and intracellular inhibitory activities of nosiheptide against .

The high level of inherent drug resistance of makes the infection caused by it very difficult to be treated. The objective of this study was to evaluate the potential of nosiheptide (NOS) as a new drug candidate for treating infections. The microplate AlamarBlue assay was performed to determine the minimum inhibitory concentrations (MICs) of NOS for 28 reference strains of rapidly growing mycobacteria (RGM) and 77 clinical isolates of . Time-kill kinetic and post-antibiotic effect (PAE) of NOS against was evaluated. Its bactericidal activity against in macrophages was determined by an intracellular colony numerating assay. NOS manifested good activity against the reference strains of RGM and clinical isolates . The MICs of NOS against clinical isolates ranged from 0.0078 to 1 μg/ml, and the MIC and MIC were 0.125 μg/ml and 0.25 μg/ml, respectively. The pattern of growth and kill by NOS against was moderate with apparent concentration-dependent characteristics, and the PAE value of NOS was found to be ~6 h. Furthermore, NOS had low cell toxicity against the THP-1 cell line after 48 h of exposure (IC = 106.9 μM). At 4 μg/ml, NOS exhibited high intracellular bactericidal activity against reference strains with an inhibitory rate of 66.52% ± 1.51%, comparable with that of clarithromycin at 2 μg/ml. NOS showed suitable inhibitory activities against and in macrophages and could be a potential drug candidate to treat infection.