Fungal Infections

Species/common name:

Aspergillus flavus

Teleomorph: None

Natural habitat

Common contaminant of food and soil.

Geography

Worldwide distribution.

Frequency

Second most common cause of aspergillosis after Aspergillus fumigatus and increasingly being isolated. More common than A. fumigatus in air for unknown reasons.

Diseases

Aspergillosis refers to infection by any of the Aspergillus species. Infection can be limited to the lungs (pulmonary) or spread throughout the body (disseminated Aspergillosis) in more severe cases. Allergenicity of A. flavus is notable but still unclear. A. flavus is most often associated with:

1)      Chronic cavitary pulmonary aspergillosis;

2)      Allergic bronchopulmonary aspergillosis;

3)      Allergic fungal sinusitis and sinus aspergilloma;

4)      Keratitis and endophthalmitis;

5)      Cutaneous and wound infections;

6)      Endocarditis, pericarditis and CNS infections

7)      Osteoarticular infections

8)      Urinary tract infections

Culture peculiarities

Velvet-like; yellow to green or brown mould with a gold to red-brown reverse. In microscopy, the conidial heads are radiate. Conidiogenous cells are uni- or biseriate and conidia echinulate.

Antifungal resistance (intrinsic and acquired)

Acquired amphotericin B resistance becoming increasingly prevalent. Mostly susceptible to echinocandins and triazole antifungals but some resistance has been noted; however, the overall percentage of isolates resistant to these drugs remains low.

Biosafety level 2

This fungal species may be managed in a laboratory with safety containment level 2.

Industrial use:

Study organism for aflatoxin (potent carcinogen found in food) and other mycotoxins. Biocontrol organism for crops: genetic manipulation of an A. flavus strain in which the aflatoxin pathway has been knocked out and now spread on crops, successfully competing with natural strains that do produce aflatoxin. Very closely related to Aspergillus oryzae which is extensively used in the Far East for the making of soy sauce, miso and other fermented foods.

Images

Typical appearance of the conidial head of A. flavus stained with lactophenol
cotton blue, with the green appearance of the spores apparent.


A. flavus colony green colouration on Sabouraud dextrose agar.

Appearance of A. flavus within the cornea of a patients with fungal keratitis,
stained with lactophenol cotton blue (Dr Philip Thomas, Tiruchirappalli).

 

Take action today

Educate

Recognise & treat fungal
infections: See opportunities for
learning.

Spread
the word

Help us change as many
lives as possible by
sharing this site!