Commonly Susceptible Species Staphylococcus aureus * Staphylococcus haemolyticus Coagulase negative staphylococci Streptococcus agalactiae* Streptococcus dysgalactiae subsp equisimilis* Streptococcus pyogenes* Group G streptococci Clostridium perfringens Peptostreptococcus spp Inherently resistant organisms Gram negative organisms * denotes species against which it is considered that activity has been satisfactorily demonstrated in clinical studies.