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.
Formerly the pathogenic
Basidiobolus isolates have once been identified as separate species
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
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.
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.
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.
Only general laboratory
precautions are required, no special safety measures needed.
Based on the limited data obtained, flucytosine MICs are very high, while those of fluconazole, itraconazole, ketoconazole
and miconazole are considerably low for 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.