Mycetoma caused by Nocardia caviae in the first Brazilian patient

Mycetoma is a chronic subcutaneous mycosis caused by exogenous fungi or actinomycetes. This infection has a progressive course and shows a typical clinical characteristic of tumefaction, draining sinuses, and grains. Infection initiation is related to local trauma and can spread to muscle, underlying bone, and adjacent organs. Nocardia brasiliensis is the most frequent actinomycete isolated, while N. caviae is a rare agent.

We present a case of mycetoma in a 37-year-old African-American man on the right hand. The infection had been apparent for four years prior to the consultation. When the infection did not respond to antibiotic therapy, the patient was referred to the Dermatology department. Routine laboratory studies were normal. X-ray examination of the hand showed an osteolytic lesion on the hand bones. On skin biopsy culture, on Sabouraud Dextrose Agar at 28 degrees C, a colony was isolated which was further identified as N. caviae by biochemical and hydrolysis testing.

The patient was treated with oral trimethoprim/sulfamethoxazole (TMP/SMZ) 160/800 mg twice a day for 10 months. Four months after the beginning of the therapy, the subject exhibited clinical improvement and functional recovery of the hand. Five-year follow-up X-ray examination of the hand showed no osteolytic lesion on the hand bones.

We report the first mycetoma case caused by N. caviae in our country with an unusual location on the hand. The patient showed clinical improvement with oral TMP/SMZ.