title: Characterization of the IncA/C plasmid pCC416 encoding VIM-4 and CMY-4 beta-lactamases.
abstract: OBJECTIVE
  To characterize the antibiotic resistance regions of pCC416, a VIM-4- and CMY-4-encoding plasmid from clinical enterobacteria, and to elucidate its relation with the CMY-encoding plasmids widely diffused in Salmonella.
  
  
  METHODS
  The enterobacterial multiresistant plasmid pCC416 was derived from an Escherichia coli transconjugant and characterized. Conventional and long-range PCR assays were performed using primers specific for VIM-4- and CMY-4-encoding segments of pCC416. Amplicons were characterized by sequencing. blaVIM-4, blaCMY-4 and IntI1-specific probes were prepared from PCR products and used for the identification of various pCC416 clones. VIM- and CMY-positive BamHI and Sau3AI fragments of pCC416 were cloned into pACYC184 and their sequences were determined by gene walking.
  
  
  RESULTS
  The pCC416 plasmid contained two distinct resistant loci carrying beta-lactamase genes. The blaVIM-4 gene was part of an integron located in a complex, multidrug-resistant region of novel structure, interspersed with mobile elements or remnants thereof and being similar to various regions of other resistance plasmids. Nevertheless, a region in the 3' end of this structure resembled the respective region found in a CMY-2-encoding plasmid from Salmonella. The blaCMY-4 gene was identified within an 11.3 kb region also related to the CMY-2-encoding plasmids.
  
  
  CONCLUSIONS
  pCC416 probably evolved from an IncA/C2, CMY-encoding plasmid through acquisition of a VIM-encoding In4-type integron providing an example of accretion of resistance determinants in a single replicon.
authors.affiliation: Dipartimento di Biologia Molecolare, Laboratorio di Fisiologia e Biotecnologia dei Microorganismi, Università di Siena, Siena, and Laboratorio di Microbiologia, Ospedale di Circolo, Varese, Italy.
authors.forename: Céline
authors.initials: C
authors.lastname: Colinon
authors.forename: Vivi
authors.initials: V
authors.lastname: Miriagou
authors.forename: Alessandra
authors.initials: A
authors.lastname: Carattoli
authors.forename: Francesco
authors.initials: F
authors.lastname: Luzzaro
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Rossolini
mesh_terms: D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004755:Enterobacteriaceae / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D001618:beta-Lactamases; C476341:beta-lactamase CMY-4, Salmonella enterica; C477893:beta-lactamase bla(VIM-4), Pseudomonas aeruginosa