Etest synergy testing of clinical isolates of Staphylococcus aureus demonstrating heterogeneous resistance to vancomycin

In search for potential synergistic antimicrobial combinations against Staphylococcus aureus isolates, which display heterogeneous resistance to vancomycin, we evaluated the activities of 21 various combinations involving ampicillin/sulbactam, daptomycin, gentamicin, linezolid, quinupristin/dalfopristin, rifampin, and vancomycin by Etest and time-kill methods. A number of combinations demonstrated either synergistic or additive effects against hGISA SA 118 and GISA SA 179. Agreement between the Etest and time-kill methods for detecting antimicrobial synergy ranged from 66.6% to 71.4%. The Etest method appears promising, and further investigations are warranted. (c) 2006 Elsevier Inc. All rights reserved.