Evaluation of antimycobacterial activity of medicinal plants used by Malian traditional medicine practitioners to treat tuberculosis

Global Tuberculosis (TB) control is facing major challenges such as occurrence of multidrug-resistant (MDR) and extensively drug-resistant tuberculosis (XDR). The current TB drugs are getting less effective and associated with side effects limiting their use, especially with MDR and XDR infected patients. In Mali, many medicinal plants are used against various diseases including bacterial infections. The study aimed at studying the antimycobacterial activities of 60 extracts from 22 Malian medicinal. The antibacterial activity against Mycobacterium tuberculosis H37Rv was assessed employing micro-broth dilution method. Out of 60 extracts evaluated, eleven from nine different plants were found to be active against H37Rv strain. The minimal inhibitory concentrations (MICs) ranked from 125 μg/mL to 1250 μg/mL. The most active extracts (125 μg/mL) were represented by ethanolic extract of Saba senegalensis and Vitellaria paradoxa leaves, dichloromethane extract of Cola cordifolia leaves, Strychnos spinosa and Ximenia Americana roots. Ethanolic extract of Zizyphus mauritiana, Guiera senegalensis and methanolic extract of Anthocleista djalonensis also prevented the growth of H37Rv at 250 μg/mL. The results suggest that Saba senegalensis, Vitellaria paradoxa, Cola cordifolia, Strychnos spinosa and Ximenia Americana could be potential sources of antimycobacterial molecule

Evolution of Mycobacterium tuberculosis complex lineages and their role in an emerging threat of multidrug resistant tuberculosis in Bamako, Mali

In recent years Bamako has been faced with an emerging threat from multidrug resistant TB (MDR-TB). Whole genome sequence analysis was performed on a subset of 76 isolates from a total of 208 isolates recovered from tuberculosis patients in Bamako, Mali between 2006 and 2012. Among the 76 patients, 61(80.3%) new cases and 15(19.7%) retreatment cases, 12 (16%) were infected by MDR-TB. The dominant lineage was the Euro-American lineage, Lineage 4. Within Lineage 4, the Cameroon genotype was the most prevalent genotype (n = 20, 26%), followed by the Ghana genotype (n = 16, 21%). A sub-clade of the Cameroon genotype, which emerged ~22 years ago was likely to be involved in community transmission. A sub-clade of the Ghana genotype that arose approximately 30 years ago was an important cause of MDR-TB in Bamako. The Ghana genotype isolates appeared more likely to be MDR than other genotypes after controlling for treatment history. We identified a clade of four related Beijing isolates that included one MDR-TB isolate. It is a major concern to find the Cameroon and Ghana genotypes involved in community transmission and MDR-TB respectively. The presence of the Beijing genotype in Bamako remains worrying, given its high transmissibility and virulence

Epidémiologie et recherche sur la tuberculose au Mali: Etat des lieux

La tuberculose reste un problème de santé publique au Mali malgré les bons scores enregistrés ces dernières années aussi bien dans la lutte que dans la recherche contre la maladie. Le nombre de cas est resté globalement stable au cours des dernières années, mais l’augmentation des cas de résistances attire de plus en plus l’attention et demande une réponse plus rigoureuse de la part des décideurs. Les recherches menées ont permis d’identifier les souches tuberculeuses circulantes au Mali, les profils de résistances et les mycobactérioses atypiques qui posent un problème de diagnostic différentiel avec la tuberculose. Les recherches ont permis aussi de mieux comprendre l’immunologie de la maladie, notamment le rôle des cellules lymphocytaires au cours de la coinfection avec le VIH et du traitement antituberculeux. Tous ces efforts doivent être renforcés pour le long terme afin de venir à bout de la maladie

Whole Genome Sequencing of <i>Mycobacterium africanum</i> Strains from Mali Provides Insights into the Mechanisms of Geographic Restriction

<div><p>Background</p><p><i>Mycobacterium africanum</i>, made up of lineages 5 and 6 within the <i>Mycobacterium tuberculosis</i> complex (MTC), causes up to half of all tuberculosis cases in West Africa, but is rarely found outside of this region. The reasons for this geographical restriction remain unknown. Possible reasons include a geographically restricted animal reservoir, a unique preference for hosts of West African ethnicity, and an inability to compete with other lineages outside of West Africa. These latter two hypotheses could be caused by loss of fitness or altered interactions with the host immune system.</p><p>Methodology/Principal Findings</p><p>We sequenced 92 MTC clinical isolates from Mali, including two lineage 5 and 24 lineage 6 strains. Our genome sequencing assembly, alignment, phylogeny and average nucleotide identity analyses enabled us to identify features that typify lineages 5 and 6 and made clear that these lineages do not constitute a distinct species within the MTC. We found that in Mali, lineage 6 and lineage 4 strains have similar levels of diversity and evolve drug resistance through similar mechanisms. In the process, we identified a putative novel streptomycin resistance mutation. In addition, we found evidence of person-to-person transmission of lineage 6 isolates and showed that lineage 6 is not enriched for mutations in virulence-associated genes.</p><p>Conclusions</p><p>This is the largest collection of lineage 5 and 6 whole genome sequences to date, and our assembly and alignment data provide valuable insights into what distinguishes these lineages from other MTC lineages. Lineages 5 and 6 do not appear to be geographically restricted due to an inability to transmit between West African hosts or to an elevated number of mutations in virulence-associated genes. However, lineage-specific mutations, such as mutations in cell wall structure, secretion systems and cofactor biosynthesis, provide alternative mechanisms that may lead to host specificity.</p></div

Average nucleotide identity (ANI) analysis indicates <i>M</i>. <i>africanum</i> and <i>M</i>. <i>tuberculosis</i> are not separate species.

<p>A) ANI values when comparing <i>M</i>. <i>africanum</i> and <i>M</i>. <i>tuberculosis</i> do not cross the ANI species threshold of 94–95%. In fact, this comparison shows that the distribution of <i>M</i>. <i>africanum</i>/<i>M</i>. <i>tuberculosis</i> comparisons (red) overlaps that of inter-lineage <i>M</i>. <i>tuberculosis</i> comparisons (purple), indicating that <i>M</i>. <i>africanum</i> should be considered another lineage of <i>M</i>. <i>tuberculosis</i>. B) Similarly, ANI values when comparing <i>M</i>. <i>bovis</i> and <i>M</i>. <i>tuberculosis</i> also overlap with inter-lineage <i>M</i>. <i>tuberculosis</i>, and indicate that <i>M</i>. <i>bovis</i> should also be considered another lineage of <i>M</i>. <i>tuberculosis</i>. C) ANI values comparing <i>M</i>. <i>africanum</i> and <i>M</i>. <i>bovis</i> (pink) also overlap inter-lineage <i>M</i>. <i>tuberculosis</i> comparisons (green).</p

Percentage of lineage-specific mutations in virulence associated genes.

<p>A) Percentage of lineage-specific mutations in coding sequences of the genes in each category. Sassetti virulence genes are genes that were identified in [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004332#pntd.0004332.ref066" target="_blank">66</a>] as being required for virulence in mice. Sassetti essential and slow growth genes were identified by Sassetti et al. under <i>in vitro</i> conditions using TraSH [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004332#pntd.0004332.ref065" target="_blank">65</a>]. Rengarajan macrophage genes were identified by Rengarajan et al. as being required for growth in macrophages [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004332#pntd.0004332.ref067" target="_blank">67</a>]. Comas antigen genes were genes identified by Comas et al. as containing T cell epitopes [<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0004332#pntd.0004332.ref004" target="_blank">4</a>]. The color of the bar indicates type of mutation. B) Percentage of lineage-specific pseudogenes falling into the above defined categories. Missing categories had no pseudogenes in any lineage. Lineage is indicated by the number below each bar, while ‘af’ indicates mutations found in both lineages 5 and 6 (both <i>M</i>. <i>africanum</i> lineages).</p

Screening new tuberculosis patients in Mali for rifampicin resistance at 2 months

Objective/background: The recent call for universal drug susceptibility testing (DST) for all tuberculosis (TB) patients will be difficult to meet in settings where Xpert rollout is limited, such as low prevalence of HIV and Multi-drug Resistant Tuberculosis (MDR) settings. As recommended by World Health Organization (WHO) guidelines, the success of TB treatment is measured by Ziehl–Neelsen (ZN) microscopy or auramine–rhodamine fluorescent microscopy (FM) on sputum, in which conversion to negative smear at 2 months (M) is an important predictor of treatment success, defined as a negative smear at 5M. The sputum smear that fails to convert to negative at 5M are screened for rifampicin resistance. We tested in a prospective study whether an early screen for rifampicin resistance, based on FM results at 2M, could detect MDR patients early, rather than screening all patients with GeneXpert MTB/Rif at baseline. Methods: Between February 2015 and August 2016, we enrolled new TB patients in an IRB-approved prospective cohort study at four health centers in Bamako district. Fresh sputum samples were collected at 2M and 5M to measure FM smear conversion. Patients who failed to show a decline in FM positivity at 2M (moderate or many Acid Fast Bacilli (AFB)) had their sputum tested in GeneXpert to detect rifampicin resistance. Patients who had any AFB seen at 5M were also tested using GeneXpert. Results: Of the 570 patients who were enrolled in the study, 22 (3.8%) died and 27 (4.7%) were lost to follow-up. The prevalence of HIV and TB coinfection was 12.4%, and 65.6% of the patients were male. At 2M, 32 out of 429 patients still had moderate or many AFBs in FM, and were screened by Xpert, of whom 5 (15.6%) tested rifampicin-resistant and were referred for MDR treatment. Of the 310 patients who completed 5M of treatment, 35 (11.3%) met the definition of failure (few or moderate AFB in FM) and had their sputum tested in Xpert; moreover, four (11.4%) demonstrated rifampicin resistance. In total, 67 (21.6% of 310) patients were screened by Xpert, of whom nine were detected to have MDR (or 13.4% of those screened). Conclusion: Although we cannot exclude additional MDR patients having been missed by our screening strategy, our screening algorithm at 2M detected five out of nine MDR patients. Detecting patients at 2M allowed for earlier referral, and potentially less acquired drug resistance and lower mortality. This strategy may be advantageous while awaiting further rollout of Xpert machines that will permit universal DST

Relationship between patient sex and anatomical sites of extrapulmonary tuberculosis in Mali

Background: Contribution of host factors in mediating susceptibility to extrapulmonary tuberculosis is not well understood. Objective: To examine the influence of patient sex on anatomical localization of extrapulmonary tuberculosis. Methods: We conducted a retrospective cross-sectional study in Mali, West Africa. Hospital records of 1,304 suspected cases of extrapulmonary tuberculosis, available in TB Registry of a tertiary tuberculosis referral center from 2019 to 2021, were examined. Results: A total of 1,012 (77.6%) were confirmed to have extrapulmonary tuberculosis with a male to female ratio of 1.59:1. Four clinical forms of EPTB predominated, namely pleural (40.4%), osteoarticular (29.8%), lymph node (12.5%), and abdominal TB (10.3%). We found sex-based differences in anatomical localization of extrapulmonary tuberculosis, with males more likely than females to have pleural TB (OR: 1.51; 95% CI [1.16 to 1.98]). Conversely, being male was associated with 43% and 41% lower odds of having lymph node and abdominal TB, respectively (OR: 0.57 and 0.59). Conclusion: Anatomical sites of extrapulmonary tuberculosis differ by sex with pleural TB being associated with male sex while lymph node and abdominal TB are predominately associated with female sex. Future studies are warranted to understand the role of sex in mediating anatomical site preference of tuberculosis