Biochem/physiol Actions Mode of Action: Inhibits protein synthesis (elongation) by preventing binding of aminoacyl-tRNA to the 30S subunit. Antimicrobial spectrum: Gram-negative and Gram-positive bacteria.Mode of Resistance: Loss of cell wall permeability. Mode of Action: inhbit bacterial protein synthesis elongation at the level of aminoacyl-tRNA binding to the 30S ribosome. Antimicrobial spectrum: Gram-negative and Gram-positive bacteria. Mode of Resistance: Loss of cell wall permeability.