title: Phenotypic and enzymatic comparative analysis of the novel KPC variant KPC-5 and its evolutionary variants, KPC-2 and KPC-4.
abstract: A novel Klebsiella pneumoniae carbapenemase (KPC) variant, designated bla(KPC-5), was discovered in a carbapenem-resistant Pseudomonas aeruginosa clinical isolate from Puerto Rico. Characterization of the upstream region of bla(KPC-5) showed significant differences from the flanking regions of other bla(KPC) variants. Comparison of amino acid sequences with those of other KPC enzymes revealed that KPC-5 was an intermediate between KPC-2 and KPC-4, differing from KPC-2 by a single amino acid substitution (Pro(103)-->Arg), while KPC-4 contained Pro(103)-->Arg plus an additional amino acid change (Val(239)-->Gly). Transformation studies with an Escherichia coli recipient strain showed differences in the properties of the KPC variants. KPC-4 and KPC-5 both had pIs of 7.65, in contrast with the pI of 6.7 for KPC-2. KPC-2 transformants were less susceptible to the carbapenems than KPC-4 and KPC-5 transformants. These data correlated with higher rates of imipenem hydrolysis for KPC-2 than for KPC-4 and KPC-5. However, KPC-4 and KPC-5 transformants had higher ceftazidime MICs, and the enzymes from these transformants had slightly better hydrolysis of this drug than KPC-2. KPC-4 and KPC-5 were more sensitive than KPC-2 to inhibition by clavulanic acid in both susceptibility testing and hydrolysis assays. Thus, KPC enzymes may be evolving through stepwise mutations to alter their spectra of activity.
authors.affiliation: Center for Research in Anti-Infectives and Biotechnology, Omaha, NE 68178, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wolter
authors.forename: Philip M
authors.initials: PM
authors.lastname: Kurpiel
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
authors.forename: Marie-France I
authors.initials: MF
authors.lastname: Palepou
authors.forename: Richard V
authors.initials: RV
authors.lastname: Goering
authors.forename: Nancy D
authors.initials: ND
authors.lastname: Hanson
mesh_terms: D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016470:Bacteremia / Q000382:microbiology; D019818:Clavulanic Acid / Q000494:pharmacology; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D014644:Genetic Variation; D006868:Hydrolysis; D007525:Isoelectric Focusing; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D020033:Protein Isoforms; D020133:Reverse Transcriptase Polymerase Chain Reaction; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D020033:Protein Isoforms; D065093:beta-Lactamase Inhibitors; D019818:Clavulanic Acid; C491478:beta-lactamase KPC-2; D001618:beta-Lactamases