have been reported. Viable Stachybotrys was isolated from the lungs of a seven-year-old boy living in a water damaged farmhouse with heavy Stachybotrys growth. The boy, who experienced severe fatigue, chronic coughing, and lung hemorrhage, completely recovered after cleanup of his mold-infested home. Unpublished observations have reported Stachybotrys growth in nasal sinuses; however, the main health concerns are connected to the mycotoxins and allergens produced by Stachybotrys.

The Stachybotrys mycotoxins were first reported as contaminants of animal feed and human food. In the 1940’s, there were reports of domestic animals dying in the Soviet Union after eating Stachybotrys-infested hay. In later years, attention has been focused on humans who are exposed to high levels of Stachybotrys and its mycotoxins in indoor air and dust.

Stachybotrys produces a wide range of mycotoxins, including the
trichothecenes satratoxin, roridan, and deoxynivalenol. The amounts and types of
triochothecenes produced vary considerably depending on environmental conditions
and the Stachybotrys strain. The trichothecene mycotoxins damage
the immune and nervous systems, inhibit
protein
synthesis, and can cause vomiting. Animal studies have
reported that exposure to small amounts of trichothecenes can damage brain
cells.

Stachybotrys also produces a protein called hemolysin, which causes lung hemorrhage in nonhuman animals and may be linked to human lung hemorrhage. In the 1990’s, life-threatening lung hemorrhage was reported in ten infants in Cleveland, Ohio, who lived in water-damaged homes. Airborne levels of Stachybotrys, Aspergillus, and other molds were much higher in the homes of the infants with lung hemorrhage than in the control homes.

The allergens and mycotoxins from Stachybotrys can also worsen
asthma and nasal problems. Several studies have reported
that heavy indoor exposure to Stachybotrys and other molds is
associated with significantly poorer lung function and significant deficits in
many neuropsychiatric parameters, such as reaction times, color vision, memory,
concentration, grip strength, and vocabulary.

The ideal way to control Stachybotrys and its mycotoxins is to
prevent exposure to the mold. The best way to control
Stachybotrys growth is to prevent indoor water damage. All
cases of indoor water damage, standing water, or visible mold growth should be
cleaned within twenty-four hours to prevent growth of
Stachybotrys and other fungi and bacteria. For large cases of
water damages, one should contact a flood remediation company. Several guides are
available for mold remediation, including the U.S. Environmental Protection Agency’s
“Guide to Mold Remediation in Schools and Commercial Buildings” (available at
http://www.epa.gov/mold/mold_remediation.html).

Several studies have reported that clean up and water remediation of homes with heavy Stachybotrys growth are associated with less asthma, fatigue, and concentration and memory problems in the occupants of the contaminated home.

Drug Susceptibility

Because Stachybotrys does not appear to cause human infection, antifungal drugs are generally not used to treat persons who have been exposed to Stachybotrys. However, some studies have reported that the use of the bile-binding drug cholestryamine may be useful in speeding human excretion of trichothecene mycotoxins. Other research has suggested that eating a well-balanced diet that is high in antioxidants (vitamins A, C, and E, and l-carnitine and coenzyme Q10) can reduce the toxic effects of many mycotoxins.

Bibliography

Elidemir, Okam, et al. “Isolation of Stachybotrys from the Lung of a Child with Pulmonary Hemosiderosis.” Pediatrics 104 (1999): 964-966. A case report of viable Stachybotrys growing in the lungs of a seven-year-old boy.

Etzel, Ruth, et al. “Acute Pulmonary Hemorrhage in Infants Associated with Exposure to Stachybotrys atra and Other Fungi.” Archives of Pediatric and Adolescent Medicine 152 (1998): 757-762. This study reports on ten previously healthy infants who experienced sudden pulmonary hemorrhage. Airborne levels of Stachybotrys and Aspergillus were much higher in case homes versus control homes.

Kilburn, Kaye. “Neurobehavioral and Pulmonary Impairment in 105 Adults with Indoor Exposure to Molds Compared to 100 Exposed to Chemicals.” Toxicology and Industrial Health 25 (2009): 681-692. This paper provides thorough documentation that a group of 105 mold-exposed persons experienced significant deficits in lung function, reaction times, color vision, memory, grip strength, and vocabulary.

Samson, Robert, Ellen Hoesktra, and Jens Frisvad. Introduction to Food and Airborne Fungi. 7th ed. Utrecht, the Netherlands: Central Bureau for Fungal Cultures, 2004. This guide provides much information about Stachybotrys and many other indoor fungi. Includes useful identification keys, photographs, and diagrams.