title: Characterization of BKC-1 class A carbapenemase from Klebsiella pneumoniae clinical isolates in Brazil.
abstract: Three Klebsiella pneumoniae clinical isolates demonstrating carbapenem resistance were recovered from different patients hospitalized at two medical centers in São Paulo, Brazil. Resistance to all β-lactams, quinolones, and some aminoglycosides was observed for these isolates that were susceptible to polymyxin B. Carbapenem hydrolysis, which was inhibited by clavulanic acid, was observed for all K. pneumoniae isolates that belonged to the same pulsed-field gel electrophoresis (PFGE) type and a novel sequence type (ST), ST1781 (clonal complex 442 [CC442]). A 10-kb nonconjugative incompatibility group Q (IncQ) plasmid, denominated p60136, was transferred to Escherichia coli strain TOP10 cells by electroporation. The full sequencing of p60136 showed that it was composed of a mobilization system, ISKpn23, the phosphotransferase aph3A-VI, and a 941-bp open reading frame (ORF) that codified a 313-amino acid protein. This ORF was named bla BKC-1. Brazilian Klebsiella carbapenemase-1 (BKC-1) showed a pI of 6.0 and possessed the highest identity (63%) with a β-lactamase of Sinorhizobium meliloti, an environmental bacterium. Hydrolysis studies demonstrated that purified BKC-1 not only hydrolyzed carbapenems but also penicillins, cephalosporins, and monobactams. However, the carbapenems were less efficiently hydrolyzed due to their very low kcat values (0.0016 to 0.031 s(-1)). In fact, oxacillin was the best substrate for BKC-1 (kcat /Km , 53,522.6 mM(-1) s(-1)). Here, we report a new class A carbapenemase, confirming the diversity and rapid evolution of β-lactamases in K. pneumoniae clinical isolates.
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil adrianagn@gmail.com.
authors.forename: Adriana Giannini
authors.initials: AG
authors.lastname: Nicoletti
authors.affiliation: Laboratório de Enzimologia, Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Marcelo F M
authors.initials: MF
authors.lastname: Marcondes
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Willames M B S
authors.initials: WM
authors.lastname: Martins
authors.affiliation: Laboratório Nacional de Computação Científica, Petrópolis, Brazil.
authors.forename: Luiz G P
authors.initials: LG
authors.lastname: Almeida
authors.affiliation: Laboratório Nacional de Computação Científica, Petrópolis, Brazil.
authors.forename: Marisa F
authors.initials: MF
authors.lastname: Nicolás
authors.affiliation: Laboratório Nacional de Computação Científica, Petrópolis, Brazil.
authors.forename: Ana T R
authors.initials: AT
authors.lastname: Vasconcelos
authors.affiliation: Laboratório de Enzimologia, Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Vitor
authors.initials: V
authors.lastname: Oliveira
authors.affiliation: Laboratório Alerta, Disciplina de Infectologia, Departamento de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Gales
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001426:Bacterial Proteins / Q000378:metabolism*; D001938:Brazil; D015780:Carbapenems / Q000378:metabolism / Q000494:pharmacology; D002511:Cephalosporins / Q000378:metabolism / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D008826:Microbial Sensitivity Tests; D008997:Monobactams / Q000378:metabolism / Q000494:pharmacology; D010406:Penicillins / Q000378:metabolism / Q000494:pharmacology; D016962:Sinorhizobium meliloti / Q000187:drug effects / Q000378:metabolism; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D015780:Carbapenems; D002511:Cephalosporins; D008997:Monobactams; D010406:Penicillins; D001618:beta-Lactamases; C063912:carbapenemase