Phylogenetic lineages of tuberculosis isolates in New Zealand and their association with patient demographics

SETTING: In New Zealand, the lineage genotypes of Mycobacterium tuberculosis clinical isolates and their role in the epidemiology of tuberculosis (TB) are currently unknown.

OBJECTIVE: 1) To measure the relative frequency of each phylogenetic lineage of the M. tuberculosis complex in New Zealand, and 2) to examine its relationship with patient demographics and multidrug-resistant TB (MDR-TB).

METHODS: All non-duplicate M. tuberculosis complex isolates recovered in 2010 and 2011 underwent large sequence polymorphism and/or single nucleotide polymorphism analyses. Mycobacterial interspersed repetitive units (MIRU) profiling was also performed for cluster identification.

RESULTS: New Zealand isolates were dominated by lineage 4 (Euro-American: 37.8%, 95%CI 33.6-42.2), followed by lineage 1 (Indo-Oceanic: 22.6%, 95%CI 19.1-26.5), lineage 2 (East Asian: 19.5%, 95%CI 16.2-23.3) and lineage 3 (East-African Indian, which included Central Asian: 17.7%, 95%CI 14.5-21.3). Lineage 2 accounted for 58.1% of MDR-TB cases from 2002 to 2011. Among immigrants, the predominant lineages corresponded to high prevalence lineages in the country of origin. In New Zealand-born individuals, Māori and NZ Europeans share the same predominant lineage, lineage 4, with a higher proportion of non-unique MIRU types observed in Māori cases. Lineage 3 was more prevalent in Māori than in NZ Europeans.

CONCLUSION: In New Zealand, M. tuberculosis complex phylogenetic lineage is associated with TB epidemiology in terms of ethnicity, country of origin and MDR-TB.