Basidiobolus SpeciesBasidiobolus is a causative agent of Entomophthoromycosis and Zygomycosis. (Information from www.doctorfungus.org @ 2005)
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Taxonomic Classifications Kingdom:
Fungi
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Ecology Basidiobolus is a cosmopolitan fungus which is commonly isolated from the dung of amphibians and reptiles and as well as from plant debris or soil. Cases of human infection are mostly from Africa, tropical Asia, and South America, despite its wide distribution.
Species
Formerly the pathogenic Basidiobolus isolates have once been identified as separate species namely, Basidiobolus ranarum, Basidiobolus meristosporus, and Basidiobolus haptosporus. However, due to recent antigen analysis result shows that all pathogenic Basidiobolus isolates only belong to one species, the Basidiobolus ranarum, based on the restriction analysis of their rDNA and isoenzyme banding.
Pathogenicity and Health Effects
Basidiobolus ranarum is the etiologic agent of a type of subcutaneous chronic zygomycosis which is characterized by its granulomatous nature and formation of hard, non – ulcerating subcutaneous masses at limbs, chest, back, and buttocks and by thickening of the adjacent muscles as well. This infection is termed as entomophthoromycosis basidiobolae. Basidiobolus is considered as a true pathogen due to its ability to cause infections in immunocompromised patients. However, Basidiobolus is emerging as an opportunistic pathogen as well based on recent data on immunocompromised patients with angio - invasive infections caused by Basidiobolus. Other health effects in man due to Basidiobolus have also been reported such as gastrointestinal infections. Not only can Basidiobolus cause infections in man but in animals as well. Cases such as cutaneous lesions in amphibians, gastrointestinal lesions in dogs, and subcutaneous infection in horses have so far been reported.
Macroscopic Appearance
Ø Growth is moderately rapid with a colony diameter ranging from 1 to 3 centimeters; Ø The colony is flat and thin, the texture is waxy, and the color is yellowish to grayish on the surface while pale or white on the reverse; and Ø Satellite colonies are sometimes formed from the ejected germinated conidia.
Microscopic Appearance
Ø The hyphae are large ranging from 8 to 20 µm in diameter and more or less septated; Ø Zygospores, the sexual spores, are thick – walled and smooth or have an undulating outer cell walls and with conjugation beaks which are the remnants of a copulatory tube; Ø There are two types of Basidiobolus sporangiophores: One with inflated apices produces ejectible, unispored sporangioles which are also called ballistospores; the other one with adhesive apices produces passively liberated, unispored sporangioles; and Ø The sporulation can be observed only in freshly isolated strains while it ceases as the colony gets older or is sub – cultured; Sporulation may be stimulated by using a special medium which contains glucosamine hydrochloride and casein hydrolysate.
Laboratory Precautions
Only general laboratory precautions are required, no special safety measures needed.
Susceptibility Based on the limited data obtained, flucytosine MICs are very high, while those of fluconazole, itraconazole, ketoconazole and miconazole are considerably low for Basidiobolus strains. Basidiobolus – caused infections are difficult to treat. As a treatment, systemic potassium iodide solution and trimethoprim – sulfamethoxazole are usually referred. In some cases, oral ketoconazole and fluconazole may be of help. On the other hand, amphotericin B has almost no significant efficacy and surgery is not curative.
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