Rhodotorula mucilaginosa (A. Jörg.) F.C. Harrison 1928 and onychomycosis: three case reports for an unusual and underestimated combo

Here we describe the case reports of three patients, 35, 64, and 72 y.o. respectively, who were presented to the dermatology clinic for suspected onychomycosis with discolored and hardened nails. Both light microscopic analysis of the samples taken and culture analysis on SDA and DTM media were carried out. Direct microscopic analysis revealed the presence of yeast cells in the interstitial space of keratinocytes. Culture examinations resulted in the isolation of yeasts of the genus Rhodotorula. Subsequent metabolic and morphological analysis was conducted to ascertain the identification of the genus and species as Rhodotorula mucilaginosa. The involvement of this opportunistic pathogen in cases of onychomycosis is considered very rare and usually regarded as incidental, however, it should not be ruled out as a possible cause in favor of the more common dermatophytes or Candida spp. infections.