title: Evolution of plasmid-coded resistance to broad-spectrum cephalosporins.
abstract: A clinical isolate of Klebsiella ozaenae with transferable resistance to broad-spectrum cephalosporins produces a beta-lactamase determined by plasmid pBP60. The beta-lactamase had the same isoelectric point as SHV-1 (7.6). From heteroduplex analysis, an extensive homology between the two bla genes could be deduced; therefore, the new beta-lactamase was designated SHV-2. Enzymatic studies revealed that SHV-2 was able to hydrolyze broad-spectrum cephalosporins due to an increased affinity of these compounds for the enzyme. The assumption that SHV-2 is a natural mutant of SHV-1 was strongly supported by the isolation of a laboratory mutant of SHV-1 that showed activities similar to those of SHV-2.
mesh_terms: D002511:Cephalosporins / Q000378:metabolism / Q000494:pharmacology*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D004352:Drug Resistance, Microbial; D005796:Genes; D005798:Genes, Bacterial; D007709:Klebsiella / Q000187:drug effects / Q000235:genetics*; D009154:Mutation; D010957:Plasmids; D012689:Sequence Homology, Nucleic Acid; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
chemical_list: D002511:Cephalosporins; D004269:DNA, Bacterial; D001618:beta-Lactamases