title: Quantitative analysis of beta-lactamase production of multiple resistance to beta-lactam antibiotics in clinical isolates of Escherichia coli.
abstract: A simple test of procedure is described for the rapid evaluation of beta-lactamase substrate profiles against all the clinically important beta-lactam antibiotics. By use of this method 100 clinical isolates of Escherichia coli were classified into four beta-lactamase types: TEM-like, 35; chromosomal-like, 56; others, 3; beta-lactamase-less, 6 strains. They were tested for their susceptibilities to cefuroxime, cefoxitin, cefamandole, cephalexin, cefazolin, cephaloridine, cephalothin, ampicillin, carbenicillin and kanamycin. The isolates of each of TEM-like and chromosomal-like beta-lactamase types showed a good correlation between the beta-lactamase activity and the minimum inhibitory concentration (MIC) determined by the agar dilution method and the least square line analysis; MIC = ax + b, where x is enzyme activity, and a and b are constants. TEM-like beta-lactamase increased the resistance to ampicillin and carbenicillin markedly and that to cephalothin, cephaloridine and cefamandole moderately. In contrast, chromosomal-like beta-lactamase increased the resistance to ampicillin, cephalexin and cephalothin only slightly.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology; D004927:Escherichia coli Infections / Q000382:microbiology; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008826:Microbial Sensitivity Tests; D001618:beta-Lactamases / Q000096:biosynthesis*; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D001618:beta-Lactamases