Molecular epidemiology of Mycobacterium tuberculosis complex in Brussels, 2010–2013

Abstract

The tuberculosis (TB) incidence rate in Brussels-Capital Region is 3-fold higher than in Belgium as a whole. Eight years after the realization of initial prospective population-based molecular epidemiology investigations in this Region, a similar study over the period 2010–2013 was conducted. TB strains isolated from 945 patients were submitted to genotyping by standardized 24-locus-MIRU-VNTR typing and spoligotyping. The phylogenetic analysis showed that the LAM (16.7%) and Haarlem (15.7%) branches are the two most prevalent TB lineages circulating in Brussels. Analysis of the MDR subgroup showed an association with Beijing strains (39.9%) and patients native of Eastern Europe (40.7%). Genotyping detected 113 clusters involving 321 patients, giving a recent transmission index of 22.9%. Molecular-guided epidemiological investigations and routine surveillance activities revealed family transmission or social contact for patients distributed over 34 clusters. Most of the patients were foreign-born (75.7%). However, cluster analysis revealed only limited trans-national transmission. Comparison with the previous study shows a stable epidemiological situation except for the mean age difference between Belgian-born and foreign-born patients which has disappeared. This study confirms that molecular epidemiology has become an important determinant for TB control programs. However, sufficient financial means need to be available to perform all required epidemiological investigations.

Molecular characterisation of multidrug-resistantMycobacterium tuberculosisisolates from a high-burden tuberculosis state in Brazil

“…It was also noticed that in almost every cluster, there were isolates with the 12 nucleotide insertion in the rpo B gene. The presence of clusters with identical genotypes among the isolates is an indicator of the transmission of the same strain [ 51 ]. In this study, no correlation about the clusters and patient's information was found to determine any kind of transmission, probably due to low clustering rate of the isolates.…”

Reduced transmission ofMycobacterium africanumcompared toM. tuberculosisin urban West Africa

“…However, we observed that individuals below the age of 30 years were associated with recent TB transmission, and this is similar to observations made elsewhere. 28,30 Also from this study, we observed that each year increase in age is associated with an approximately 1% (CI: 0·13 − 2·00, p=0·007) decrease in the odds of a TB patient being part of a recent transmission event implying that, compared to younger individuals, older individuals are more likely to get active TB disease by reactivation of latent TB infection rather than through a recent transmission event. 28 This finding put age as a risk factor for recent TB transmission in Ghana.…”

Molecular typing of Mycobacterium kansasii using pulsed-field gel electrophoresis and a newly designed variable-number tandem repeat analysis

“…The first VNTRs described in mycobacteria were those identified in M. tuberculosis , collectively referred to as mycobacterial interspersed repetitive units (MIRUs) 37 . Although the panel of MIRU-VNTR loci has been modified over the years, the standardized 24-locus MIRU-VNTR typing is currently recognized as the reference typing system for M. tuberculosis complex 38 – 40 . The principle of the VNTR-based typing modalities involves PCR amplification of a predefined set of VNTR loci, by using primers annealing to their flanking sequences, and amplicon size determination to deduce the number of TR units within each locus.…”