The detection of synergy between meropenem and polymyxin B against meropenem-resistant Acinetobacter baumannii using Etest® and time-kill assay

Time-kill assay and Etest testing for synergy of meropenem (MER) (1× MIC) plus polymyxin B (1/4, 1/2, and 1× MIC) were performed against 8 genetically unique MER-resistant clinical Acinetobacter baumannii isolates. Time-kill assay demonstrated synergy for all isolates, whereas Etest showed synergy in 5 isolates and indifference in 3.