Ability of CEM-102 (sodium fusidate), Linezolid, Daptomycin to Select Resistant S. aureus Mutants at Steady-state Plasma Levels

Revised) Materials and Methods (cont.) Dr. Peter C. Appelbaum Department of Pathology Hershey Medical Center 500 University Drive Hershey, PA 17033 Phone: (717) 531-5113 E-mail: [email protected] Background: We tested the ability of CEM-102 (sodium fusidate), an established antistaphylococcal drug, to select for resistant clones of 8 methicillin-resistant and 1 methicillin-susceptible S. aureus strains of varying resistance phenotypes compared to linezolid and daptomycin using starting concentrations equivalent to each drug’s steadystate plasma concentration and different conditions. Methods: The 8 MRSA were 3 CA-MRSA, 2 HA-MRSA, 1 hVISA, 1 VISA, 1 VRSA. In initial 12 h selections, each drug at steady-state concentration (CEM-102, 80 μg/mL; linezolid, 6.4 μg/mL; daptomycin 6 7 μg/mL): was tested against 0 5 or 2 0 McFarland of inoculum in Mueller Hinton broth (MHB) Table 1. Characterization of strains and MICs for all drugs used in the study. STRAIN HMC# PHENOTYPE LOCATION SOURCES MIC (μg/mL) CEM-102 DAPTOMYCIN LINEZOLID ICAAC 2010 E-1557