Synchronous Comparison of Mycobacterium tuberculosis Epidemiology Strains by MIRU-VNTR and MIRU-VNTR and Spoligotyping Technique

Molecular epidemiology analyses are frequently used in determining epidemiology of tuberculosis. recently, mycobacterial interspersed repetitive unit variable number tandem repeat (miru-vntr) and spoligotyping has become an important method, as it allows high-through put, discriminatory and reproducible analysis of clinical isolate. the purpose of this study is to compare techniques of “miru-vntr” versus “miru-vntr and spoligotyping” together for study of genetic pattern of mycobacterium tuberculosis (m. tuberculosis) strains. sixty m. tuberculosis (mtb) isolates were selected (30 susceptible, 30 multi-drug resistant) for this study. thereafter, the miruvntr and spoligotyping were performed to identify their genetic patterns. the frequency of unknown genetic pattern of mtb was compared using technique of “miru-vntr” alone versus “miru-vntr and spoligotyping” together. the miru-vntr allelic diversity at each of the loci was calculated by hunter – gaston discriminatory index (hgdi). based on differentiation index of all strains 10, 16, 26, 31 and 40 loci were identified as the most distinctive (hgi ≥ 0.6) and 2, 4, 20 and 24 as the weakest distinctive locus (hgi ≤ 0.3). by using miru-vntr technique 38% (n= 23) of isolates could not be typed, whereas by applying miru-vntr and spoligotyping together only 15% (n= 9) of isolates remained unknown (p = 0.004). for sensitive strains, the difference was significant (67% vs. 90%, p = 0.028), but only marginally significant for drug resistant strains (57% vs. 80%, p = 0.052). the discrimination power of 12-locus miru-vntr and spoligotyping was equal to that of miru-vntr analysis. if appropriate loci are added to the standard miru analysis, miru-vntr genotyping could be a valuable tool for strain typing and epidemiological research of m. tuberculosis. with this approach a more clear understanding about genetic pattern of mtb can be achieved.