Time-kill curves demonstrating synergistic killing of COL plus TZB against Acinetobacter baumannii. (A) Kill curve of static sub-MICs against A. baumannii strain AB5075 (dashed line, growth control; black circles, COL 0.4 mg/liter; black squares, TAZ 20 mg/liter; black triangles, COL 0.4 plus TAZ 20 mg/liter). (B) Simulated in vitro PK/PD modeling against another clinical A. baumannii strain (dashed line, growth control; black squares, COL 2.5 mg/kg/day; black triangles, COL 5 mg/kg/day; white squares, COL 2.5 mg/kg/day plus TAZ 500 mg q8h; white triangles, COL 5 mg/kg/day plus TAZ 500 mg q8h).