Fig. 1.

Positive interaction between ceftobiprole (BPR) and vancomycin (VAN) by Etest testing. A 0.5 McFarland standard of VISA PC3 (A and B) or VISA Mu50 (C and D) was inoculated on plain BHI agar plates (BHIA) and on BHIA plates containing 0.5 times the MIC of vancomycin (A and C) or 0.5 times the MIC of ceftobiprole (B and D). Etest strips of ceftobiprole (A and C) or vancomycin (B and D) were then placed on the plates, and the plates were incubated at 37°C for 24 h. A marked increase in zone size around Etest ceftobiprole and vancomycin strips was observed in the presence of the partner drug incorporated in the agar.