DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 31
The genus Bipolaris contains about 45 species, which are mostly subtropical and tropical
plant parasites. Recent molecular studies have recognised Bipolaris cynodontis, B.
micropus, and B. setariae as species isolated from clinical samples (da Cunha et al.
2014). However recent phylogenetic studies have transferred several well-documented
human pathogens, notably B. australiensis, B. hawaiiensis and B. spicifera to the genus
Curvularia (Manamgoda et al. 2012)
RG-1 organisms.
Bipolaris Shoemaker
Morphological Description: Colonies are moderately fast growing, effuse, grey to
blackish brown, suede-like to floccose with a black reverse. Microscopic morphology
shows sympodial development of hyaline to deep olivaceous pigmented, pseudoseptate
conidia on a geniculate or zig-zag rachis. Conidia mostly curved, canoe-shaped, fusoid
or obclavate, rarely straight, 2–14 pseudoseptate (usually more than 6), germinating
only from the ends (bipolar).
Key Features: Dematiaceous hyphomycete producing sympodial, pseudoseptate,
pale brown, long slender, gently curving conidia, which are rounded at both ends.
Comment: The genera Drechslera, Bipolaris, Curvularia and Exserohilum are all
closely related. In the past, morphological differentiation of the genera relied upon
a combination of characters including conidial shape, the presence or absence of a
protruding hilum, the contour of the basal portion of the conidium and its hilum, the
point at which the germ tube originates from the basal cell and, to a lesser degree, the
sequence and location of the first three conidial septa.
However, Manamgoda et al. (2012) have found that there is no clear morphological
boundary between genera Bipolaris and Curvularia and some species show
intermediate morphology. These authors recommend using a combined ITS and GPDH
gene analysis for definitive identification of species (Manamgoda et al. 2012).
Molecular Identification: ITS sequencing may be used to identify clinical species (da
Cunha et al. 2012a). GPDH has been determined to be the best single phylogenetic
marker of Bipolaris species (Manamgoda et al. 2012, 2014).
References: Ellis (1971, 1976), Luttrell (1978), Domsch et al. (2007), Alcorn (1983),
McGinnis et al. (1986b), Sivanesan (1987), Rippon (1988), de Hoog et al. (2000, 2015),
Manamgoda et al. (2012, 2014), da Cunha et al. (2012a).