Objective: Prompt genotyping of Mycobacterium tuberculosis (M. tuberculosis) is crucial for improving molecular epidemiological investigation of tuberculosis (TB).
Methods: We performed a retrospective study to evaluate the use of 24 loci MIRU-VNTR (mycobacterial interspersed repetitive unit-variable number of tandem-repeat) directly on 135 clinical samples from 84 TB patients.
Results: There was a direct correlation between genotyping on clinical samples by MIRU-VNTR and bacterial load (P = 0.001). VNTR loci were amplified successfully for 41.5% of the clinical samples (19-24 loci), 32.6% (13-18 loci), 23.7% (7-12 loci) and 2.2% (1-6 loci). Loci of 2401, 577, 2996 and 154 had the highest power to show the mixed strains infection in clinical samples.
Conclusions: Direct MIRU-VNTR is partially successful in complete genotyping of M. tuberculosis strains. On the other hand, detection of polyclonal infection is undoubtedly reliable based on the direct MIRU-VNTR.
Keywords: 24 loci MIRU-VNTR; Mixed infections; Mycobacterium tuberculosis; Prompt genotyping.
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