title: Correlation of beta-lactamase stability and antibacterial activity of beta-lactams in beta-lactamase-producing bacteria and respective transconjugants.
abstract: A total of 343 Gram-negative bacteria were isolated and identified from urine specimens of patients with urinary tract infections. All the bacteria were investigated for their production of beta-lactamases by the nitrocefin test. beta-lactamase-producing strains were tested by the Datta method to detect any transfer of beta-lactamase production to a receiving E. coli K12 RN-strain. MICs of six beta-lactamase-stable compounds (ceftazidime, ceftriaxone, cefamandole, cefoxitin, cefotaxime, cefuroxime) were determined against all the beta-lactamase transferring bacteria and their respective transconjugants by a miniaturized dilution broth method. beta-lactamases produced by donors and transconjugants were purified and identified by determination of the isoelectric point by focusing; their hydrolytic activity was assessed by a spectrophotometric method using cytochrome c reduction. A total of 129 bacteria out of 343 produced beta-lactamases and 27 of these transferred the beta-lactamase production by conjugation. The beta-lactamases isolated from donors and transconjugants had the same pl and the same substrate profile. Ceftazidime was more stable to all the beta-lactamases isolated and more active against all the bacteria examined than the other compounds.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002435:Cefamandole / Q000494:pharmacology; D002439:Cefotaxime / Q000494:pharmacology; D002440:Cefoxitin / Q000494:pharmacology; D002442:Ceftazidime / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D002444:Cefuroxime / Q000494:pharmacology; D003227:Conjugation, Genetic; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D008826:Microbial Sensitivity Tests; D011815:R Factors / Q000187:drug effects; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D002435:Cefamandole; D002440:Cefoxitin; D002443:Ceftriaxone; D002442:Ceftazidime; D001618:beta-Lactamases; D002439:Cefotaxime; D002444:Cefuroxime