2.A.38.4.6
K⁺ uptake system, KtrABD.  S. aureus devoid of the Ktr system became sensitive to hyperosmotic conditions, exhibited a hyperpolarized plasma membrane, and increased susceptibility to aminoglycoside antibiotics and cationic antimicrobials. In contrast to other organisms, the S. aureus Ktr system was shown to be important for low-K+ growth under alkaline conditions but played only a minor role in neutral and acidic conditions. In a mouse competitive index model of bacteraemia, the ktrA mutant was significantly outcompeted by the parental strain (Gries et al. 2013).