DESCRIPTIONS OF MEDICAL FUNGI

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Descriptions of Medical Fungi
Rhizopus Ehrenberg ex Corda.
A molecular phylogenetic study of the genus Rhizopus by Abe et al. (2010) recognised
eight species; R. caespitosus, R. delemar, R. homothallicus, R. microsporus, R. arrhizus
(R. oryzae), R. reflexus, R. schipperae and R. stolonifer. Based on these results and
confirmed by Dolatabadi et al. (2014) the previous varieties of Rhizopus microsporus
(R. microsporus var. oligosporus and R. microsporus var. rhizopodiformis) have been
reduced to synonyms. In addition, R. azygosporus has been reduced to a synonym of
R. microsporus. Finally, the controversy surrounding which species name to use for
R. oryzae - R. arrhizus has been resolved in favour of the latter (Ellis 1985, de Hoog
et al. 2015). Thus the important medical pathogens have now been reduced to just
R. arrhizus and R. microsporus. These two species are the most common causative
agents of mucormycosis, accounting for some 60% of the reported cases.
Morphological Description: The genus Rhizopus is characterised by the presence of
stolons and pigmented rhizoids, the formation of sporangiophores, singly or in groups
from nodes directly above the rhizoids, and apophysate, columellate, multispored,
generally globose sporangia. After spore release the apophyses and columella often
collapse to form an umbrella-like structure. Sporangiospores are globose to ovoid,
one-celled, hyaline to brown and striate in many species. Colonies are fast growing
and cover an agar surface with a dense cottony growth that is at first white becoming
grey or yellowish brown with sporulation.
Molecular Identification: ITS sequencing is recommended but sequences must be
compared to those of quality controlled reference strains with updated species names.
(Alvarez et al. 2009 and Abe et al. 2010).
References: Domsch et al. (1980), McGinnis (1980), Onions et al. (1981), Scholer
et al. (1983), Schipper (1984), Schipper and Stalpers (1984, 2003), Yuan and Jong
(1984), Ellis (1985, 1986), Rippon (1988), Kwon-Chung and Bennett (1992), Samson
et al. (1995), Schipper et al. (1996), de Hoog et al. (2000, 2015), Ellis (2005b), Alvarez
et al. (2009), Abe et al. (2010), Dolatabadi et al. (2014).
Antifungal Susceptibility: R. arrhizus (Espinel-Ingroff et al. 2015a, Australian
National data); MIC µg/mL.
No. 32
AmB 280 1 7 21 30 67 112 39 3
POSA 370 1 5 14 84 161 65 29 4 4 2
ITRA 238 5 9 42 93 41 34 2 4 9
Antifungal Susceptibility: R. microsporus (Espinel-Ingroff et al. 2015a, Australian
National data); MIC µg/mL.
No. 32
AmB 189 2 23 22 95 72 22 5
POSA 180 3 12 34 60 21 4 1 2
ITRA 117 1 1 8 27 39 24 3 1 13