DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 139
Nannizzia nana (Fuentes) Gräser & de Hoog
Synonymy: Microsporum nanum Fuentes
Nannizzia nana is a geophilic and zoophilic fungus frequently causing chronic noninflammatory
lesions in pigs and a rare cause of tinea in humans. Also present in soil of
pig-yards. Infections in man are usually contracted directly from pigs or fomites. Invaded
hairs may show a sparse ectothrix or endothrix infection but do not fluoresce under
Wood’s ultra-violet light. The geographical distribution is worldwide. RG-2 organism.
Morphological Description: Colonies are flat, cream to buff in colour with a suedelike
to powdery surface texture. Young colonies have a brownish-orange pigment which
deepens into a dark reddish-brown with age. Cultures produce numerous small ovoid
to pyriform macroconidia with one to three (mostly two) cells, with relatively thin, finely
echinulate (rough) walls, and broad truncate bases. Many macroconidia are borne on
conidiophores (stalks) which do not stain readily. Occasional clavate microconidia are
present, which distinguishes N. nana from some species of Chrysosporium.
Key Features: Distinctive macroconidia and culture characteristics.
Molecular Identification: ITS sequencing is recommended.
References: Rebell and Taplin (1970), Rippon (1988), Gräser et al. (2008), Cafarchia
et al. (2013), de Hoog et al. (2015, 2016).
a
b
20 µm
Nannizzia nana (a) culture and (b) macroconidia.