Use of restriction fragment length polymorphism as a genetic marker for typing Mycobacterium avium strains

Restriction fragment length polymorphism (RFLP) was used to study 75 clinical isolates identified as Mycobacterium avium. Two repetitive insertion sequences, IS1311 and IS900, were used as DNA probes. Although less than 25 % of isolates showed RFLP patterns with IS900, all strains gave banding patterns with IS1311. M. avium strains isolated from patients with AIDS exhibited marked polymorphism with both probes. Mycobacteria of the Mycobacterium avium complex (MAC) behave as opportunistic pathogens and can be isolated from environmental, animal, and human sources. M. avium partic-ularly causes disseminated bacterial infections in patients with AIDS (12, 13). Human sources of infection and routes of transmission ofM. avium are not completely clear. Nevertheless, study of these factors is important to clarify the epidemiology of infection of AIDS patients with this potential pathogen. Molecular biology techniques which allow differentiation of strains within the M. avium group are important approaches for epidemiologica