Many experts regularly use cefazolin for S aureus IE instead of nafcillin because of drug Table 10. Therapy for NVE Caused by Staphylococci Regimen Dose* and Route Duration, wk Strength of Recommendation Comments Oxacillin-susceptible strains Nafcillin or oxacillin 12 g/24 h IV in 4 6 equally divided doses 6 Class I; Level of Evidence C For complicated right-sided IE and for left-sided IE; for uncomplicated right-sided IE, 2 wk (see text). For penicillin-allergic (nonanaphylactoid type) patients Consider skin testing for oxacillin-susceptible staphylococci and questionable history of immediate- type hypersensitivity to penicillin. Cefazolin* 6 g/24 h IV in 3 equally divided doses 6 Class I; Level of Evidence B Cephalosporins should be avoided in patients with anaphylactoid-type hypersensitivity to -lactams; vancomycin should be used in these cases. Oxacillin-resistant strains Vancomycin 30 mg/kg per 24 h IV in 2 equally divided doses 6 Class I; Level of Evidence C Adjust vancomycin dose to achieve trough concentration of 10 20 g/mL (see text for vancomycin alternatives). Daptomycin 8 mg/kg/dose 6 Class IIb; Level of Evidence B Await additional study data to define optimal dosing. IE indicates infective endocarditis; IV, intravenous; and NVE, native valve infective endocarditis. *Doses recommended are for patients with normal renal function. For specific dosing adjustment and issues concerning vancomycin, see Table 7 footnotes. Baddour et al Infective Endocarditis in Adults 1453 tolerability and cost, for MSSA IE in penicillin-intolerant patients, or to facilitate outpatient antibiotic administration. Vancomycin is often recommended as an alternative to -lactam therapy for MSSA IE. 