Ampicillin sodium 2 g IV every 4 h 4 6 4 6 Class IIa; Level of Evidence B Or Aqueous penicillin G sodium 18 30 million U/24 h IV either continuously or in 6 equally divided doses Plus Gentamicin sulfate 3 mg/kg ideal body weight in 2 3 equally divided doses Or Double -lactam Ampicillin 2 g IV every 4 h 6 Class IIa; Level of Evidence B Recommended for patients with initial creatinine clearance <50 mL/min or who develop creatinine clearance <50 mL/min during therapy with gentamicin-containing regimen. Plus Ceftriaxone 2 g IV every 12 h 6 IV indicates intravenous. *For patients unable to tolerate a -lactam, see Table 14. Doses recommended are for patients with normal renal and hepatic function. Dose of gentamicin should be adjusted to achieve a peak serum concentration of 3 to 4 g/mL and a trough concentration of <1 g/mL. Baddour et al Infective Endocarditis in Adults 1457 The decision of whether to use an ami- noglycoside-containing regimen must be individualized for each patient. The rationale and recommendations for spe- cific aminoglycoside-containing regimens for the treatment of enterococcal IE based on in vitro susceptibilities are dis- cussed in the following groups of patients and in Tables 12 through 15. Recommendations 1. Gentamicin should be administered in daily mul- tiple divided doses (total, 3 mg kg 1 ) rather than a single daily dose to patients with enterococ- cal IE and normal renal function (Class I; Level of Evidence B). with the dose adjusted to achieve a 1-hour serum con- centration of 3 g/mL and a trough concentration of <1 g/mL (Class IIa; Level of Evidence B). Enterococcal Endocarditis Susceptible to Penicillin, Vancomycin, and Aminoglycosides Antimicrobial regimens outlined in Table 12 are reasonable for treatment of patients with IE caused by these organisms. 