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Bipolaris spp.
(described by van Tieghem in 1876) Berkhout, 1923 nom. cons.

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Taxonomic Classification

Kingdom: Fungi
Phylum: Ascomycota
Class: Euascomycetes
Order: Pleosporales
Family: Pleosporaceae
Genus: Bipolaris

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.


The genus Bipolaris contains several species. Among these, three well-known pathogenic species are Bipolaris spicifera, Bipolaris australiensis, and Bipolaris hawaiiensis.


See the summary of synonyms and teleomorph-anamorph relations for the Bipolaris spp.

Pathogenicity and Clinical Significance

Bipolaris 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 [1461, 1475, 1487, 1495, 1586, 1680, 1739, 1799, 1847, 1873, 1936, 1956, 2042, 2177, 2182, 2297, 2345, 2359].

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 [2387]. It may cause nasal mycotic granuloma in the cattle [1753]. 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 [462, 1295, 2144].

Microscopic Features

The 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 [462, 1295, 1495, 1548, 2144].

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.

Histopathologic Features

Phaeoid hyphae (diameter: 2-6 µm) with frequent septations are observed. The hyphae may be branched or constricted at points of septations [462].

Compare to

Curvularia, Dissitimurus, Drechslera, Embellisia, Exserohilum, Helminthosporium

Key Features for Differentiation

Fusoid to cylindrical conidia that are evenly pigmented Bipolaris (+)
Curvularia* (-)
Distoseptate conidia Bipolaris (+)
Curvularia** (-)
Profuse conidiation Bipolaris (+)
Drechslera (-)
Slight protrusion at conidial hilum Bipolaris (+)
Drechslera (-)
Germ tube perpendicular to conidial axis Bipolaris (-)
Drechslera (+)
Germ tube originating from any cell of conidium (not only from terminal cell) Bipolaris (-)
Drechslera (+)
>5 septa in conidia Bipolaris (-)
Exserohilum (+)
Strong protrusion at conidial hilum Bipolaris (-)
Exserohilum (+)
Geniculate sympodial conidiophores Bipolaris (+)
Helminthosporium*** (-)
Conidia which are larger at the base (obclavate in shape) Bipolaris (-)
Helminthosporium (+)

*Central conidial cell is darker and larger
**Conidia are septate from one side wall to other (not distoseptate)
***Have erect conidiophores

Laboratory Precautions

No special precautions other than general laboratory precautions are required.


In 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 [1864].

Amphotericin B and ketoconazole are used in treatment of Bipolaris infections. Surgical debridement may be indicated in some cases, such as sinusitis [1936].





Bipolaris spicifera
Bipolaris spicifera
Bipolaris sorokiana
Bipolaris sorokiana


462. Collier, L., A. Balows, and M. Sussman. 1998. Topley & Wilson's Microbiology and Microbial Infections, 9th ed, vol. 4. Arnold, London, Sydney, Auckland, New York.

1295. Larone, D. H. 1995. Medically Important Fungi - A Guide to Identification, 3rd ed. ASM Press, Washington, D.C.

1461. Maskin, S. L., R. J. Fetchick, C. R. Leone, Jr., P. K. Sharkey, and M. G. Rinaldi. 1989. Bipolaris hawaiiensis-caused phaeohyphomycotic orbitopathy. A devastating fungal sinusitis in an apparently immunocompetent host. Ophthalmology. 96:175-9.

1475. McAleer, R., D. B. Kroenert, J. L. Elder, and J. H. Froudist. 1981. Allergic bronchopulmonary disease caused by Curvularia lunata and Drechslera hawaiiensis. Thorax. 36:338-344.

1487. McGinnis, M. R., G. Campbell, W. K. Gourley, and H. L. Lucia. 1992. Phaeohyphomycosis caused by Bipolaris spicifera: an informative case. Eur. J. Epidemiol. 8:383-6.

1495. McGinnis, M. R., M. G. Rinaldi, and R. E. Winn. 1986. Emerging agents of phaeohyphomycosis: pathogenic species of Bipolaris and Exserohilum. J. Clin. Microbiol. 24:250-9.

1548. Mitchell, T. G. 2000. Overview of basic medical mycology. Otolaryngol Clin N Amer. 33:237-249,VII.

1586. Morton, S. J., K. Midthun, and W. G. Merz. 1986. Granulomatous encephalitis caused by Bipolaris hawaiiensis. Archives of Pathology & Laboratory Medicine. 110:1183-5.

1680. Ogden, P. E., D. L. Hurley, and P. T. Cain. 1992. Fatal fungal endarteritis caused by Bipolaris spicifera following replacement of the aortic valve. Clin. Infect. Dis. 14:596-8.

1739. Pavan, P. R., and C. E. Margo. 1993. Endogenous endophthalmitis caused by Bipolaris hawaiiensis in a patient with acquired immunodeficiency syndrome [letter]. Amer. J. Ophthalmol. 116:644-5.

1753. Penrith, M. L., J. J. Van der Lugt, M. M. Henton, J. A. Botha, and J. C. Stroebel. 1994. A review of mycotic nasal granuloma in cattle, with a report on three cases. Journal of the South African Veterinary Association. 65:179-83.

1799. Pingree, T. F., G. R. Holt, R. A. Otto, and M. G. Rinaldi. 1992. Bipolaris-caused fungal sinusitis. Otolaryngology - Head & Neck Surgery. 106:302-5.

1847. Pritchard, R. C., and D. B. Muir. 1987. Black fungi: a survey of dematiaceous hyphomycetes from clinical specimens identified over a five year period in a reference laboratory. Pathology. 19:281-4.

1864. Radford, S. A., E. M. Johnson, and D. W. Warnock. 1997. In vitro studies of activity of voriconazole (UK-104,496), a new triazole antifungal agent, against emerging and less-common mold pathogens. Antimicrob. Agents Chemother. 41:841-843.

1873. Rao, A., R. Forgan-Smith, S. Miller, and H. Haswell. 1989. Phaeohyphomycosis of the nasal sinuses caused by Bipolaris species. Pathology. 21:280-1.

1936. Robson, J. M., P. G. Hogan, R. A. Benn, and P. A. Gatenby. 1989. Allergic fungal sinusitis presenting as a paranasal sinus tumour. Australian & New Zealand Journal of Medicine. 19:351-3.

1956. Rolston, K. V. I., R. L. Hopfer, and D. L. Larson. 1985. Infections caused by Drechslera species: Case report and review of the literature. Rev. Infect. Dis. 7:525-529.

2042. Schell, W. A. 2000. Unusual fungal pathogens in fungal rhinosinusitis. Otolaryngol Clin N Amer. 33:367-373,X.

2144. St-Germain, G., and R. Summerbell. 1996. Identifying Filamentous Fungi - A Clinical Laboratory Handbook, 1st ed. Star Publishing Company, Belmont, California.

2177. Straka, B. F., P. H. Cooper, and B. A. Body. 1989. Cutaneous Bipolaris spicifera infection. Arch. Dermatol. 125:1383-6.

2182. Stringer, S. P., and M. W. Ryan. 2000. Chronic invasive fungal rhinosinusitis. Otolaryngol Clin N Amer. 33:375-387,X.

2297. Vartivarian, S. E., E. J. Anaissie, and G. P. Bodey. 1993. Emerging fungal pathogens in immunocompromised patients: classification, diagnosis, and management. Clin. Infect. Dis. 17:S487-91.

2345. Wadhwani, K., and A. K. Srivastava. 1984. Fungi from otitis media of agricultural field workers. Mycopathologia. 88:155-9.

2359. Walsh, T. J., C. Gonzalez, E. Roilides, B. u. Mueller, N. Ali, L. L. Lewis, T. O. Whitcomb, D. J. Marshall, and P. A. Pizzo. 1995. Fungemia in children infected with the human immunodeficiency virus: New epidemiologic patterns, emerging pathogens, and improved outcome with antifungal therapy. Clin. Infect. Dis. 20:900-906.

2387. Waurzyniak, B. J., J. P. Hoover, K. D. Clinkenbeard, and R. D. Welsh. 1992. Dual systemic mycosis caused by Bipolaris spicifera and Torulopsis glabrata in a dog. Veterinary Pathology. 29:566-9.

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