Polyclonal Mycobacterium avium Complex Infections in Patients with Nodular Bronchiectasis

Abstract

Mycobacterium avium complex (MAC) isolates among patients with chronic lung disease were studied for their heterogeneity using genetic identification methods, pulsed field gel electrophoresis (PFGE) and seroagglutination. A mean of 7.3 cultures per patient were collected from 17 patients with nodular bronchiectasis who were elderly (mean age 66 yr), predominantly female (76%), had smoked a mean of only 5 pack-years, and had multifocal bronchiectasis. A mean of 7.7 cultures per patient were collected from nine patients with upper lobe cavitary disease who were younger (mean age 52 yr), predominantly male (78%), and heavy smokers (mean 56 pack-yr). A mean of 2.9 PFGE types (genotypes) per patient (range, 1 to 9) were identified in the nodular bronchiectasis group, with 15 of 17 patients (88%) having two or more genotypes and 9 of 17 (53%) having three or more genotypes. In contrast a mean of 1.2 genotypes were identified in the patients with cavitary disease, with only 1 of 9 (11%) having two or more genotypes. Mycobacterium intracellulare was the most frequently recovered genotype in both groups and most isolates were rough or nontypable by seroagglutination. Some genotypes from the same patient considered different by current PFGE criteria had the same serotype and shared 11 to 20 common PFGE bands, suggesting they were related. These data demonstrate that patients with nodular bronchiectasis have multiple and/or repeated infections due to MAC whereas patients with upper lobe cavitary disease are usually infected with only a single strain.

Association between 16S-23S Internal Transcribed Spacer Sequence Groups of Mycobacterium avium Complex and Pulmonary Disease

“…However, consistent with other studies (3,4,8,18,25), the majority of MAC isolates (63.9%) among study subjects with or without MAC pulmonary disease belonged to the M. intracellulare sequevar group. M. intracellulare organisms are preferentially aerosolized (compared to M. avium) (17), resulting in relatively greater potential for respiratory exposure to M. intracellulare.…”

“…Only one mycobacterial isolate per case subject was examined. MAC pulmonary disease is often polyclonal (25), and reinfection with new strains occurs frequently (24). Examining only one isolate may have resulted in misclassification of the infecting MAC sequevar in some case subjects.…”

The Effect of Combined Therapy According to the Guidelines for the Treatment of Mycobacterium avium Complex Pulmonary Disease

“…MACinfections with mixtures of susceptible and resistant strains, especially in pulmonary disease with nodules and bronchiectasis (15). Therefore, we did not mention the susceptibility teats for CAMor other antituberculous drugs.…”

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

“…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].…”