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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.

Potato soft rot, caused by Bacillus pumilus Od23, greatly affect potato tuber quality in storage and cultivars of Mali and indicated that it can affect all potato cultivars. Bacteria isolated from soil rhizosphere samples of healthy Malian indigenous trees were screened for their antagonistic effect against this pathogen. Three actinomycetes isolates (RoN, G1P, and N1F) were the most effective microbioagents in suppressing the growth of the pathogen. The biological control essay showed the possibility of controlling potato soft rot by these three actinomycetes isolates under conservation conditions. These treatments significantly decreased soft rot compared with the untreated potato tuber slices. The microbiological control results of this study suggest that the actinomycetes isolates RoN, G1P and and J1N are effective microbioagents in controlling soft rot of potato and could be considered as promising alternative to chemical products.