[Sporotrichoid nocardiosis by Nocardia brasiliensis]

Nocardia brasiliensis is a gram-positive, branched, aerobic, acid-resistant, rod-shaped bacillus that inhabits in soil, rotten organic matter and waters. Cutaneous nocardiosis in immunocompetent individuals can manifest in three different forms: actinomycetoma, superficial skin infection or lymphocutaneous infection. A case of an 85-year-old woman with an ulcerated lesion on the back of her left hand with erythematous papules in the lymphatic tract infected by N. brasiliensis is described. The microorganism was presumptively identified by conventional and inexpensive methods for a medium complexity laboratory at the species level. The morphological characteristics of colonies, the mold smell, a positive Kinyoun stain and the presence of aerial mycelium were the key tests to identify the genus. Species level identification was confirmed by mass spectrometry (MALDI-TOF MS). The trimethoprim-sulfamethoxazole treatment was effective as this agent was active in the susceptibility testing.