Comparative activities of daptomycin and several agents against staphylococcal blood isolates. Glycopeptide tolerance

The activity of daptomycin was evaluated against 702 staphylococcal blood isolates (316 methicillin-susceptible Staphylococcus aureus, 187 methicillin-resistant S. aureus [MRSA], and 199 coagulase-negative staphylococci [CoNS]) collected in 41 Spanish hospitals. Glycopeptide tolerance and the incidence of heterogeneous glycopeptide-intermediate (hGISA) isolates were also examined. Vancomycin MICs determined by the Etest were compared with those obtained by the reference broth microdilution method. Daptomycin exhibited good activity, and only 2 isolates were nonsusceptible to this antibiotic. Resistance to linezolid was observed in 2 MRSA isolates and in 16 CoNS. The cfr gene was detected in 7 of these 18 isolates. Vancomycin and teicoplanin tolerance was 9.6% and 21.9%, respectively, in MRSA isolates. We detected the hGISA phenotype in 5.8% of MRSA isolates. Vancomycin MICs by the Etest were slightly higher than those obtained by broth microdilution. Daptomycin retained activity against isolates that were not susceptible to linezolid, teicoplanin, or quinupristin-dalfopristin.