In patients with normal renal function, it is reasonable to administer gentamicin every 8 hours with the dose adjusted to achieve a 1-hour serum con- centration of 3 g/mL and a trough concentration of <1 g/ mL. Increasing the dose of gentamicin in these patients did not result in enhanced efficacy but did increase the risk of Many patients with enterococcal IE are managed in a nontertiary care facility, and the laboratory may not have the capability for rapid determination of serum gentamicin concentrations or may not have a clinical pharmacist avail- able to assist in optimal dosing adjustments. These and other factors have prompted studies to evaluate the efficacy of non gentamicin-containing regimens for the treatment of Table 12. Therapy for Endocarditis Involving a Native or Prosthetic Valve or Other Prosthetic Material Resulting From Enterococcus Species Caused by Strains Susceptible to Penicillin and Gentamicin in Patients Who Can Tolerate -Lactam Therapy* Regimen Dose and Route Duration, wk Strength of Recommendation Comments Either Class IIa; Level of Evidence B Native valve: 4-wk therapy recommended for patients with symptoms of illness <3 mo; 6-wk therapy recommended for native valve symptoms >3 mo and for patients with prosthetic valve or prosthetic material. Recommended for patients with creatinine clearance >50 mL/min. 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. 