Tuberculosis Case Study Ib

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Table 1 shows the antimicrobial resistance pattern for all antimicrobials agents used, and the MIC for rifampicin. Table 2 shows the relative quantification of the transcript levels for five rpfs in M. tuberculosis isolates, exposed to sub-MIC (MIC=128 mg/L) concentration of RIF.
Significant upregulation of relative expression (p< 0.05) was observed as follows: 7/15(46.66%), 5/15(33.33%), 9/15(60%), 10/15(66.66%) and 9/15(60%) in rpfA, rpfB, rpfC, rpfD and rpfE, respectively. Additionally, in three isolates (3/15; 20%) one rpf; four isolates (4/15; 26.66%) two rpf; five isolates (5/15; 33.33%) three rpf and three isolates (3/15; 20%) four rpf were upregulated, simultaneously. None of the isolates had all five rpf upregulated,
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Therefore, in the current study we investigated the effect of sub-MIC concentration of rifampin on Rpfs expression in resistant M. tuberculosis clinical isolates. It is noteworthy to mention that based on our analysis on H37Rv (a susceptible reference strain), no changes in the expression level of rpfs were detected (data not shown). This might indicate that very low MIC of RIF for this strain (and of course for other susceptible isolates), cannot affect rfp expression. Therefore, we have decided to work on MDR and RMR isolates with high MIC. Our results showed that rpfs could be overexpressed in some extent in the presence of sub-MIC concentration of rifampin in MDR and RMR M. tuberculosis, regardless of their antibiotic resistance pattern.
Some factors increase the risk of TB reactivation, and require screening and treatment for LTBI [18]. Our result highlights the potential risk of sub-MIC rifampin con¬centrations, as another risk factor in this regard. This issue may be more important in treatment of LTBI by rifampin monotherapy [19].
Rpf-dependent mycobacteria appear to underlie the difficulty we have in improving TB treatment, yet their presence appears to be driven, by both treatment and host factors [20]. It is noteworthy to mention that Rpf-dependent M. tuberculosis bacilli from sputum have been
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