| Abstract | Standardized Mycobacterial Interspersed Repetitive Unit-Variable Number of Tandem Repeat (MIRU-VNTR) typing based on 15 and 24 loci has recently been proposed for Mycobacterium tuberculosis genotyping. So far, this optimized system has been assessed in a single, one-year population-based study performed in Germany. Here, we evaluated these optimized formats in a much larger population-based study conducted over 39 months in the Brussels-capital Region. Isolates from 807 patients were genotyped. Resolution power, cluster and lineage identification by the standardized MIRU-VNTR sets were compared with those obtained using standardized IS6110-RFLP, spoligotyping and a previous 12 MIRU-VNTR-locus set. On a subset representing 77 % of the cases over a 16-month period, a high concordance was observed between unique isolates or strain-clusters defined by standardized MIRU-VNTR and IS6110-RFLP (>5 IS6110). When extended to the entire population-based collection, the discriminatory subset of 15 loci decreased the strain-clustering rate by almost two-fold as compared to the old 12-locus set. Addition of the 9 ancillary MIRU-VNTR loci and/or spoligotyping only slightly further decreased this strain-clustering rate. Familial, social or geographic proximity links were found in 48 % of clusters identified, and well-known risk factors for tuberculosis (TB) transmission were identified. Finally, excellent correspondence was determined between our MIRU-VNTR-spoligotyping strain identifications and external reference strain lineages included in the MIRU-VNTRplus database and identified e.g. by large sequence polymorphisms (LSPs). Our results reinforce the proposal of standardized MIRU-VNTR typing as a new reference genotyping method for epidemiological and phylogenetical screening of M. tuberculosis strains. |