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Introduction Aspergillus flavus on Czapek Dox agar

Aspergillus flavus growth on Czapek Dox agar is after 3 days of incubation at 25°C. Colony characteristics are showing granular flat, often with radial grooves, initially yellow but quickly becoming bright to dark yellow-green with age. It is a saprotrophic and pathogenic fungus with a cosmopolitan distribution and its colonization of cereal grains, legumes, and tree nuts. Its specific name flavus derives from the Latin meaning yellow, a reference to the frequently observed color of the spores.  Aspergillus flavus is also an opportunistic human pathogen, causing aspergillosis in immunocompromised hosts.

Czapek-Dox Agar uses in cultivating fungi capable of using inorganic nitrogen. It is a modification of the Czapek and Dox formula prepared according to Thom and Church. The medium contains sucrose as the sole source of carbon and nitrate as the only inorganic source of nitrogen. The medium is useful in a variety of microbiological procedures, including fungi and mildew resistance tests and soil microbiology testing. It produces luxuriant growth of most saprophytic Aspergilli causing the organisms to produce characteristic mycelia and conidia and recommended in Standard Methods for the Examination of Water and Wastewater for the isolation of Aspergillus species, Penicillium species, Paecilomyces species, and other types of fungi with similar physiological requirements.

Composition of Czapek-Dox Agar

• Sucrose:  30.0 gm
• Sucrose:  30.0 gm
• Sodium Nitrate: 2.0 gm
• Dipotassium Phosphate:  1.0 gm
• Magnesium Sulfate:  0.5 gm
• Potassium Chloride: 0.5 gm
• Ferrous Sulfate:  0.01 gm
• Agar : 15.0 gm
• Distilled water: 1000 ml

Isolation of Aspergillus flavus  

A patient with chronic suppurative otitis media (CSOM) with active ear discharge from 3 months. Specimen inoculated into this Czapek-Dox agar fungal medium and growth of Aspergillus flavus found. Potassium hydroxide (KOH) preparation was also positive due to having fungal structures.

Treatment of Isolation of Aspergillus flavus  

The patient gets cured after treating with an antifungal drug, itraconazole. Aspergillus flavus has a worldwide distribution and is also a recognized pathogen of humans. It comes under risk group -2 organism.

Further Readings

1. Medical Mycology. Editors:  Emmons and Binford, 2nd ed 1970, Publisher Lea and Febiger, Philadelphia.
2. Rippon’s JW: Medical Microbiology. The pathogenic fungi and the Pathogenic Actinomycetes. 3^rd ed 1988 Publisher WB Saunder co, Philadelphia.
3. Clinical Microbiology Procedure Handbook Vol. I & II, Chief in editor H.D. Isenberg, Albert Einstein College of Medicine, New York, Publisher ASM (American Society for Microbiology), Washington DC.
4. A Textbook of Medical Mycology. Editor: Jagdish Chander.  Publication Mehata, India.
5.  Practical Laboratory Mycology. Editors: Koneman E.W. and G.D. Roberts, 3rd ed 1985, Publisher Williams and Wilkins, Baltimore.
6. Topley & Wilsons Medical Mycology. Editors: M.T. Parker & L.H. Collier, 8th ed 1990, Publisher Edward Arnold publication, London.
7. Textbook of Diagnostic Microbiology. Editors: Connie R. Mahon, Donald G. Lehman & George Manuselis, 3rd edition2007, Publisher Elsevier.
8. Mackie and Mc Cartney Practical Medical Microbiology. Editors: J.G. Colle, A.G. Fraser, B.P. Marmion, A. Simmous, 4th ed, Publisher Churchill Living Stone, New York, Melborne, Sans Franscisco 1996.
9. Bailey & Scott’s Diagnostic Microbiology. Editors: Bettey A. Forbes, Daniel F. Sahm & Alice S. Weissfeld, 12th ed 2007, Publisher Elsevier.