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 geophilia, 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.
 
 

Alternaria species                                                           

 
 
 
 Alternaria geophilia



Health Significance

Alternaria sp.
It 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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