title: Cephamycins, a new family of beta-lactam antibiotics: antibacterial activity and resistance to beta-lactamase degradation.
abstract: The susceptibility to some cephalosporin antibiotics and to cephamycin C, a member of a new family of beta-lactam antibiotics, was evaluated for 466 cultures representing 11 different genera or species of gram-negative clinical isolates. The susceptibility of 39 gram-negative cultures known to produce beta-lactamase was also determined. The beta-lactamase activity of a representative group of the clinical isolates and the 39 enzyme producers was studied with the cephalosporins (cephalothin and cephaloridine) and cephamycin C as substrates and was related to the in vitro disc susceptibility to these same antibiotics. The significant resistance to beta-lactamase displayed by the cephamycins is reflected in the kinetics of enzyme activity (K(m) and V(max)) that are reported for the cephalosporins and the cephamycins. Resistance to beta-lactamase is probably one of the reasons that many cephalosporin-resistant cultures are susceptible to cephamycin C.
mesh_terms: D001419:Bacteria / Q000187:drug effects*; D002511:Cephalosporins / Q000494:pharmacology*; D004754:Enterobacter / Q000201:enzymology; D004790:Enzyme Induction / Q000187:drug effects; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D010405:Penicillinase / Q000096:biosynthesis*; D011511:Proteus / Q000201:enzymology
chemical_list: D002511:Cephalosporins; D010405:Penicillinase