Aspergillus spp.: Rapidly growing fungi that produce pigmented colonies that are some shade of green, yellow, brown, or black within ten days, when incubated at 25C (77F). It is very common worldwide. It can be isolated from air, plants, foodstuffs, soil, sand beaches, caves and mines, activated sludge, mangrove swamps, fresh water, compost, animal dung, silage, fodder, and cotton fabrics in the tropics. The genus Aspergillus includes over 185 species. Around 20 species have so far been reported as causative agents of opportunistic infections in man.
Clinical Relevance:
Some species are thermotolerent. Some species are allergenic and other species produce powerful mycotoxins. They are one of the most common causes of systemic fungal disease in humans and animals causing primarily acute or chronic respiratory tract infections.Aspergillus spp. are well-known to play a role in three different clinical settings in man: (i) opportunistic infections; (ii) allergic states; and (iii) toxicoses. Immunosuppression is the major factor predisposing to development of opportunistic infections. These infections may present in a wide spectrum, varying from local involvement to dissemination and as a whole called aspergillosis. Among all filamentous fungi, Aspergillus is in general the most commonly isolated one in invasive infections. It is the second most commonly recovered fungus in opportunistic mycoses following Candida.
Almost any organ or system in the human body may be involved. Onychomycosis, sinusitis, cerebral aspergillosis, meningitis, endocarditis, myocarditis, pulmonary aspergillosis, osteomyelitis, otomycosis, endophthalmitis, cutaneous aspergillosis, hepatosplenic aspergillosis, as well as Aspergillus fungemia, and disseminated aspergillosis may develop Nosocomial occurrence of aspergillosis due to catheters and other devices is also likely. Construction in hospital environments constitutes a major risk for development of aspergillosis particularly in neutropenic patients.
Aspergillus spp. may also be local colonizers in previously developed lung cavities due to tuberculosis, sarcoidosis, bronchiectasis, pneumoconiosis, ankylosing spondylitis or neoplasms, presenting as a distinct clinical entity, called aspergilloma. Aspergilloma may also occur in kidneys.
