In-vitro activity of vancomycin, teicoplanin, daptomycin, ramoplanin, MDL 62873 and other agents against staphylococci, enterococci and Clostridium difficile.

The minimum inhibitory concentrations (MICs) of different antibiotics were determined by a broth microdilution method for staphylococci, enterococci and Clostridium difficile. The antimicrobial agents tested were vancomycin, teicoplanin, daptomycin, ramoplanin, MDL 62873, rifampicin and piperacillin, the latter limited to enterococci. In terms of MIC90S, daptomycin (0.89 mg/l). MDL 62873 (0.99 mg/l), and teicoplanin (1.50 mg/l) were found to be highly active against methicillin-resistant Staphylococcus aureus (MRSA). Daptomycin (MIC90 0.48 mg/l), MDL 62873 (0.95 mg/l) and ramoplanin (1.45 mg/l) were the most active drugs against methicillin-resistant S. epidermidis (MRSE). Teicoplanin (MIC90 0.45 mg/l) was the most active agent against enterococci, followed by MDL 62873 (0.65 mg/l) and daptomycin (1.60 mg/l). MDL 62873 gave the lowest MIC90 (0.17 mg/l) for C. difficile. Teicoplanin (MIC90 0.42 mg/l), daptomycin (0.87 mg/l) and ramoplanin (0.98 mg/l) were also very active. Our results indicate that teicoplanin, daptomycin, ramoplanin and MDL 62873, a teicoplanin derivative, are potentially effective alternative antibiotics for treatment of infections caused by staphylococci, enterococci and C. difficile.