title: In vitro activity and beta-lactamase stability of N-formimidoyl thienamycin compared to that of second and third generation cephalosporins.
abstract: N-Formimidoyl thienamycin (MK0787) was found to be active against 21 gram-negative isolates, selected for their beta-lactamase production. None of the crude beta-lactamases could hydrolyze MK0787 or cefoxitin, in contrast to cefotaxime which was moderately attacked by a number of enzymes. MK0787 behaved as a moderate inhibitor of most beta-lactamases, whereas cefoxitin and cefotaxime were strong inhibitors of cephalosporinases but not of broad-spectrum enzymes. The new compound had good penetration characteristics in a strain of Enterobacter cloacae, in contrast to cefoxitin. Against a number of trained cefamandole- and cefoxitin-resistant variants, MK0787 was clearly the most active of the compounds tested.
mesh_terms: D002511:Cephalosporins / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000201:enzymology; D015378:Imipenem; D011549:Pseudomonas / Q000187:drug effects; D013845:Thienamycins / Q000494:pharmacology*; D065093:beta-Lactamase Inhibitors
chemical_list: D002511:Cephalosporins; D013845:Thienamycins; D065093:beta-Lactamase Inhibitors; D015378:Imipenem