Excisional biopsy of the brain lesion was performed.Frozen section revealed multiple granulomas suspicious for tuberculosis (Fig. 3). Treatment with isoniazid 300 mg daily, rifampin 600 mg daily, pyrazinamide 1000 mg daily, and ethambutol 800 mg daily was initiated. Dexamethasone was continued with gradual tapering. Acid-fast staining of the brain tissue was negative, but gene probe testing was positive for Mycobacterium tuberculosis complex by using the AccuProbe Culture Identification Test (Gen-Probe, San Diego, Calif). The culture grew Mycobacterium africanum on day 36 that was susceptible to isoniazid, rifampin, ethambutol, and pyrazinamide. Confirmation of M. africanum was done at the microbiology laboratory of the New York State Department of Health by a polymerase chain reaction-based genomic deletion assay (not commercially available). Although the patient had no respiratory complaints, culture of induced sputum also showed M. africanum.
The patient's symptoms improved on antituberculous therapy. Human immunodeficiency virus enzyme-linked immunosorbent assay was negative. The patient subsequently recalled having been in contact with her uncle, who was having pulmonary tuberculosis in Sierra Leone.
Treatment of brain tuberculomas by medical therapy alone can be successful, and surgical intervention is recommended if the diagnosis is uncertain or in the event of failure to respond to antituberculous therapy.11-13 On antituberculous treatment, existing tuberculomas may paradoxically enlarge, and new granulomas may appear, despite adequate therapy.14,15 This phenomenon does not necessarily imply failure of therapy; immune-mediated mechanisms have been suggested as a cause. 16 Medical therapy should be continued, and steroids dose may improve symptoms and outcome.16 Surgical intervention, however, may be needed for lesions that continue to enlarge or persist or in the event of complications such as hydrocephalus.17
In view of advanced diagnostic modalities and increasing trends of immigration, clinicians and microbiologists should be alert to the potential of M. africanum to cause disease in the United States.
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