[Unusually infected sebaceous cyst by Dermabacter hominis]

Dermabacter hominis species is constituted by Gram positive facultative anaerobic coryneform rods being part of the resident microbiota human skin, and exceptionally associated to infections in immunocompromised or severely debilitated patients. An immunocompetent young adult woman with a neck sebaceous cyst infected by D. hominis as unique etiologic agent is presented. Phenotypic identification of the causative agent was achieved through simple tests, based on the originally scheme proposed by Funke and Bernard, and feasible to be performed in a hospital Microbiology Laboratory. Phenotypic characteristics as coccoid morphology, the acrid/spermatic odor, esculin hydrolysis, the production of pyrrolidonyl-arylamidase, lysine and ornithine decarboxylase, are key tests to identify D. hominis. The matrix-asisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) confirmed the phenotypic identification.