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

Tsuji, Brian T.; Rybak, Michael J.

doi:10.1016/j.diagmicrobio.2005.08.014

« Previous Next »Diagnostic Microbiology & Infectious Disease
Volume 54, Issue 1 , Pages 73-77, January 2006

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

Brian T. Tsuji
- Anti-Infective Research Laboratory, Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA
- Department of Pharmacy Services, Detroit Receiving Hospital and University Health Center, Detroit, MI 48201, USA
- Current address: School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, NY 14260, USA.
Michael J. Rybak
- Anti-Infective Research Laboratory, Department of Pharmacy Practice, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA
- Department of Pharmacy Services, Detroit Receiving Hospital and University Health Center, Detroit, MI 48201, USA
- School of Medicine, Wayne State University, Detroit, MI 48201, USA
- Corresponding author. Anti-Infective Research Laboratory, Department of Pharmacy Practice 4148, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Avenue, Detroit, MI 48201. Tel.: +1-313-993-4673; fax: +1-313-577-8915.

Received 14 June 2005; received in revised form 26 August 2005; accepted 29 August 2005.

Abstract

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 SA118 and GISA SA179. 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.

Keywords: Etest, Synergy heterogeneous resistant S. aureus, Daptomycin, Linezolid, Quinupristin/dalfopristin, Rifampin, Vancomycin, Ampicillin/sulbactam, Gentamicin