In vitro antibacterial activity and beta-lactamase stability of SCE-129, a new cephalosporin.

SCE-129 [3-4-carbamoyl-1-pyridiniomethyl-7beta- (d-alpha-sulfophenylacetamido)-ceph-3-em-4-carboxylate] is a cephalosporin that inhibits Pseudomonas aeruginosa and Staphylococcus aureus. SCE-129 is tenfold more active than carbenicillin in inhibiting P. aeruginosa. SCE-129 has poor activity against Enterobacteriaceae compared with other cephalosporins and is 16-fold less active than the cephalosporins against streptococci. The activity of SCE-129 does not correlate with beta-lactamase stability, although SCE-129 is resistant to hydrolysis by gram-positive and gram-negative bacteria. The compound does not inhibit the hydrolysis of other cephalosporins. Although SCE-129 acts synergistically with gentamicin to inhibit some Pseudomonas, this cannot be predicted based on knowledge of resistance to one or more compounds.