Multidrug-resistant tuberculosis clusters and transmission in Taiwan [TB0154]

In a population-based study, 297 cases of MDR-TB accounted for 1.0% of the 30,193 TB cases reported from 2019 to 2022. Among these, 219 (73.7%) were male, and 78 (26.3%) were female, with a median age of 63 years (ranging from 50 to 76 years). Of the cases, 242 (81.5%) were new, 52 (17.5%) were previously treated, and 3 (1.0%) had an unknown treatment history.

A maximum-likelihood phylogenetic tree was constructed based on 3,453 SNPs in the non-repetitive regions of the studied isolates, which included 45 (15.2%) pre-XDR and 6 (2.0%) XDR-TB cases. Lineage 2 isolates were predominant, comprising 43 (14.5%) sublineage 2.1 (proto-Beijing) and 145 (48.8%) sublineage 2.2 (modern Beijing) isolates. Using a 12-SNP cut-off, 25.3% (75/297) of MDR-TB cases were grouped into 20 clusters, with cluster sizes ranging from 2 to 13 cases.

Univariate analysis revealed a correlation between MDR-TB clusters and male sex. Individuals carrying the sublineage 2.1 proto-Beijing genotype had a higher risk of transmitting the infection. We identified putative compensatory mutations in the rpoA, rpoC, or non-RRDR regions of the rpoB genes in 161 (54.2%) MDR isolates. The most predominant mutation was rpoC V483G (17/161, 10.6%), followed by rpoC A172V (14/161, 8.7%) and rpoC E750D (14/161, 8.7%).

The putative compensatory mutation rpoC E750D was not previously reported and was found exclusively among sublineage 2.1 isolates. Additionally, 43.4% (129/297) of M. tuberculosis isolates harbored concurrent compensatory mutations with the rpoB S450L mutation. Notably, these mutations were significantly associated with clustering. Specifically, rpoC E750D in sublineage 2.1 and rpoC D485Y/rpoC E1140D in sublineage 2.2 were associated with MDR-TB transmission. 

Liu, K.H., Xiao, Y.X. and Jou, R., 2024. Multidrug-resistant tuberculosis clusters and transmission in Taiwan: a population-based cohort study. Frontiers in Microbiology, 15, p.1439532. https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1439532/full

(Yoseph Samodra)