Alternaria species are plant pathogens and common allergens that are abundant in both indoor and outdoor environments.
Habitat: In nature, it is commonly found in soil, seeds and plants and is known as one of the major plant pathogens. Indoors it is commonly found in water damaged buildings growing on carpets, textiles, drywall and horizontal surfaces such as window frames.
Microscopic Appearance: Alternaria is most often formed in chains. They are typically club-shaped and are highly septate, with divisions in both vertical and horizontal planes. The spore surfaces are usually smooth.
Macroscopic Appearance: Species produce olive-green to brown or black colonies and the reverse color on MEA and SAB agar is brown to black.
Health Effects: A common allergen and has been associated with hypersensitivity pneumonitis. It may be an agent of onychomycosis, cutaneous infection and chronic sinusitis, principally in the immunocompromised patients. Alternaria is capable of producing toxic metabolites which may be associated with disease in humans or animals. Alternaria has a unique group of mycotoxins, including alternariols, altenuenes, altertoxins, tenuazonic acid and AAL toxins.