Disseminated Mycobacterium gordonae infection in an immunocompetent host

Mycobacterium gordonae is a slow-growing mycobacterium that is the least pathogenic of the mycobacteria. Infection with M. gordonae is most commonly reported in immunocompromised patients. We present a rare case of M. gordonae infection in an immunocompetent individual. A 37-year-old woman was found to have a pulmonary nodule in the left upper lobe. The patient denied any respiratory symptoms, including cough, sputum production, fever, chest pain, or shortness of breath. The patient was a lifetime nonsmoker. Physical examination was normal. Computed tomography (CT) scan of the chest revealed several discrete pleural-based inflammatory infiltrates bilaterally. The patient was treated with oral amoxicillin-clavulinic acid initially and a repeat CT scan chest was scheduled after 2 weeks. Laboratory data were nonsignificant. Repeat CT scan did not show any resolution. Patient positron emission tomography scan revealed marked hypermetabolic uptake involving bilateral parenchymal nodules, mediastinal lymph nodes, and the spleen. A thoracotomy with biopsy of the left upper lobe nodule revealed necrotizing granulomatous pneumonitis with rare acid-fast bacilli. Cultures were positive for M. gordonae. The patient was started on a multidrug regimen of azithromycin, rifampin, and ciprofloxacin, based on drug sensitivities, for 12 months. Repeat CT scan and positron emission tomography scan after treatment showed complete resolution. The patient has remained disease-free 5 years after treatment. Instead of always dismissing M. gordonae as a contaminant, we should include it in our differential diagnosis of pulmonary infection in both immunocompetent and immunocompromised hosts. Further studies are needed to understand the pathogenesis of M. gordonae infection in humans.