title: Cloning and characterization of blaVIM, a new integron-borne metallo-beta-lactamase gene from a Pseudomonas aeruginosa clinical isolate.
abstract: Production of a metallo-beta-lactamase activity was detected in a carbapenem-resistant Pseudomonas aeruginosa clinical isolate (isolate VR-143/97) from an Italian inpatient at the Verona University Hospital (northern Italy). The metallo-beta-lactamase determinant was isolated from a genomic library of VR-143/97, constructed in an Escherichia coli plasmid vector, by screening for clones with reduced susceptibility to imipenem. Sequencing of the cloned gene revealed that it encoded a new class B beta-lactamase that was named VIM-1. At the sequence level VIM-1 was rather divergent from the other class B enzymes (16.4 to 38.7% identity), overall being more similar to members of subclass B1 including the beta-lactamase II of Bacillus cereus (Bc-II), the Bacteroides fragilis CcrA, the Chryseobacterium meningosepticum BlaB, and the cassette-encoded IMP-1 enzymes. Among these, VIM-1 showed the highest degree of similarity to Bc-II. Similarly to blaIMP, blaVIM was also found to be carried on a gene cassette inserted into a class 1 integron. The blaVIM-containing integron was located on the chromosome of P. aeruginosa VR-143/97, and the metallo-beta-lactamase-encoding determinant was not transferable to E. coli by conjugation. Expression of the integron-borne blaVIM gene in E. coli resulted in a significant decrease in susceptibility to a broad array of beta-lactams (ampicillin, carbenicillin, piperacillin, mezlocillin, cefotaxime, cefoxitin, ceftazidime, cefoperazone, cefepime, and carbapenems), revealing a very broad substrate specificity of the VIM-1 enzyme.
authors.affiliation: Dipartimento di Biologia Molecolare, Sezione di Microbiologia, Università di Siena, 53100-Siena, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Lauretti
authors.forename: M L
authors.initials: ML
authors.lastname: Riccio
authors.forename: A
authors.initials: A
authors.lastname: Mazzariol
authors.forename: G
authors.initials: G
authors.lastname: Cornaglia
authors.forename: G
authors.initials: G
authors.lastname: Amicosante
authors.forename: R
authors.initials: R
authors.lastname: Fontana
authors.forename: G M
authors.initials: GM
authors.lastname: Rossolini
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000187:drug effects; D006801:Humans; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D001618:beta-Lactamases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D047090:beta-Lactams
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D047090:beta-Lactams; D001618:beta-Lactamases; C063912:carbapenemase