Vancomycin is often recommended as an alternative to -lactam therapy for MSSA IE. As outlined above, -lactam allergy evaluation should be conducted in every case in which vancomycin is considered for use because poorer outcomes related to vancomycin therapy for a variety of MSSA infec- tions are well recognized.140 Clindamycin has been associated with IE relapse and is For MSSA IE in patients with anaphy- lactoid-type -lactam allergy who exhibit either a suboptimal response to vancomycin or vancomycin allergy, -lactam desensitization should be considered as noted above.159 Daptomycin is a reasonable alternative to vancomycin for adults in the treatment of S aureus NVE. In the above-noted of S aureus bacteremia and right-sided IE, this agent (at 6 mg kg 1 ) was noninferior to standard ther- apy with vancomycin or an antistaphylococcal penicillin plus low-dose, short-course gentamicin. Importantly, the small number (n=18; 9 in each arm) of patients with left-sided IE enrolled in the trial prevented meaningful conclusions on the comparative efficacy of daptomycin in this infection. For this reason, the FDA indication for daptomycin explicitly omitted left-sided IE. However, in an observational study, high-dose daptomycin ( 9 mg/kg per dose) for treatment of left-sided IE was as effective as standard-of-care therapy and cleared MRSA bacteremia significantly faster than did standard-of- The emergence of organisms with decreased susceptibility to daptomycin was observed in 5% of daptomycin-treated patients. All of these patients needed but for a variety of rea- sons did not receive surgical intervention for debridement of deep-seated infections or left-sided IE. As indicated, the FDA-approved dose of daptomycin for S aureus bacteremia and right-sided IE is currently 6 mg/kg IV once daily. 