title: [Klebsiella oxytoca beta-lactamases: study of their action on 3d-generation cephalosporins].
abstract: Indole-positive Klebsiella pneumoniae or K. oxytoca are usually resistant to penicillins as a result of the production of a chromosomally-mediated beta-lactamase with a low level of synthesis (specific activity approximately 50 to 100 mU/mg). Although most strains are susceptible to the majority of cephalosporins, some strains exhibit resistance to cephalosporins including third-generation drugs. These resistant strains produce a chromosomally-mediated beta-lactamase with a high level of synthesis (specific activity approximately 5,000 mU/mg or higher). Four beta-lactamases have been identified on the basis of their isoelectric points: pI = 5.5, 5.7, 6.0 and 6.3; nevertheless they have similar kinetic constants, and are inhibited by clavulanic acid. These enzymes hydrolyze most third-generation cephalosporins, in the following order of decreasing velocities: cefoperazone, ceftriaxone, cefotaxime, cefodizime, cefpirome; ceftazidime, and cefoxitin, cefotetan, latamoxef, cephamycins which are totally resistant to these enzymes.
mesh_terms: D002511:Cephalosporins / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D002511:Cephalosporins; D001618:beta-Lactamases
vernacular_title: Bêtalactamases de Klebsiella oxytoca: étude de leur action sur les céphalosporines de troisième génération.