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J Antimicrob Chemother. 2007 Aug;60(2):258-62. Epub 2007 May 31.

Characterization of the IncA/C plasmid pCC416 encoding VIM-4 and CMY-4 beta-lactamases.

Author information

1
Dipartimento di Biologia Molecolare, Laboratorio di Fisiologia e Biotecnologia dei Microorganismi, Università di Siena, Siena, and Laboratorio di Microbiologia, Ospedale di Circolo, Varese, Italy.

Abstract

OBJECTIVES:

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.

PMID:
17540674
DOI:
10.1093/jac/dkm171
[Indexed for MEDLINE]

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