PVE, NVE with symptoms >3 mo, or treatment with a double -lactam regimen require a minimum of 6 wk of therapy. Plus Ceftriaxone 2 g IV every 12 h Alternative for streptomycin susceptible/gentamicin resistant Either 4 6 Class IIa; Level of Evidence B Use is reasonable only for patients with availability of rapid streptomycin serum concentrations. Patients with creatinine clearance <50 mL/min or who develop creatinine clearance <50 mL/min during treatment should be treated with double - lactam regimen. Patients with abnormal cranial nerve VIII function should be treated with double -lactam regimen. Ampicillin sodium 2 g IV every 4 h Or Aqueous penicillin G sodium 18 30 million U/24 h IV either continuously or in 6 equally divided doses Plus Streptomycin sulfate 15 mg/kg ideal body weight per 24h IV or IM in 2 equally divided doses IM indicates intramuscular; IV, intravenous; NVE, native valve infective endocarditis; and PVE, prosthetic valve infective endocarditis. *For patients unable to tolerate a -lactam, see Table 14. Doses recommended for patients with normal renal and hepatic function. Streptomycin dose should be adjusted to obtain a serum peak concentration of 20 to 35 g/mL and a trough concentration of <10 g/mL. synthesis and is approved for use by the FDA in adults and children. It is not approved by the FDA for treatment of IE. Linezolid is bacteriostatic in vitro against enterococci, and susceptibility of enterococci to linezolid ranges from 97% to 99%, including strains that are multidrug resistant. Enterococci with MIC >2 g/mL are considered to be resistant to linezolid. However, linezolid-resistant strains have devel- oped during treatment.201 In a small number of patients, linezolid was effective ther- apy of vancomycin-resistant E faecium IE.174 Birmingham et reported cure in 17 of 22 courses of therapy (77%) for E faecium IE. 