POLYCLONAL MYCOBACTERIUM-AVIUM COMPLEX INFECTIONS IN PATIENTS WITH NODULAR BRONCHIECTASIS

Mycobacterium avium complex (MAC) isolates among patients with chronic lung disease were studied for their heterogeneity using genetic ident ification methods, pulsed field gel electrophoresis (PFGE) and seroagg lutination. 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 robe cavitary disease who were younger (mean age 52 yr), predominantly male (78%), and heavy sm okers (mean 56 pack-yr). A mean of 2.9 PFGE types (genotypes) per pati ent (range, 1 to 9) were identified in the nodular bronchiectasis grou p, 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 gen otypes were identified in the patients with cavitary disease, with onl y 1 of 9 (11%) having two or more genotypes. Mycobacterium intracellul are was the most frequently recovered genotype in both groups and most isolates were rough or nontypable by seroagglutination. Some genotype s from the same patient considered different by current PFGE criteria had the same serotype and shared 11 to 20 common PFGE bands, suggestin g they were related. These data demonstrate that patients with nodular bronchiectasis have multiple and/or repeated infections due to MAC wh ereas patients with upper lobe cavitary disease are usually infected w ith only a single strain.