Giant grains of nocardia actinomycetoma

Abstract

A 27-year-old woman presented to a tertiary centre for mycology in Mexico City, Mexico, with an 11-year history of progressive swelling and deformity of her right foot, and was no longer able to weight-bear. Clinically, there were draining sinuses and giant, white grains with a seropurulent discharge (fi gure, A). A radiograph of her foot showed marked soft tissue enlargement and bony lytic lesions (fi gure, B). Direct microscopy of the grains showed characteristic features of nocardia (fi gure, C). Histopathology of a skin biopsy showed grains together with a granulomatous infl ammatory reaction (fi gure, D). Culture confi rmed the presence of Nocardia brasiliensis. The patient had previously been treated unsuccessfully with oral penicillin, which is not a recommended treatment for actinomycetomas. Given the incapacitating nature of her disease and bony involvement, she was treated parenterally with amikacin (500 mg twice daily) and imipenem (500 mg three-times daily) for 3 weeks after which she was given oral co-trimoxazole (800 mg sulfamethoxazole and 160 mg trimethoprim daily) and dapsone (100 mg daily). She was cured both clinically and microbiologically (negative microscopy and culture), with complete resolution of sinuses after 6 months of oral treatment. Oral treatment was continued for a further year after cure to prevent relapse, and she remains disease-free 2 years and 10 months later. The clinical features of this case, especially the presence of discharging white grains, are highly suggestive of a mycetoma. Additionally, mycetomas characteristically aff ect the extremities as a result of traumatic inoculation of the causative organism. Despite mycetomas being endemic in Mexico, cases are frequently unrecognised and incorrectly managed medically or inappropriately excised surgically. The presence of giant grains is unusual and cannot be accounted for by disease severity or chronicity. Giant grains are probably a feature of a distinct subspecies of nocardia. Molecular tests can be used to identify subspecies, although they were not done in this case.