Molecular epidemiology of Mycobacterium avium complex isolated from patients with and without AIDS in Brazil and England

Mycobacterium avium complex (MAC) is ubiquitous throughout the world. It is an opportunistic pathogen in AIDS patients but the number of cases in HIV negative patients is also increasing. The aim of this study was to determin e whether patients were being infected with different MAC strains or whethe r one strain was dominant. DNA obtained from isolates in Brazil and England were compared using pulsed field gel electrophoresis (PFGE). Strains from 22 Brazilian patients clustered into 7 groups but 68/90 patients had a uniq ue strain. In all patients, Brazilian and English, the same strain was isol ated repeatedly over time, some over several years. This study shows that i t is most likely that Man is infected from the environment and that one str ain can survive without change for many years both in the environment and i n Man.