The most frequent Mycobacterium tuberculosis complex families in mali (2006–2016) based on spoligotyping

Abstract

Objective To identify strains of Mycobacterium tuberculosis complex (MTBc) circulating in Bamako region during the past 10 years. Materials and Methods From 2006 to 2016, we conducted a cross-sectional study to identify with spoligotyping, clinical isolates from tuberculosis (TB)-infected patients at different stages of their treatments in Bamako, Mali. Results Among the 904 suspected TB patients included in the study and thereafter tested in our BSL-3 laboratory, 492 (54.4%) had MTBc and therefore underwent spoligotyping. Overall, three subspecies, i.e., MTB T1 (31.9%) and MTB LAM10 (15.3%) from lineage 4 and M. africanum 2 (16.8%) from lineage 6 were the leading causes of TB in Bamako region during the past 10 years. Other spoligotypes such as MTB T3, MTB Haarlem 2, MTB EAI3, and MTB family 33 were also commonly seen from 2010 to 2016. Conclusion This study showed a high genetic diversity of strains isolated in Bamako region and highlights that M. tuberculosis T1 strain was the most prevalent. Furthermore, the data indicate an increasing proportion of primary drug resistance overtime in Bamako.

Mycobacterium africanum (Lineage 6) shows slower sputum smear conversion on tuberculosis treatment than Mycobacterium tuberculosis (Lineage 4) in Bamako, Mali

“…In this study we estimated a relatively unbiased population structure of the MTBc in consecutive smear positive new adult TB patients from Bamako district, and identified differential smear conversion by MTBc lineage. Our prevalence estimates of the different MTBc lineages correspond with earlier and smaller studies based on convenience sampling, with predominance of L4 (57%) and L6 (22.9%), while L1, L2, L3, and L5 are all present at less than five percent[4,10]. Counter to our hypothesis that L6 would respond better to TB treatment, we found that patients diseased with L6 rather experienced slower smear conversion than L4, not only with AR staining- which will stain dead bacilli too- but also with FDA vital stain microscopy.…”

“…Most studies on the MTBc population structure in the West African region were based on convenience sampling at referral centers, rather than sampling representative of the general TB population[9,10]. This potential for selection bias, combined with the higher risk for L6 to be missed in culture, has complicated estimates of the prevalence of L6 over time[10,11].…”

“…Most studies on the MTBc population structure in the West African region were based on convenience sampling at referral centers, rather than sampling representative of the general TB population[9,10]. This potential for selection bias, combined with the higher risk for L6 to be missed in culture, has complicated estimates of the prevalence of L6 over time[10,11]. In several countries, L6 appears to be declining, while in others its prevalence appears to be stable, with most recent estimates for Mali suggesting a prevalence of between 21 and 33.3% in 1994, 27.8% in 2012, and 16.8% between 2008 and 2016 in Mali[4,10,12].…”

“…M . africanum (L6) is underrepresented among retreatment patients and those with drug resistance[3,4,10,14]. However, some studies have found that the immunological recovery of patients treated for L6 lags behind those treated for L4[15,16].…”

Patients infected with Mycobacterium africanum versus Mycobacterium tuberculosis possess distinct intestinal microbiota

“…We estimated, a priori, that 20 participants each would be needed in the MAF and MTB groups to achieve 80% power with a two-sided significant level (α) of 0.05, and at a 95% confidence level. We assumed based on previous studies [4,32], that 42% of patients are exposed/likely to be MAF-infected, with an Odds Ratio of 14 (confidence interval: 11-17), a risk/prevalence ratio of 8.5 and a risk/prevalence difference of 37.…”