Characterization of genetic diversity of animal and human Mycobacterium avium strains by IS1245-IS1311 spacer typing

A PCR method previously developed for typing Mycobacterium avium was used to characterize the genetic diversity of M. avium strains isolated from swine (n = 90) and humans (n = 24). The strains were identified with IS901 PCR and IS1245 PCR: 38 strains were of IS901+ and IS1245+ genotype (M. avium subsp. avium) and 76 strains were of IS901– and IS1245+ genotype (M. avium subsp. hominissuis). All human isolates were IS901 negative. IS1245-IS1311 spacer typing was successfully accomplished for 59 isolates while 55 isolates gave no amplification signal. The isolates with negative typing results were additionally tested for the presence of IS1311 and all with the exception of one gave positive results. IS1245-IS1311 spacer typing failed in all IS901+ isolates as they yielded no bands. A high degree of heterogeneity among isolates was observed: 59 isolates demonstrated 43 different patterns comprising up to 6 bands.