Observed (symbols) and model fitted (lines) viable counts for the dynamic in vitro PK/PD model experiments with colistin or meropenem alone and the combination against A. baumannii ATCC 19606 (A), AB1845 (B), and AB2092 (C). Meropenem dose of 0.5 g is infused for 0.5 h, and 1 or 2 g is for 3-h infusion. CST, colistin; MEM, meropenem.