Consistent with our tripartite proteomics data showing complementary action between macrophages and polymyxins in disarming the upregulation of (p)ppGpp synthetase/hydrolase SpoT (Fig 1A), a low concentration of polymyxin B (0.25 mg/L) in the THP-1-dMs infection system is sufficient to significantly reduce the survival of interacting spoT mutants compared to the wild-type strain (Fig 6B). Here, THEMIS is linked to infection.