DESCRIPTIONS OF MEDICAL FUNGI
fungus3-book
fungus3-book
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
124<br />
Descriptions of Medical Fungi<br />
Microsporum Gruby<br />
A recent multilocus phylogenetic study the has reviewed the taxonomy of the<br />
dermatophytes. Arthroderma now contains 21 species, Epidermophyton one species,<br />
Lophophyton one species, Microsporum three species, Nannizzia nine species<br />
and Trichophyton 16 species. In addition, two new genera have been introduced:<br />
Guarromyces containing one species and Paraphyton three species (de Hoog et al.<br />
2016).<br />
The genus Microsporum is now restricted to just three species: M. audouinii, M.<br />
canis and M. ferrugineum. The remaining geophilic and zoophilic species, previously<br />
considered Microsporum species, have been transferred to the genera Lophophyton<br />
and Nannizzia.<br />
Microsporum species may form both macro- and microconidia, although they are not<br />
always present. Cultures are mostly granular to cottony, yellowish to brownish, with a<br />
cream-coloured or brown colony reverse. Macroconidia are hyaline, multiseptate, with<br />
thick rough cell walls, and are clavate, fusiform or spindle-shaped. Microconidia are<br />
single-celled, hyaline, smooth-walled, and are predominantly clavate in shape.<br />
Note: Strains of M. canis often do not produce macroconidia and/or microconidia on<br />
primary isolation media and subcultures onto polished rice grains or lactritmel agar<br />
are recommended to stimulate sporulation. These non-sporulating strains of M. canis<br />
are often erroneously identified as M. audouinii and it is surprising just how many<br />
laboratories have difficulty in differentiating M. canis and M. audouinii.<br />
Molecular Identification: ITS sequencing is recommended (Gräser et al. 1998, 2000,<br />
Brillowska-Dabrowska et al. 2013).<br />
References: Rebell and Taplin (1970), Rippon (1988), McGinnis (1980), Domsch et<br />
al. (1980), Ajello (1977), Weitzman et al. (1986), Mackenzie et al. (1986), Kane et<br />
al. (1997), de Hoog et al. (2000, 2015), Gräser et al. (1999a, 2008). Cafarchia et al.<br />
(2013).<br />
a<br />
b<br />
(a) Microsporum audouinii showing poor growth on rice grains, usually being<br />
visible only as a brown discolouration. (b) Microsporum canis on rice grains<br />
showing good growth, yellow pigmentation and sporulation.