Date: 26 November 2013
Aspergillus fumigatus Fresen
Copyright:
© Fungal Research Trust
Notes:
Colonies on CYA 40-60 mm diam, plane or lightly wrinkled, low, dense and velutinous or with a sparse, floccose overgrowth; mycelium inconspicuous, white; conidial heads borne in a continuous, densely packed layer, Greyish Turquoise to Dark Turquoise (24-25E-F5); clear exudate sometimes produced in small amounts; reverse pale or greenish. Colonies on MEA 40-60 mm diam, similar to those on CYA but less dense and with conidia in duller colours (24-25E-F3); reverse uncoloured or greyish. Colonies on G25N less than 10 mm diam, sometimes only germination, of white mycelium. No growth at 5°C. At 37°C, colonies covering the available area, i.e. a whole Petri dish in 2 days from a single point inoculum, of similar appearance to those on CYA at 25°C, but with conidial columns longer and conidia darker, greenish grey to pure grey.
Conidiophores borne from surface hyphae, stipes 200-400 µm long, sometimes sinuous, with colourless, thin, smooth walls, enlarging gradually into pyriform vesicles; vesicles 20-30 µm diam, fertile over half or more of the enlarged area, bearing phialides only, the lateral ones characteristically bent so that the tips are approximately parallel to the stipe axis; phialides crowded, 6-8 µm long; conidia spherical to subspheroidal, 2.5-3.0 µm diam, with finely roughened or spinose walls, forming radiate heads at first, then well defined columns of conidia.
Distinctive features
This distinctive species can be recognised in the unopened Petri dish by its broad, velutinous, bluish colonies bearing characteristic, well defined columns of conidia. Growth at 37°C is exceptionally rapid. Conidial heads are also diagnostic: pyriform vesicles bear crowded phialides which bend to be roughly parallel to the stipe axis. Care should be exercised in handling cultures of this species.
Images library
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Aspergillus flavus and Aspergillus parasiticus can produce aflatoxins are generally known as storage fungi, but they can also cause ear rots in the field. These species are observed as a gray-green, powdery molds and they can be detected in corn because they produce compounds that are fluorescent under black light.
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Histopathology of the jejenum showing necrosis and hyphae consistent with Aspergillus
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Further image details
Image A. Multiple small lesions at both ends of the cordae tendinae in this patient who died of disseminated aspergillosis. He was a previously well 70 year old man who developed pneumonia on holiday, required artificial ventilation and died with a rapidly progressive cavitating pneumonia. Autopsy showed disseminated aspergillosis.
Image B. Another lesion in pt DB, that histologically showed a mass of hyphae and fibrin.
Image C. Large destructive lesion on the mitral valve in patient DB.
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The patient was a 610 g twin male born by spontaneous normal vaginal delivery at 23 weeks and 4 days gestation. He was started on benzyl penicillin and gentamicin for sepsis. On day 3, he developed metabolic acidosis, hyponatremia, anemia, thrombocytopenia and jaundice and his antibiotics were changed to vancomycin, cefotaxime and fluconazole.
On day 10, multiple circular skin papules with white eschars were noted on his back (Figure A). A full septic screen was repeated including skin scraping and biopsy for urgent microscopy and culture. Microscopy of skin scrapes revealed fungal elements including hyphae and fruiting heads suggestive of Aspergillus spp (Figure B). Lipid amphotericin B was commenced and fluconazole was stopped. Skin scrapings on culture grew Aspergillus fumigatus. A diagnosis of primary cutaneous aspergillosis was made. The patient responded to oral posaconazole 6mg/kg/8 hourly. All lesions disappeared after 44 days and he continued with posaconazole until day 60.
Published case at Langan et al Pediatr Dermatol 2010 Jul-Aug 27 (4) 403-4
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