bay k 4999 and piperacillin , two new substituted ampicillins , were compared with other beta-lactam antibiotics , including carbenicillin , azlocillin , mezlocillin , benzylpenicillin , ampicillin , and cefoxitin , against a wide range of gram-positive and -negative organisms .
C0031955
piperacillin
C0002680
ampicillin