using escherichia coli a study of the piod values allowed us to separate the beta-lactam antibiotics studied into two groups : those whose piod were concentration-dependent ( ampicillin , carbenicillin , ticarcillin , moxalactam , ceftazidime , cefsulodin , cefotaxime ) and those whose piod were concentration-independent ( or weakly dependent ) ( azlocillin , mezlocillin , piperacillin ) .
C0002680
ampicillin
C0031955
piperacillin