A defectiva and Granulicatella species (G elegans, G adiacens, G paraadiacens, and G balaenopterae), formerly known as nutritionally variant strep- tococci, are detected by automated blood culture systems but may yield pleomorphic forms by Gram stain and will not grow on subculture unless chocolate agar or other media supple- mented with pyridoxal or cysteine is used. Treatment regimens outlined for VGS, A. defectiva, and Granulicatella species are subdivided into categories based on penicillin MIC data. Native Valve Highly Penicillin-Susceptible VGS and S gallolyticus (bovis) (MIC 0.12 g/mL) Bacteriological cure rates 98% may be anticipated in patients who complete 4 weeks of therapy with parenteral penicillin or ceftriaxone for IE caused by highly penicillin-susceptible VGS or S gallolyticus (bovis)118,119 (Table 7). Ampicillin is a reasonable alternative to penicillin and has been used when penicillin is not available because of supply deficiencies. The addition of gentamicin sulfate to penicillin exerts a synergistic killing effect in vitro on VGS and S gallolyticus (bovis). The combination of penicillin or ceftriaxone with gentamicin results in synergistic killing in animal models of VGS or S gallolyticus (bovis) experimental IE. 