First Molecular Epidemiology Study of Mycobacterium tuberculosis in Kiribati

Abstract

Tuberculosis incidence rates in Kiribati are among the highest in the Western Pacific Region, however the genetic diversity of circulating Mycobacterium tuberculosis complex strains (MTBC) and transmission dynamics are unknown. Here, we analysed MTBC strains isolated from culture positive pulmonary tuberculosis (TB) cases from the main TB referral centre between November 2007 and October 2009. Strain genotyping (IS6110 typing, spoligotyping, 24-loci MIRU-VNTR and SNP typing) was performed and demographic information collected. Among 73 MTBC strains analysed, we identified seven phylogenetic lineages, dominated by Beijing strains (49%). Beijing strains were further differentiated in two main branches, Beijing-A (n = 8) and -B (n = 28), that show distinct genotyping patterns and are characterized by specific deletion profiles (Beijing A: only RD105, RD207 deleted; Beijing B: RD150 and RD181 additionally deleted). Many Kiribati strains (59% based on IS6110 typing of all strains) occurred in clusters, suggesting ongoing local transmission. Beijing-B strains and over-crowded living conditions were associated with strain clustering (likely recent transmission), however little evidence of anti-tuberculous drug resistance was observed. We suggest enhanced case finding amongst close contacts and continued supervised treatment of all identified cases using standard first-line drugs to reduce TB burden in Kiribati. Beijing strains can be subdivided in different principle branches that might be associated with differential spreading patterns in the population.

Mycobacterium tuberculosis phylogeography in the context of human migration and pathogen's pathobiology: Insights from Beijing and Ural families

“…The data on Oceania are available for the adjacent areas in Australia (Queensland, Torres Straight) and Papua New Guinea, PNG (Western Province, Torres Straight) [43,44] and for the Kiribati islands [25]. Australian sample included strains of both M11 and other "Asian" types; as I hypothesized previously, the penetration of Beijing strains to Australia may have started since the end of the nineteenth century following the discovery of gold [33].…”

Diversity of Mycobacterium tuberculosis lineages in French Polynesia

“…24 In the PICTs, different percentages of the predominant lineage combined with the distribution of other lineages are in accordance with the high diversity among Pacific Islands in terms of population (Polynesian, Melanesian, Micronesia), country size, medical care capacities, socioeconomical conditions, lack of global exchanges (Frenchand English-spoken countries, >1200 languages), and the large geographic area (22 Pacific Island Countries and Territories; approximately 25,000 islands and islets). The difference in the prevalence is principally recorded for the Beijing isolate, which represented 49% of the strains in Kiribati, 7 2.9% in French Polynesia, and 21.9% in Papua New Guinea. 8 Epidemiology is different in the Western Pacific (South East Asian) region in which the predominant lineage is the East AfricaneIndian lineage with 59% of the strains in Cambodia 5 and 50.7% in Vietnam (East AfricaneIndianeVietnam genotype).…”

“…21,22 In Egypt, the high proportion of this ancestral lineage led the authors to suggest that the Manu lineage could be the missing link between modern and ancestral lineages of M. tuberculosis. 23 In the PICTs, molecular epidemiological data about M. tuberculosis are available for Kiribati (Micronesia subregion), 7 Papua New Guinea (Melanesia subregion), 8 and French Polynesia (Polynesia subregion, from this study). In Figure 3.…”

“…The similarity option of the MIRU-VNTRplus website (http://www.miru-vntrplus.org) confirmed isolate MT22 as a Beijing group B (East Asian lineage). 7 Tree-based analysis was adopted to enable the assignment of the other isolates to lineages. 19 Eleven isolates were identified as members of the S lineage, one of the LAM lineage, nine of the Haarlem lineage, and eight of the X lineage.…”

“…4 Concerning the genetic diversity of M. tuberculosis in the Pacific region, data are principally available for the Western Pacific region. 5,6 Because there are no laboratory tools, very little is known about the molecular epidemiology of M. tuberculosis in the PICTs, except for studies conducted in Kiribati (Micronesia) 7 and Papua New Guinea (Melanesia). 8 Molecular tools have been proven to be useful in obtaining a better understanding of TB epidemiology.…”