Genotyping of Mycobacterium intracellulare isolates and clinical characteristics of lung disease

BACKGROUND: Variable number of tandem repeats (VNTR) loci were recently identified in Japanese isolates of Mycobacterium intracellulare. We hypothesised that some mycobacterial genotypes are more virulent than others, resulting in particular genotypes being associated with disease phenotype and progression. OBJECTIVE: To evaluate the VNTR loci of M. intracellulare in clinical isolates from Korean patients, and investigate the association between mycobacterial genotype and disease phenotype and progression. DESIGN: In total, 70 M. intracellulare clinical isolates were genotyped using 16 M. intracellulare VNTR loci. RESULTS: VNTR typing showed strong discriminatory power and genetic diversity for molecular epidemiological studies of M. intracellulare. In a phylogenetic tree, the M. intracellulare clinical isolates were divided into two clusters (A and B). Cluster A was observed more frequently (77%) than Cluster B; however, there was no association between the clinical characteristics, disease progression, drug susceptibility and clusters based on VNTR genotyping. CONCLUSIONS: VNTR typing could be used for epidemiological studies of M. intracellulare lung disease; however, no association was found between the specific VNTR genotypes of M. intracellulare and the clinical characteristics of Korean patients.