Pure
Air Control Services and the Environmental Diagnostics Laboratory are pleased
to introduce "Under the Scope", a new section of the
IEQ REVIEW.
There are over 100,000 species of fungi. Many fungi are good and useful (edible
mushrooms would be an example of these) while some cause problems (some fungi
can injure plants and humans). Every week the IEQ Review will describe a
specific microorganism, its morphological origin and potential health
effects. If you would like to know about a specific organism and/or would
like it published in The IEQ Review please email Dr. Rajiv Sahay with
the Environmental Diagnostics Laboratory (EDL) at Pure Air Control
Services
laboratory@pureaircontrols.com
This week we will cover ...
Alternaria
alternata
Alternaria sp.: A
rapidly growing fungus that produces a grayish-white colony that becomes
greenish-black within five days, when incubated at 25C (77F). The hyphae,
conidiophores, and conidia are pigmented olivaceous-brown (dematiaceous). It is
found worldwide and is very common. It can be isolated from air, plants
(including causing "blackspot of roses"), foodstuffs, soil, and
textiles. While
Alternaria chartarum,
Alternaria dianthicola,
Alternaria geophila,
Alternaria infectoria,
Alternaria
stemphyloides, and
Alternaria teunissima are among the other
Alternaria
spp. isolated from infections, some
Alternaria strains reported as
causative agents remain unspecified.
Clinical relavance:
Alternaria sp. can be an opportunist human pathogen causing a
hypersensitivity pneumonitis (woodworker's lung disease), and an immediate-type
hypersensitivity-type 1 (IgE-mediated) extrinic asthma and disease that is very
common in individuals with atopic disease. They are one of the causative
agents of phaeohypomycosis. Cases of onychomycosis, sinusitis, ulcerated
cutaneous infections, and keratitis, as well as visceral infections and
osteomyelitis due to
Alternaria have been reported. In immunocompetent
patients,
Alternaria colonizes the paranasal sinuses, leading to chronic
hypertrophic sinusitis. In immunocompromised patients the colonization may end
up with development of invasive disease. It is among the causative agents
of otitis media in agricultural field workers.
Since
Alternaria species are cosmopolitan and ubiquitous in nature, they
are also common laboratory contaminants. Thus, their isolation in culture
requires cautious evaluation.
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