Evaluation of the Selected 12-locus MIRU for Genotyping Beijing Family Mycobacterium Tuberculosis in Korea

Background: Mycobacterial Interspersed Repetitive Units (MIRUs) that are located mainly in intergenic regions dispersed throughout the Mycobacterium tuberculosis genome. The selected MIRU loci, which were composed of a 12-locus set, demonstrated a high power for discrimination of Mycobacterium tuberculosis isolates collected from Kangwon province of Korea. To evaluate its ability to discriminate the M. tuberculosis strains, 45 clinical isolates were genotyped using the methods IS6110 RFLP and MIRU. Methods: All the samples were collected during the period from January 2007 to December 2007 from TB patients, who were residents and registered to a public health center of Kangwon Province in Korea. A total of 45 DNAs were extracted from clinical isolated mycobacterial strains and genotyped using IS6110 RFLP, the MIRU method. Results: We compared the 12-MIRU with IS6110 RFLP in the 45 samples, the 12-locus version offered less discriminatory power (Hunter-Gaston discriminatory index [HGDI]: 0.959 vs 0.998; 57.78% of clustered cases vs 8.89%). Conclusion: This 12-locus MIRU can be useful when additional combinations of other loci for genotyping M. tuberculosis in Korea where the Beijing family strains are dominant.