High phylogenetic proximity of isolates of Mycobacterium avium subsp. hominissuis over a two decades-period.

The genetic diversity of 47 human isolates of Mycobacterium avium subsp. hominissuis (MAH) was determined by MIRU-VNTR genotyping. Sixteen unique VNTR patterns and eight clusters including a total 39 isolates were detected; six clusters included strains isolated during at least a 15-year period. Minimum spanning tree analysis showed that 14 VNTR patterns, occurring either as clustered or unique isolates, differed from the nearest one for one allelic variation and that the remaining two patterns differed for two allelic variations. The high phylogenetic proximity of the isolates, even over a long time period, indicates that the MAH genotype is highly homogeneous and conserved.