title: Phenotypic and enzymatic comparative analysis of the KPC variants, KPC-2 and its recently discovered variant KPC-15.
abstract: Sixteen different variants (KPC-2 to KPC-17) in the KPC family have been reported, and most current studies are focusing on KPC-2 and KPC-3. The KPC-15 variant, which isolated from Klebsiella pneumoniae in a Chinese hospital, was a recently discovered KPC enzyme. To compare the characteristics of KPC-15 and KPC-2, the variants were determined by susceptibility testing, PCR amplification and sequencing, and study of kinetic parameters. The strain harboring the KPC-15 showed resistance to 18 conventional antimicrobial agents, especially to cabapenem antibiotics, and the strain involving the KPC-2 also indicated resistance to cabapenem antibiotics, but both strains were susceptible to polymyxin B and colistin. The conjugation experiments showed that the changes of MIC values to the antibiotics were due to the transferred plasmids. The differences of amino acids were characterised at sites of 119 leucine and 146 lysine with KPC-15 and KPC-2. The minimum evolution tree indicated the KPC alleles evolution, and showed that the KPC-15 appeared to be homogenous with KPC-4 closely. Steady-state kinetic parameters showed the catalytic efficiency of KPC-15 was higher than that of KPC-2 for all tested antibiotics in this study. The catalytic efficiency of KPC-15 caused resistance to β-lactam antibiotics was higher than that of KPC-2. Meanwhile, an evolutionary transformation changed KPC from an efficient carbapenemase to its variants (KPC-15) with better ceftazidimase catalytic efficiency, and the old antibiotics polymyxin B and colistin might play a role in the therapy for multi-resistant strains.
authors.affiliation: Department of Clinical Lab Medicine, Taizhou Municipal Hospital affiliated with Taizhou University and the Institute of Molecular Diagnostics of Taizhou University, Zhejiang, China.
authors.forename: Dongguo
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Lab Medicine, Medical School and the Institute of Molecular Diagnostics of Taizhou University, Zhejiang, China.
authors.forename: Jiayu
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Thyroid Breast Surgery, Taizhou Municipal Hospital affiliated with Taizhou University, Zhejiang, China.
authors.forename: Linjun
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Hepatobiliary Surgery, Taizhou Municipal Hospital affiliated with Taizhou University, Zhejiang, China.
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Mou
authors.affiliation: Department of Quality Control, Taizhou Municipal Hospital affiliated with Taizhou University, Zhejiang, China.
authors.forename: Yijun
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins; D001483:Base Sequence; D019143:Evolution, Molecular; D014644:Genetic Variation; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010641:Phenotype; D001618:beta-Lactamases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001618:beta-Lactamases; C547585:beta-lactamase KPC-2, Klebsiella pneumoniae; C063912:carbapenemase