Some experts have recommended daptomycin doses of 8 for the treatment of complicated methicillin- resistant S aureus (MRSA) bacteremia, particularly IE. This recommendation is based on the concentration-dependent properties of daptomycin, improved efficacy for infections caused by organisms with reduced susceptibility to dapto- mycin, and an attempt to reduce the emergence of resistance to daptomycin after vancomycin therapy.110 The evidence for these recommendations has come largely from in vitro PK/PD models using high-inoculum simulated endocardial vegeta- tions with S aureus111 and enterococci and from animal mod- els of IE.112 With regard to vancomycin, an AUC24 /MIC 400 is rec- ommended as the targeted PK/PD parameter for patients with serious S aureus infections.112 In an evaluation of 320 MRSA patients with complicated bacteremia, including IE, Kullar et al113 demonstrated that an AUC24 /MIC >421 was significantly associated with improved patient outcomes. /MIC ratio was associated with trough serum concentrations >15 mg/L, attainable if the vancomycin MIC was <1 mg/L. Antimicrobial Treatment Perspectives In many cases, the initial therapy of IE is empirical; typi- cally, results of blood cultures are monitored for hours to days until a pathogen is identified. During this time, empiri- cal antimicrobial therapy is administered with the expectation that the regimen will be revised once a pathogen is defined and susceptibility results are obtained. The selection of an optimal empiric regimen is usually broad and is based on fac- tors that relate to patient characteristics, prior antimicrobial exposures and microbiological findings, and epidemiological features. Therefore, infectious diseases consultation should occur at the time of empirical therapy initiation to help define because the selection of a regimen is highly variable. In this regard, please refer the Culture-Negative Endocarditis section of this statement and the related Table 6 for additional details. 