Aspects of the mechanism of action of some cephalosporins.

Cephaloridine and cephalexin had no effect on ribonucleic acid (RNA), deoxyribonucleic acid (DNA), or protein synthesis in Escherichia coli. However, cephalosporin 7/30 [7-(S-benzylthioacetamido)-cephem-3-ylmethyl-N -dimethyldithiocarbamate-4-carboxylic acid] and dimethyldithiocarbamate (DMDT), which occupies the side chain at position 3 in the 7/30 molecule, inhibited protein synthesis (and, to a lesser extent, RNA and DNA syntheses) in E. coli and had an inhibitory effect on the growth of Saccharomyces carlsbergensis. A bioautograph technique showed that two inhibitory spots were obtained with 7/30 but only one such spot with cephaloridine. Release of DMDT onto or in the bacterial cell may be responsible for "unusual" mode of action of cephalosporin 7/30.