Recombinant M. Tuberculosis Des Protein

Objectives: Amikacin is the only second-line injectable antituberculosis (anti-TB) drug still recommended for multidrug-resistant tuberculosis (MDR-TB) treatment when a short MDR-TB regimen is designed. Mutations in rrs and eis are reported to be associated with resistance to amikacin. In this study, we investigated the incidence of rrs, eis, tap and whiB7 mutations in amikacin-resistant Mycobacterium tuberculosis clinical isolates to find the proportion of different mutations related to amikacin resistance. Methods: A total of 395 clinical isolates of M. tuberculosis were used for phenotypic drug susceptibility testing (DST) to 10 drugs with the Lowenstein-Jensen (L-J) method. We sequenced rrs, eis, tap and whiB7 genes in 178 M. tuberculosis clinical isolates (89 amikacin-resistant isolates and 89 of 306 amikacin-susceptible isolates). Results: Our data showed that 22.53% (89/395) M. tuberculosis clinical isolates were resistant to amikacin. Of the 89 amikacin-resistant isolates, 89.89% (80/89) were MDR-TB, of which 12.36% (11/89) were preextensively drug-resistant TB (pre-XDR-TB) and 77.53% (69/89) were XDR-TB. The rrs mutations were found in 82% (73/89) in amikacin-resistant M. tuberculosis clinical isolates. The A1401G alteration in the rrs gene was the most dominant mutation (80.90%; 72/89). Five mutations were detected as new in rrs, tap and whiB7. Notably, 13.48% (12/89) amikacin-resistant isolates had no known mutation in these genes. Conclusions: Our data reveal that the rrs mutation is a predominant molecular marker of amikacin resistance in southern China. Analysis of the rrs gene mutations will significantly reduce the time and cost to diagnose amikacin resistance in TB patients. Other unknown amikacin resistance mechanism(s) exist. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.

Apoptotic and inflammatory pathways play important roles in Mycobacterium tuberculosis-infected macrophages. Sirt1 is a member of the deacetylase family that is known to promote apoptosis resistance in mammalian cells and was recently reported to regulate mycobacterial immunopathogenesis via inflammatory responses. However, the apoptotic role of Sirt1 in the process of M. tuberculosis infection remains unclear. With the help of mouse peritoneal macrophage samples, we have shown that resveratrol, a Sirt1 activator, inhibited M. tuberculosisinduced apoptosis in peritoneal macrophages. Further, we found that Sirt1 activation prompted M. tuberculosis induced GSK3 beta phosphorylation. Further investigation into the possible mechanisms of action showed that Sirt1 directly interacted with GSK3 beta and enhanced GSK3 beta phosphorylation by promoting its deacetylation. Sirt1 activation inhibited M. tuberculosis growth. Thus, it seemed that Sirt1 acted as a novel regulator of apoptosis signaling in M. tuberculosis infection via its direct effects on GSK3 beta. Sirt1 may therefore be a new candidate for the prevention and treatment of tuberculosis.