In vitro susceptibility to daptomycin and linezolid should be obtained for strains that are resistant to -lactams, vancomycin, or aminoglycosides (Class I; Level of Evidence C). Table 11. Therapy for Endocarditis Involving a Prosthetic Valve or Other Prosthetic Material 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 6 equally divided doses 6 Class I; Level of Evidence B Vancomycin should be used in patients with immediate-type hypersensitivity reactions to -lactam antibiotics (see Table 5 for dosing guidelines); cefazolin may be substituted for nafcillin or oxacillin in patients with non immediate-type hypersensitivity reactions to penicillins. Plus Rifampin 900 mg per 24 h IV or orally in 3 equally divided doses Plus Gentamicin 3 mg/kg per 24 h IV or IM in 2 or 3 equally divided doses Oxacillin-resistant strains Vancomycin 30 mg/kg 24 h in 2 equally divided doses 6 Class I; Level of Evidence B Adjust vancomycin to a trough concentration of 10 20 g/mL. (see text for gentamicin alternatives) Plus Rifampin 900 mg/24 h IV/PO in 3 equally divided doses Plus Gentamicin 3 mg/kg per 24 h IV/IM in 2 or 3 equally divided doses IM indicates intramuscular; and IV, intravenous. *Doses recommended are for patients with normal renal function. Gentamicin should be administered in close proximity to vancomycin, nafcillin, or oxacillin dosing. See Table 7 for appropriate dose of gentamicin. Role of Aminoglycosides in the Treatment of Patients With Enterococcal IE: Special Considerations Aminoglycoside-containing regimens have been a cornerstone of antimicrobial therapy for enterococcal IE187 and have been recommended as standard therapy in previous (1995) AHA Since the publication of the latest (2005) AHA statement on antimicrobial therapy of patients with IE,12 the frequency of aminoglycoside-resistant strains of enterococci has increased significantly. 