Genotyping and drug susceptibility patterns of Mycobacterium avium subsp. hominissuis isolates from different hosts

Mycobacterium avium subsp. hominissuis (MAH) causes mainly pulmonary infection in immunocompetent hosts, disseminated infection in immunocompromised hosts, such as individuals infected with human immunodeficiency virus (HIV), and infection in pigs. To examine the features of MAH isolates from different origins, we performed molecular epidemiological analysis and drug susceptibility testing using eight drugs, including clarithromycin, rifampicin, ethambutol, streptomycin, and amikacin. Phylogenetic analysis based on the allelic profile of whole-genome multi-locus sequence typing of 156 strains, including those from Japan, Europe, the United States, and Taiwan, revealed that 93.6% of isolates from patients with pulmonary MAH disease and 61.5% of isolates from HIV-positive patients formed clusters unique to Japanese strains, whereas the remaining isolates from HIV-positive patients and all isolates from pigs were included in other clusters formed by strains from Europe, the United States, and Taiwan. Thus, isolates from patients with pulmonary MAH disease and pigs were genetically distinct, and isolates from HIV-positive patients were classified into two distinct genetic types. Furthermore, isolates from patients with pulmonary MAH disease were significantly more resistant to seven drugs, excluding rifampicin, compared with other isolates. These results indicate that MAH isolates from three different origins in Japan have different genetic and drug susceptibility characteristics.