Serovars of Mycobacterium avium complex isolated from patients in

Danish isolates of Mycobacterium avium complex were serotyped by the use of seroagglutination. The most prevalent serovars among patients with AIDS (n = 89) were 4 and 6, while among non-AIDS patients the most prevalent serovars were 1, 6, and 4, with no major differences between those in patients with pulmonary disease (n = 65) and those in patients with lymph node infection (n = 58). The results suggest a Scandinavian distribution of serovars with a predominance of serovar 6 and fail to demonstrate any selective protection against different serovars by Mycobacterium bovis BCG vaccination. Before the AIDS epidemic, clinical disease due to Mycobac-terium avium complex (MAC) was rarely seen and was often confined to older patients with pulmonary disease or to apparently healthy children with cervical lymph node infec-tions. Disseminated disease was rarely encountered (16, 17). Today, MAC is the most common cause of systemic bacterial infection in patients with AIDS in the western world (5). However, the frequencies with which infections are found associated with AIDS range from 10 to 50 % in various studie