Ceftriaxone combined with gentamicin may be a reasonable alternative treatment option for VGS isolates with a penicillin MIC 0.5 g/mL that are susceptible to ceftriaxone (Class IIb; Level of Evidence C). Prosthetic Valve or Valvular Prosthetic Material Endocarditis of Prosthetic Valves or Other Prosthetic Material Caused by VGS and S gallolyticus (bovis) For patients with IE complicating prosthetic valves or other prosthetic material caused by a highly penicillin- susceptible strain (MIC 0.12 g/mL), it is reasonable to administer 6 weeks of therapy with penicillin or cef- triaxone with or without gentamicin for the first 2 weeks (Table 9). It is reasonable to administer 6 weeks of therapy with a combination of penicillin or ceftriaxone and gen- tamicin in patients with IE caused by a strain that is rela- tively or highly resistant to penicillin MIC >0.12 g/mL. Vancomycin is useful only for patients who are unable to tolerate penicillin, ceftriaxone, or gentamicin. Ampicillin is an acceptable alternative to penicillin if shortages of penicillin exist. Recommendations 1. Aqueous crystalline penicillin G or ceftriaxone for 6 weeks with or without gentamicin for the first 2 weeks is reasonable (Class IIa; Level of Evidence B). 2. It is reasonable to extend gentamicin to 6 weeks if the MIC is >0.12 g/mL for the infecting strain (Class IIa; Level of Evidence C). 3. Vancomycin can be useful in patients intolerant of penicillin, ceftriaxone, or gentamicin (Class IIa; Level of Evidence B). Streptococcus pneumoniae, Streptococcus pyogenes, and Groups B, C, F, and G -Hemolytic Streptococci IE caused by these streptococci is uncommon. There are few published reports of large case series evaluating management strategies for IE caused by these microorganisms. 