penicillin g was more active than ampicillin and piperacillin against group b streptococci ( mic90 0.1 , 0.12 and 0.24 mg/l respectively ) and ampicillin was the most active against list . monocytogenes ( mic90 0.6 mg/l ) .
C0031955
piperacillin
C0002680
ampicillin