GENETIC DIVERSITY AMONG STRAINS OF MYCOBACTERIUM-AVIUM CAUSING MONOCLONAL AND POLYCLONAL BACTEREMIA IN PATIENTS WITH AIDS

To define the genetic diversity among Mycobacterium avium isolates fro m human immunodeficiency virus-infected patients, specimens were cultu red prospectively, and isolates obtained from 14 patients (4 with posi tive blood, stool, and sputum; 6 with positive blood and stool; 3 with positive blood only; and 1 with positive stool only) were studied. Bo th serotyping and ribotyping had limited ability to discriminate among isolates from different patients, whereas the distinctive restriction fragment profiles resolved by pulsed-field gel electrophoresis indica ted that each patient was infected by a unique strain. Of the 13 bacte remic patients, 2 were bacteremic concurrently with 2 distinct strains . The fact that M. avium isolates from AIDS patients exhibit considera ble genetic diversity supports the hypothesis that the infection is ac quired from various environmental sources. Further, individual patient s are not infrequently bacteremic with > 1 strain simultaneously, whic h may need to be considered in protocols for the diagnosis and managem ent of M. avium disease.