Genetic diversity of Mycobacterium tuberculosis isolated from tuberculosis patients in the Serengeti ecosystem in Tanzania

Abstract

SummaryThis study was part of a larger cross-sectional survey that was evaluating tuberculosis (TB) infection in humans, livestock and wildlife in the Serengeti ecosystem in Tanzania. The study aimed at evaluating the genetic diversity of Mycobacterium tuberculosis isolates from TB patients attending health facilities in the Serengeti ecosystem. DNA was extracted from 214 sputum cultures obtained from consecutively enrolled newly diagnosed untreated TB patients aged ≥18 years. Spacer oligonucleotide typing (spoligotyping) and Mycobacterium Interspersed Repetitive Units and Variable Number Tandem Repeat (MIRU-VNTR) were used to genotype M. tuberculosis to establish the circulating lineages. Of the214 M. tuberculosis isolates genotyped, 55 (25.7%) belonged to the Central Asian (CAS) family, 52 (24.3%) were T family (an ill-defined family), 38 (17.8%) belonged to the Latin American Mediterranean (LAM) family, 25 (11.7%) to the East-African Indian (EAI) family, 25 (11.7%) comprised of different unassigned (‘Serengeti’) strain families, while 8 (3.7%) belonged to the Beijing family. A minority group that included Haarlem, X, U and S altogether accounted for 11 (5.2%) of all genotypes. MIRU-VNTR typing produced diverse patterns within and between families indicative of unlinked transmission chains. We conclude that, in the Serengeti ecosystem only a few successful families predominate namely CAS, T, LAM and EAI families. Other types found in lower prevalence are Beijing, Haarlem, X, S and MANU. The Haarlem, EAI_Somalia, LAM3 and S/convergent and X2 subfamilies found in this study were not reported in previous studies in Tanzania.

Molecular characterization of Mycobacterium tuberculosis isolates from Tanga, Tanzania: First insight of MIRU-VNTR and microarray-based spoligotyping in a high burden country

“…Similar families have been reported in variable proportions in other countries bordering Tanzania [31e35], indicating a geographical widespread of this group of spoligotypes in the region. These findings are also in agreement with those of other studies conducted in Tanzania which reported the predominance of these families [21,36,37].…”

“…Strain families previously reported in Tanzania but not reported in this study include the Haarlem genotype [21,37] and the X genotypes [21,36e38]. We detected a high proportion of T family isolates as found in previous studies [21,37].…”

Isolation and Potential for Transmission ofMycobacterium bovisat Human-livestock-wildlife Interface of the Serengeti Ecosystem, Northern Tanzania

“…Of the 472 culture isolates from sputum samples, 214 (45.3%) M. tuberculosis strains were isolated and no M. bovis was recovered. Other results regarding M. tuberculosis have been reported separately (Mbugi et al., ).…”

New tuberculosis vaccine to support tuberculosis elimination

“…However, several studies found that the increase in MTBC virulence was associated with a decreased and/ or delayed inflammmatory response, possibly as a result of considerable bacterial proliferation in the early stages of infection and leading to increased MTBC virulence in the final stages. (5,6) The Bacille Calmette-Guérin (BCG) vaccine, which was developed almost 100 years ago and has been shown to prevent severe forms of TB in children, is still widely used. However, there is currently no vaccine that is effective in preventing TB disease in adults, either before or after exposure to TB infection.…”