Mycobacterium avium-intracellulare Pulmonary Infection in Patients Without Known Predisposing Lung Disease

Abstract

We tried to characterize the clinical features and findings on chest high resolution computed tomography (HRCT) of patients with Mycobacterium avium-intracellulare (MAI) pulmonary infection without known predisposing lung disease and with no immunodeficiency. We also aimed to clarify the small airway and alveolar inflammation using bronchoalveolar lavage (BAL) from the affected regions. MAI infection was diagnosed in 53 patients from respiratory samples, including sputum and materials obtained using a fiberoptic bronchoscope. None had a predisposing lung disease or immunodeficiency, as assessed by medical history, routine laboratory data, and previously normal chest radiographs and/or CT scans. The mean age of the 53 patients was 60 +/- 11 years, and 48 were nonsmoking females. They had few respiratory symptoms, although 42% had chronic paranasal sinusitis. Chest HRCT findings showed centrilobular small nodules and ectasia of small bronchi and/or bronchioles located mainly in segment (S) 2, 3, 4, and 5. S1, which is usually affected by pulmonary tuberculosis, was completely free of these opacities. The BAL study revealed that the predominant cells were activated T lymphocytes and neutrophils. The CD4+/CD8+ ratio increased significantly. Bacteriology was negative for other bacteria and fungi. Although our patients did not present with distinct respiratory symptoms, the regions affected by MAI showed a chronic inflammation of mainly neutrophils and activated T lymphocytes. The presence of chronic sinusitis may be merely coincidental. However, its high prevalence and the finding of bronchiectasis in chest HRCT raise the question of whether silent bronchiectasis may be a predisposition.

CT findings of pulmonary non-tuberculous mycobacterial infection in non-AIDS immunocompromised patients: a case-controlled comparison with immunocompetent patients

“…The nodular bronchiectatic form is usually seen in middle-aged or older females with no predisposing factors [14,19,25,26]. CT findings of the nodular bronchiectatic form include small centrilobular nodules with bronchiectasis, usually occurring in the same lobe [13,23,24,[27][28][29][30][31]. Similar findings were seen in the immunocompetent patients and ICPs in our study.…”

“…Pulmonary infection caused by MAC in patients with other illnesses, including chronic obstructive pulmonary disorder, previous pulmonary tuberculosis, bronchiectasis and pneumoconiosis, has been described [11,12]. Subsequently, pulmonary MAC infection in middleaged females having neither predisposing lung disease nor immunodeficiency has been reported [13][14][15].…”

Mucosal inflammation in idiopathic bronchiectasis: cellular and molecular mechanisms

“…MAC infection can cause bronchiectasis and bronchiolectasis [48,49] in subjects who show no signs of systemic immunological diseases [49][50][51]. Most of these patients are middle-aged nonsmoking females and have characteristic computed tomographic findings of peripheral nodules and bronchiectasis [52,53].…”

Nontuberculous Mycobacterium Infections in Rheumatoid Arthritis Patients

“…The HRCT findings of MAC-PD also exhibit all three forms of lung disease, as described for NTM-PD, namely cavitary disease, fibronodular bronchiectasis, and HP (Cappelluti et al, 2003;Embil et al, 1997;Glassroth, 2008;Kahana et al, 1997). Fibronoduar bronchiectasis caused by MAC is most frequently observed in women >60 years old, and compared to patients with other types of NTM infection, the lingual and right middle lobe tend to be more severely and progressively involved (Hollings et al, 2002;Kim et al, 2005;Kubo et al, 1998;Obayashi et al, 1999;Prince et al, 1989;Tanaka et al, 2001). In a recent clinical study, MAC was cultured from the sputum of 25% of the patients with fibronodular bronchiectasis, and MAC infection was documented in 50% of bronchoscopies, including BAL and transbronchial biopsies (Griffith et al, 2007).…”