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A3591 - Nocardia Paucivorans Empyema in a Patient with Suspected Silicosis
Author Block: G. Samuel1, D. Modi2, M. Matta3, J. K. Podgore4; 1Medicine, University of North Texas Health Sciences Center, Fort Worth, TX, United States, 2Southwest Pulmonary Associates, Irving, TX, United States, 3John Peter Smith Hospital, Fort Worth, TX, United States, 4Pediatrics, University of North Texas Health Sciences Center, Fort Worth, TX, United States.
Introduction: Nocardia paucivorans was first isolated in 2000 from the bronchial secretions of a 51 year old male with chronic lung disease. Since then, case reports in the literature have described this organism in association with pulmonary and cerebral lesions, as well as disseminated disease in both immunocompetent and immunocompromised patients. We describe a case of N. paucivorans empyema in a patient with suspected underlying pulmonary silicosis. Description: A 42 year old non-smoking HIV negative Hispanic male who ingested alcohol daily, and whose work history included unprotected exposure to dust from daily stone grinding in masonry construction for over ten years, was admitted with a several week history of cough, pleuritic chest pain and fevers unresponsive to macrolide and quinolone therapy. TST and T spot testing were negative. Chest imaging was notable for extensive mediastinal and hilar calcific adenopathy, bilateral patchy parenchymal opacities in a peripheral upper lobe predominant distribution, volume loss, and a moderate left sided effusion with loculated components, some of which contained gas. Initial aspiration revealed an amber-colored exudate with a predominance of lymphocytes and mesothelial cells. Aspiration of the loculated component revealed purulent fluid. Gram positive non-filamentous rods with a branching and beaded appearance were observed in this second aspirate. He was initially treated for suspected TB, as well as amoxicillin-clavulanate to cover for aspiration pneumonia. Cultures from the second aspirate ultimately grew Nocardia paucivorans. CT of the brain demonstrated no abnormal intra-parenchymal enhancement. The isolate was fully susceptible to multiple antimicrobials, with intermediate susceptibility to amoxicillin-clavulanate. The patient improved clinically with the administration of trimethoprim-sulfamethoxazole. Discussion: Nocardia species are gram positive branching rods that are ubiquitous in soil, decaying organic matter and water, with infection occurring through inhalation or skin inoculation. Immunocompromising conditions such as HIV, organ transplantation, hematologic malignancies, and receipt of cytotoxic chemotherapy or corticosteroids are well recognized risk factors for infection, but approximately a third of cases involve apparently immunocompetent persons. Silica dust is known to impair macrophage function and elicit pro-inflammatory reactions leading to the development of pulmonary fibrosis, and is a well-known risk factor for tuberculosis. We propose that this patient was predisposed to infection with this relatively novel Nocardia species with a propensity for dissemination on the basis of underlying immune deficits secondary to longstanding silica exposure, and a compatible occupational exposure risk.