The Guinea-Bissau Family of Mycobacterium tuberculosis Complex Revisited

Abstract

The Guinea-Bissau family of strains is a unique group of the Mycobacterium tuberculosis complex that, although genotypically closely related, phenotypically demonstrates considerable heterogeneity. We have investigated 414 M. tuberculosis complex strains collected in Guinea-Bissau between 1989 and 2008 in order to further characterize the Guinea-Bissau family of strains. To determine the strain lineages present in the study sample, binary outcomes of spoligotyping were compared with spoligotypes existing in the international database SITVIT2. The major circulating M. tuberculosis clades ranked in the following order: AFRI (n = 195, 47.10%), Latin-American-Mediterranean (LAM) (n = 75, 18.12%), ill-defined T clade (n = 53, 12.8%), Haarlem (n = 37, 8.85%), East-African-Indian (EAI) (n = 25, 6.04%), Unknown (n = 12, 2.87%), Beijing (n = 7, 1.68%), X clade (n = 4, 0.96%), Manu (n = 4, 0.97%), CAS (n = 2, 0.48%). Two strains of the LAM clade isolated in 2007 belonged to the Cameroon family (SIT61). All AFRI isolates except one belonged to the Guinea-Bissau family, i.e. they have an AFRI_1 spoligotype pattern, they have a distinct RFLP pattern with low numbers of IS6110 insertions, and they lack the regions of difference RD7, RD8, RD9 and RD10, RD701 and RD702. This profile classifies the Guinea-Bissau family, irrespective of phenotypic biovar, as part of the M. africanum West African 2 lineage, or the AFRI_1 sublineage according to the spoligtyping nomenclature. Guinea-Bissau family strains display a variation of biochemical traits classically used to differentiate M. tuberculosis from M. bovis. Yet, the differential expression of these biochemical traits was not related to any genes so far investigated (narGHJI and pncA). Guinea-Bissau has the highest prevalence of M. africanum recorded in the African continent, and the Guinea-Bissau family shows a high phylogeographical specificity for Western Africa, with Guinea-Bissau being the epicenter. Trends over time however indicate that this family of strains is waning in most parts of Western Africa, including Guinea-Bissau (p = 0.048).

Mycobacterial Lineages Causing Pulmonary and Extrapulmonary Tuberculosis, Ethiopia

“…The frequency of M. bovis in persons in this study (0.4%) is similar to that found in other studies of human TB in Africa ( 11 ) and South and Central America ( 12 ), but much lower than that observed among selected populations in Tanzania (16%) ( 13 ), Ethiopia (17%) ( 14 ), and Mexico (28%) ( 15 ). These findings indicate that the overall contribution of M. bovis to human TB is minor but greater in specific areas.…”

Consequences of genomic diversity in Mycobacterium tuberculosis

“…However, three studies have reported decreasing prevalence of M. africanum (i.e. Lineage 5 and 6) in Cameroon, Guinea-Bissau and Burkina Faso [204–206], supporting of the lower “virulence” of the “ancestral” lineages. Therefore, although sub-lineage differences might obscure general patterns, taken together, these studies support the view that on average “modern” MTBC lineages are more transmissible than other strains.…”

Mycobacterium tuberculosis: ecology and evolution of a human bacterium

“…Moreover, these lineages have been generally associated with the recent transmission of TB and with epidemics. This is true particularly for the Beijing family, which is ubiquitous and in the process of invading many countries, such as Vietnam (Nguyen et al, 2012), and also for the LAM family, which is spreading in Africa (Godreuil et al, 2007c;Groenheit et al, 2011).…”