Nontuberculous mycobacterial lung infections in patients with eating disorders: plausible mechanistic links in a case series

Abstract

Nontuberculous mycobacteria (NTM) are widely distributed in the environment and are almost always acquired into the lungs by bioaerosol inhalation or aspiration of NTM-contaminated water, biofilms, and soil. NTM are increasingly recognized as causes of lung diseases in immunocompetent hosts, a not insignificant number of whom have a life-long or nearly life-long slender body habitus as well as thoracic cage abnormalities such as scoliosis and pectus excavatum. While several hypotheses have been offered to explain the purported increase in susceptibility to NTM lung disease in such individuals, the precise explanation remains unknown. We described three patients with eating disorders associated with severe malnutrition and either purging behaviors or other risks for aspiration who were diagnosed with NTM lung infections-the largest number of such patients to date in a single report. We discuss the clinical and experimental evidence that low body weight and chronic vomiting with attendant jeopardy for aspiration, as seen in patients with eating disorders, may represent risk factors for NTM lung disease. We also speculate the possibility of occult and undiagnosed eating disorders in some of the slender NTM lung disease patients with no known risk factors for the opportunistic infection other than their low body weight.

Keywords: Anorexia nervosa (AN); case series; leptin; nontuberculous mycobacterial lung infections; purging behaviors; severe malnutrition.

Figure 1

CT scan of Case 1 before right upper lobe (RUL) resection. Axial images showing (A) localized cavitary disease (black arrow), (B) bronchiectasis (white arrow), and nodules (arrowhead) mostly in the apical segment of the RUL. There were few tree-in-bud opacities in the lingula (not shown). (C) Coronal image showing the right apical cavities (white arrow) and bronchiectasis (white arrowheads). CT, computed tomography.

Figure 2

Images of Case 2 showing severe NTM lung disease of the left lung 7 years after a left lower lobectomy. (A) Chest X-ray demonstrating volume loss of the left lung with shift of the mediastinum to the left, opacification of the bottom two-thirds of the left hemithorax, and a possible air-fluid level. There is also increased reticular-nodular opacities of the hyperinflated right lung. (B) Axial CT scan near the carina shows evidence of necrotic left lung with severe upper lobe cavitary formation (black arrow). The right lung shows bronchiectasis (white arrow), mosaic attenuation, and patchy areas of consolidation (arrowhead). CT, computed tomography; NTM, nontuberculous mycobacterial.

Figure 3

Images of Case 3 showing unilateral nodular and cavitary densities. (A) Chest X-ray demonstrating nodular densities in the right upper lung field and a single, linear plate-like atelectasis in the left upper lung field. (B) Coronal CT scan showing complex cavitary lesions (arrow) with surrounding bronchiectasis in the right upper lobe. (C) Axial CT at the level of the aortic arch reveals an irregularly shaped density in the anterior segment of the right upper lobe suggestive of a mucous plug (arrow). There are smaller nodules in the peripheral right lower lobe. CT, computed tomography.

Figure 4

Diagram of the possible mechanisms by which individuals with anorexia nervosa may be predisposed to NTM lung disease. Please see text for discussion. NTM, nontuberculous mycobacteria; FSH, follicle stimulating hormone; LH, luteinizing hormone; IL, interleukin; TNF, tumor necrosis factor; NF-κB, nuclear factor-kappa B.