Genetic Diversity and Molecular Epidemiology of Mycobacterium tuberculosis Complex Clinical Isolates in New Brunswick, Canada—A Retrospective Chart Review

The incidence of tuberculosis disease (TBD) in New Brunswick (NB) is low but has been rising over the past decade. Analyzing these trends can help identify specific risk factors and transmission patterns to guide targeted public health strategies. This study aimed to provide a comprehensive and detailed characterization of TBD in NB by examining data from 1 January 2002, to 31 December 2024. All TB patients with Mycobacterium tuberculosis complex (MTBC) clinical isolates identified in NB healthcare facilities were eligible for inclusion in the study. We analyzed demographic, drug susceptibility, and 24-locus Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeat (MIRU-VNTR) data from 166 patients. Most MTBC isolates were pan-susceptible to first-line anti-tuberculosis drugs (90.9–98.1%), with 2.4% showing multidrug resistance. The MIRU-VNTR demonstrated a high discriminatory power of 0.9982 and a low clustering rate of 20.4%. Two samples from the same patient, collected seven years apart, showed different genetic profiles, suggesting that the second episode was a new infection. The most prevalent MTBC lineage was East African Indian (n = 23, 13%). This study provides early insights into TB trends in NB, including what may be the first recorded case of TB reinfection in NB. Our findings will help guide future TB research, policies, and public health interventions in the region.