Penicillin relatively or fully resistant strain (MIC >0.12 g/mL) Aqueous crystalline penicillin sodium 24 million U/24 h IV either continuously or in 4 6 equally divided doses 6 Class IIa; Level of Evidence B Ampicillin 2 g IV every 4 h is a reasonable alternative to penicillin if a penicillin shortage exists. Or Ceftriaxone 2 g/24 h IV/IM in 1 dose 6 Class IIa; Level of Evidence B Plus Gentamicin sulfate 3 mg/kg per 24 h IV/IM in 1 dose 6 Vancomycin hydrochloride 30 mg/kg per 24 h IV in 2 equally divided doses 6 Class IIa; Level of Evidence B Vancomycin is reasonable only for patients unable to tolerate penicillin or ceftriaxone. IM indicates intramuscular; IV, intravenous; MIC indicates minimum inhibitory concentration; and VGS, viridans group streptococci. *Doses recommended are for patients with normal renal function. See Table 7 for appropriate dose of gentamicin. Although it is preferred that gentamicin (3 mg/kg) be given as a single daily dose to adult patients with endocarditis resulting from VGS, as a second option, gentamicin can be administered daily in 3 equally divided doses. See text and Table 7 for appropriate dose of vancomycin. cefotaxime (or ceftriaxone) are reasonable (Class IIa; Level of Evidence C). 4. The addition of vancomycin and rifampin to cefo- taxime (or ceftriaxone) may be considered in patients with IE caused by S pneumoniae that are resistant to cefotaxime (MIC >2 g/mL) (Class IIb; Level of Evidence C). 5. Because of the complexities of IE caused by S pneu- moniae, consultation with an infectious diseases spe- cialist is recommended (Class I; Level of Evidence C). 6. 