Isolation and identification of Nocardia asteroids complex isolated from thigh abscess in a patient with Behçet's syndrome: the first report from Iran

Nocardia species are Gram-positive، partially acid fast، non-motile، catalase positive، aerobic and saprophytic actinomycetes found all around the world. They invade the human body from the environment via trauma and respiratory tract and cause cutaneous، pulmonary and systemic diseases. They are able to grow in various media. The organisms opportunistically infect both immunocompromised and immunocompetent individuals. Behcet''s disease is an autoimmune disease and immunocompromised patient which may suitable host for Nocardia bacterium. The present study is the first case report of isolation of Nocardia from the thigh abscess in a patient with behcet’s disease from Iran. A 39-year-old man with Behcet’s disease in August 2011 was admitted to Shariati hospital Tehran، with swelling and pain in the left flank and left thigh. Microscopic identification from direct microbiological slide of thigh abscess discharge demonstrated number of lymphocytes، neutrophils and macrophages foamy and white blood cells together with filamentous bacteria. Further microbiological characterization using phenotypic and antibiogram tests with disk diffusion method، demonstrated that the isolated bacterium is Nocardia asteroides complex. The bacteria were sensitive to ampicillin، vancomycin، ceftriaxone، amikacin and cotrimoxazole but it was resistant to clindamycin، erythromycin، penicillin G، cephalothin and gentamicin. The patient was treated with cotrimoxazole. Because of the high incidence and high mortality of Nocardia infection in immunocompromised cases، rapid detection and timely treatment for these patients is necessary.