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. In a prospective study, the duration of antimicrobial therapy in native valve E faecalis IE was based on the duration of infec- tion before diagnosis and onset of effective therapy.196 Patients with <3 months duration of symptoms were treated success- fully with 4 weeks of antimicrobial therapy. Patients with 3 months duration of symptoms were successfully treated with 6 weeks of therapy. The duration of therapy for NVE is based on this work, and the regimens that may be considered are listed in Table 12. In patients with PVE, 6 weeks of antimicro- bial therapy is reasonable. Patients with preexisting mild (creatinine clearance, 30 50 mL/min) or severe (creatinine clearance, <30 mL/min) renal failure may not be able to safely complete a 4- to 6-week course of gentamicin therapy because of gentamicin-associated nephrotoxicity. Alternative regimens that should be considered include the use of streptomycin instead of gentamicin, short- course gentamicin therapy (2 3 weeks), and use of a non ami- noglycoside-containing double -lactam regimen. The risks and benefits of the alternative regimens are as follows. Streptomycin Therapy Although there are no published studies comparing the effi- cacy of regimens containing streptomycin or gentamicin, a similar cure rate was reported in a single noncomparative The main advantage is that streptomycin is less neph- rotoxic than gentamicin. There are several disadvantages of using streptomycin-containing regimens, including a lack of familiarity among clinicians with streptomycin, a higher risk of ototoxicity, which may not be reversible, and drug avail- ability limitations. In addition, most laboratories do not rou- tinely perform serum streptomycin assays and may not have access to a clinical pharmacist to assist in dosing adjustments. 