Nannizzia gypsea (formerly Microsporum gypseum)

Nannizzia gypsea (formerly Microsporum gypseum)

Microsporum gypseum is a geophilic dermatophyte found worldwide in soil, where it exists as a saprophyte. The M. gypseum complex includes three anamorphic species: M. gypseum, M. fulvum, and M. incurvatum. According to recent taxonomic revisions, M. gypseum is now classified as Nannizzia gypsea.

Infections caused by the N. gypsea complex (including N. fulva and N. incurvata) are relatively rare, accounting for approximately 1% of all dermatophytic infections, ranging from <1% in Korea to 6.8% in Italy. Humans, typically gardeners or farmers, are primarily infected through direct contact with contaminated soil. Transmission can also occur indirectly through pets, with dogs and cats acting as healthy carriers.

Compared to infections caused by anthropophilic or zoophilic dermatophytes, superficial mycoses caused by geophilic species like N. gypsea are much rarer. The clinical presentation can vary, often mimicking other inflammatory dermatoses, which can cause delays in diagnosis.

Colonies on SDA have a coarse granular or powdery texture, ranging in color from deep cream to brown, with a yellowish to pale buff reverse. Macroconidia are thin-walled, ellipsoidal to fusiform, with slightly tapered ends and a rounded apex. They form individually or in clusters along the hyphae.

For localized skin infections, topical antifungal treatment is generally effective. Commonly recommended topical agents include azoles such as clotrimazole, miconazole, bifonazole, clotrimazole, sertaconazole, luliconazole, eberconazole, etc. or allylamines such as terbinafine. The treatment may be carried out for at least four weeks. The administration of systemic (oral) antifungals may be indicated in cases of extensive lesions, failure of topical therapy, or other challenging cases. In such instances, terbinafine, itraconazole, fluconazole, or griseofulvin can be used.

[Case editor: M. Drogari-Apiranthitou, Research Laboratory of Infectious Diseases, 4th Dept of Internal Medicine, National and Kapodistrian University of Athens]

References

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Dukik K, de Hoog GS, Stielow JB, Freeke J, van den Ende BG, Vicente VA, Menken SBJ, Ahmed SA. Molecular and Phenotypic Characterization of Nannizzia (Arthrodermataceae). Mycopathologia. 2020 Feb;185(1):9-35. doi: 10.1007/s11046-019-00336-9

Junior, D.C., Ramos, M.L.M., Almeida-Paes, R. et al. New Insights in Dermatophytes: Microsporum spp. and Nannizzia spp.. Curr Trop Med Rep 9, 15–27 (2022). https://doi.org/10.1007/s40475-022-00252-x

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Charpantidis S, Siopi M, Pappas G, Theodoridou K, Tsiamis C, Samonis G, Chryssou SE, Gregoriou S, Rigopoulos D, Tsakris A, Vrioni G. Changing Epidemiology of Tinea Capitis in Athens, Greece: The Impact of Immigration and Review of Literature. J Fungi (Basel). 2023 Jun 27;9(7):703. doi: 10.3390/jof9070703