Temporal and regional dynamics of Mycobacterium tuberculosis in Oman.

Tuberculosis (TB) remains endemic in Oman, with incidence exceeding 5 per 10⁵ population since 2016 and a rising proportion of cases among expatriates (> 40% of the population). This study investigated the spatiotemporal diversity and structure of Mycobacterium tuberculosis (MTB) in Oman between 2008 and 2022. A total of 735 MTB isolates from nationals and expatriates across provinces were genotyped by spoligotyping and 17-locus MIRU-VNTR; 96 underwent whole-genome sequencing (WGS). Genetic diversity (expected heterozygosity, h) and differentiation (FST) were estimated, and phylogenetic analyses performed. Four major lineages and seven sub-lineages were identified, with similar distributions between nationals and expatriates but temporal variation in spoligotype clades. MIRU-VNTR showed high allelic diversity, with most dominant alleles (76.5%) stable over time, though 32.5% fluctuated. FST values (< 0.05) indicated minimal temporal or local differentiation, except for slightly higher values between Dhofar and other regions. WGS revealed close genetic relatedness between Omani and expatriate isolates and strains from expatriates' countries of origin, suggesting recent cross-border transmission. MTB in Oman exhibits high genetic diversity with a stable temporal structure. Shared lineages between nationals and expatriates underscore the role of migration, supporting the need for integrated genomic surveillance.