COMBINED NUMERICAL-ANALYSIS BASED ON THE MOLECULAR DESCRIPTION OF MYCOBACTERIUM-TUBERCULOSIS BY 4 REPETITIVE SEQUENCE-BASED DNA TYPING SYSTEMS

Mycobacterium tuberculosis clinical isolates (113 isolates from 78 pat ients) were typed using IS6110-RFLP, DR-RFLP, DR-based spoligotyping a nd direct repetitive element PCR (DRE-PCR). The similarities among iso lates were compared for each individual method. The individual matrix distance files for each method were summed and averaged, and the resul ting unique distance file was analysed by the UPGMA (unweighted pair g roup method with arithmetic averages). Combined numerical analysis wit h 3 genetic markers (IS6110-RFLP, DR-RFLP and spoligotyping) was perfo rmed for all 78 clinical isolates, whereas analysis with 4 genetic mar kers (with the addition of DRE-PCR) was performed on the 10 main clust ers described. When compared to molecular analysis based on individual markers, the molecular description based on multiple genetic markers enabled comparison of the results obtained by individual methods and t he obtaining of a more accurate view of strain identity and clusters c omparison. The resulting cumulative dendrogram was more accurate for s tudying the population structure of M. tuberculosis and may be a good tool for elucidating intraspecies genetic microevolution.