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Bipolaris Mold Species The U.S. Government's Occupational Safety and Health Administration [OSHA] lists the following as the health effects of Bipolaris mold: Allergen, Irritant, Hypersensitivity pneumonitis, Dermatitis. |
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Taxonomic Classification
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Description and Natural Habitats Bipolaris
is a dematiaceous, filamentous fungus. It is cosmopolitan in nature and is
isolated from plant debris and soil. The pathogenic species have known
teleomorphic states in the genus Cochliobolus and produce
ascospores. SpeciesThe genus Bipolaris contains several species. Among these, three well-known pathogenic species are Bipolaris spicifera, Bipolaris australiensis, and Bipolaris hawaiiensis. The genus Bipolaris contains about 45 species which are mostly subtropical and tropical plant parasites. However, several species notably B. australiensis, B. hawaiiensis and B. spicifera, are well documented human pathogens. Clinical manifestations include mycotic keratitis, subcutaneous phaeohyphomycosis, sinusitis, peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD), and cerebral and disseminated infections. Pathogenicity and Clinical SignificanceBipolaris is one of the causative agents of phaeohyphomycosis. The clinical spectrum is diverse, including allergic and chronic invasive sinusitis, keratitis, endophthalmitis, endocarditis, endarteritis, osteomyelitis, meningoencephalitis, peritonitis, otitis media (in agricultural field workers),and fungemia as well as cutaneous and pulmonary infections and allergic bronchopulmonary disease. Bipolaris can infect both immunocompetent and immunocompromised host. As well as being
isolated as saprophytes on plants, Bipolaris may be pathogenic to
certain plant species, particularly to Graminiae and also to animals, such
as the dog. It may cause nasal mycotic granuloma in the cattle. Bipolaris
may also be isolated as a laboratory contaminant. Macroscopic Features
Bipolaris colonies grow rapidly, reaching a diameter of 3 to 9 cm
following incubation at 25°C for 7 days on potato dextrose agar. The
colony becomes mature within 5 days. The texture is velvety to woolly. The
surface of the colony is initially white to grayish brown and becomes
olive green to black with a raised grayish periphery as it matures. The
reverse is also darkly pigmented and olive to black in color. Microscopic FeaturesThe hyphae are septate and brown. Conidiophores (4.5-6 µm wide) are brown, simple or branched, geniculate and sympodial, bending at the points where each conidium arises from. This property leads to the zigzag appearance of the conidiophore. The conidia, which are also called poroconidia, are 3- to 6-celled, fusoid to cylindrical in shape, light to dark brown in color and have sympodial geniculate growth pattern. The poroconidium (30-35 µm x 11-13.5 µm) is distoseptate and has a scarcely protuberant, darkly pigmented hilum. This basal scar indicates the point of attachment to the conidiophore. From the terminal cell of the conidium, germ tubes may develop and elongate in the direction of longitudinal axis of the conidium. Teleomorph production of Bipolaris is heterothallic. The perithecium is black in color, and round to ellipsoidal in shape. The ascospores are flagelliform or filiform, hyaline in nature and are found in clavate-shaped or cylindrical asci. Each ascus contains eight ascospores. Laboratory PrecautionsNo special precautions other than general laboratory
precautions are required. SusceptibilityIn vitro susceptibility testing procedures have not been standardized for dematiaceous fungi yet. Very limited data are available on susceptibility of Bipolaris. These data suggest that itraconazole MICs are variable and voriconazole MICs are considerably low. Amphotericin B and ketoconazole are used in treatment of Bipolaris infections. Surgical debridement may be indicated in some cases, such as sinusitis. |
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