This study indicates a low level of primary drug resistance in Bamako, affirms the importance of using correct drug regimens, and suggests that the MTB T1 strain may be associated with the development of resistance.

ObjectiveAncestral M. tuberculosis complex lineages such as M. africanum are underrepresented among retreatment patients and those with drug resistance. To test the hypothesis that they respond faster to TB treatment, we determined the rate of smear conversion of new pulmonary tuberculosis patients in Bamako, Mali by the main MTBc lineages.MethodsBetween 2015 and 2017, we conducted a prospective cohort study of new smear positive pulmonary tuberculosis patients in Bamako. Confirmed MTBc isolates underwent genotyping by spoligotyping for lineage classification. Patients were followed at 1 month (M), 2M and 5M to measure smear conversion in auramine (AR) and Fluorescein DiAcetate (FDA) vital stain microscopy.ResultAll the first six human MTBc lineages were represented in the population, plus M. bovis in 0.8% of the patients. The most widely represented lineage was the modern Euro-American lineage (L) 4, 57%, predominantly the T family, followed by L6 (M. africanum type 2) in 22.9%. Ancestral lineages 1, 5, 6 and M. bovis combined amounted to 28.8%. Excluding 25 patients with rifampicin resistance, smear conversion, both by AR and FDA, occurred later in L6 compared to L4 (HR 0.80 (95% CI 0.66–0.97) for AR, and HR 0.81 (95%CI 0.68–0.97) for FDA). In addition we found that HIV negative status, higher BMI at day 0, and patients with smear grade at baseline ≤ 1+ were associated with earlier smear conversion.ConclusionThe six major human lineages of the MTBc all circulate in Bamako. Counter to our hypothesis, we found that patients diseased with modern M. tuberculosis complex L4 respond faster to TB treatment than those with M. africanum L6.

SUMMARY The global spread of Nontuberculous Mycobacteria (NTM) may be due to HIV/AIDS and other environmental factors. The symptoms of NTM and tuberculosis (TB) disease are indistinguishable, but their treatments are different. Lack of research on the epidemiology of NTM infections has led to underestimation of its prevalence within TB endemic countries. This study was design to determine the prevalence and clinical characteristics of pulmonary NTM in Bamako. A cross-sectional study which include 439 suspected cases of pulmonary TB. From 2016 to 2013 a total of 332 (76%) were confirmed to have sputum culture positive for Mycobacteria.The prevalence of NTM infection was 9.3% of our study population and 12.3% of culture positive patients.The seroprevalence of HIV in NTM group was 17.1%. Patients who weighed less than 55 kg and had TB symptoms other than cough were also significantly more likely to have disease due to NTM as compared to those with TB diease who were significantly more likely to have cough and weigh more than 55 kg (OR: 0.05 [CI: 0.02 – 0.13] and OR: 0.32 [CI: 0.11–0.93] respectively). NTM disease burden in Bamako was substantial and diagnostic algorithms for pulmonary diseae in TB endemic countries should consider the impact of NTM.

Background: While, bacteria resistance mutations can affect competitive fitness, given our multidrug-resistant (MDR) prevalence, we conducted this study to determine the impact of MDR on the competitive fitness of Mycobacterium tuberculosis (MTB) complex MDR strains. We conducted a cross-sectional study at the University Clinical Research Center (UCRC) from January to December 2017. New TB patients over aged of 18 were recruited at University teaching hospital and health reference centers of Bamako in USTTB Ethical committee approved protocols. Methods: MDR and drug-susceptible (wild-type [WT]) MTB strains (T1 and Beijing) and MTB H37Rv were competed on solid media in UCRC’s Tuberculosis Laboratory. Competitive and individual cultures were incubated for 14 days at 37°C with 7% CO2. Number of generation, generation time, and relative competitive fitness (W) of the strains were calculated. Data were analyzed with Epi-Info 7.1.5.2 software (CDC). P value was considered significant when it was <0.05. Scientific calculator (CS-82TL) was used for competitive fitness parameters calculations. Results: We performed 24 competitive cultures and 10 individual cultures. In individual cultures, strains’ generation number was for Beijing (WT: 4.60 and mutant MR: 4.40), T1 (WT: 2.69 and MR: 2.37), and H37Rv: 2.91. Generation number of WT strains was less than those of MDR strains in both individual and competitive culture. Relative competitive fitness was below 1 (W˂1) in 83.3%. Conclusion: MDR strains were less competitive than WT strains in 83.3% of cases. Resistant mutation impacts bacteria fitness.

Objectives In Mali early detection and treatment of multidrug resistance tuberculosis (MDR-TB) are still challenging due to cost, time and/or complexity associated with regular tests. Microscopic Observation Drug Susceptibility (MODS) is a low-cost assay validated by WHO in 2010. It is a liquid culture based assay to detect the “cording” characteristic of Mycobacterium tuberculosis complex (MTBc) and to assess susceptibility to both isoniazid and rifampicin defining MDR-TB. In this study we aimed to evaluate the performance of MODS as diagnostic tool compared to a validated method, the MGIT/AST/SIRE. Methods and Results Between January 2010 and October 2015, we included 98 suspected TB patients in an observational cohort study. The sensitivity and specificity of MODS assay for detecting TB were respectively 94.12% and 85.71% compared to the reference MGIT/7H11 culture, with a Cohen Kappa coefficient of 0.78 [95% CI: 0.517-1.043]. The median time to culture positivity for MODS assay and MGIT (plus interquartile range, IQR) was respectively eight days [IQR, 5-11] and six days [IQR, 5-6]. In detecting MDR-TB patients, the sensitivity and specificity of MODS assay were respectively 100% and 95.92%. The positive predictive value and negative predictive values were respectively 66.7% and 100%. The median turnaround time for obtaining MDR-TB results using MODS assay and MGIT/AST/SIRE was respectively nine days and 35 days. Thus, the MODS assay rapidly identifies MDR-TB in Mali than the MGIT/AST/SIRE. Conclusion As an easy, simple, fast and affordable method, the MODS assay could significantly improve the management of tuberculosis.