[Study of the sugar composition of Conidiobolus strains saprophytic or pathogenic to man and animal]

Human Pathogenic Entomophthorales

The pathogenic entomophthoralean fungi cause infection in insects and mammalian hosts. Basidiobolus and Conidiobolus species can be found in soil and insect, reptile, and amphibian droppings in tropical and subtropical areas. The life cycles of these fungi occur in these environments where infecting sticky conidia are developed. The infection is acquired by insect bite or contact with contaminated environments through open skin. Conidiobolus coronatus typically causes chronic rhinofacial disease in immunocompetent hosts, whereas some Conidiobolus species can be found in immunocompromised patients. Basidiobolus ranarum infection is restricted to subcutaneous tissues but may be involved in intestinal and disseminated infections. Its early diagnosis remains challenging due to clinical similarities to other intestinal diseases. Infected tissues characteristically display eosinophilic granulomas with the Splendore-Höeppli phenomenon. However, in immunocompromised patients, the above-mentioned inflammatory reaction is absent. Laboratory diagnosis includes wet mount, culture serological assays, and molecular methodologies. The management of entomophthoralean fungi relies on traditional antifungal therapies, such as potassium iodide (KI), amphotericin B, itraconazole, and ketoconazole, and surgery. These species are intrinsically resistant to some antifungals, prompting physicians to experiment with combinations of therapies. Research is needed to investigate the immunology of entomophthoralean fungi in infected hosts. The absence of an animal model and lack of funding severely limit research on these fungi.

Entomophthoromycosis due to Conidiobolus

Entomophthoromycosis due to Conidiobolus coronatus is a granulomatous infection characterized by lesions that originate in the inferior turbinate, spread through ostia and foramina to involve the facial and subcutaneous tissues and paranasal sinuses. The majority of the cases have been described from areas of tropical rainforest in West Africa, agricultural and outdoor workers (aged 20-60 years) being the ones most frequently affected. The fungus is common in soil and decaying vegetation. Infection probably occurs by implantation of the spores of the fungus in nasal mucosa. C. incongruus is a rare agent of the disease, so far known only from two cases with lesions involving the pericardium, mediastinum, lungs, liver, oesophagus and jejunum. C. coronatus is known to cause a clinically similar disease in horses, mules, a dolphin and a chimpanzee. A characteristic histological feature is the presence of thin-walled, broad, often septate hyphae or hyphal fragments with a thick eosinophilic sheath, frequently phagocytosed within giant cells. The fungus is known to produce in vitro several enzymes, e.g., elastase, esterase, collagenase and lipase, which have a possible role in pathogenicity. A concentrated brain heart infusion culture filtrate antigen is useful for immunodiagnosis. Several drugs e.g., potassium iodide, cotrimoxazole, amphotericin B, ketoconazole and itraconazole have been tried with varying success. Investigations on the immunology of disease and the role of proteases and lipases in the pathogenesis of infection is an important area of further research.

Equine zygomycosis caused by Conidiobolus lamprauges

A 15-year-old Arabian mare from southern Louisiana with a 2-month history of periodic epistaxis and severe weight loss had a large, fibrosing, granulomatous mass containing numerous nodules ("kunkers") projecting dorsally into the nasopharynx, and was euthanized at the owner's request. In addition to these kunkers, the mass contained a single trematode tentatively identified as Fasciola hepatica. Several kunkers were removed, washed thoroughly in sterile water and embedded in nutrient agars; the fungus that grew out of them was identified as Conidiobolus lamprauges Drechsler (Entomophthorales: Ancylistaceae). This is the first report of C. lamprauges from any vertebrate mycosis, and only the third Conidiobolus species reported from vertebrates. Unlike many other entomophthoraleans, the fungus isolated from this mycosis grew well at 37 degrees C. The possible means by which Conidiobolus species may infect vertebrates is discussed. These mycoses probably result most often from chronic exposure during sleep to conidia discharged from fungal growth on decaying plant material in the bedding.