Journal Article

Genetic characterization of a novel metallo-β-lactamase gene, <i>bla</i><sub>IMP-13</sub>, harboured by a novel Tn<i>5051</i>-type transposon disseminating carbapenemase genes in Europe: report from the SENTRY worldwide antimicrobial surveillance programme

Mark A. Toleman, Doug Biedenbach, David Bennett, Ronald N. Jones and Timothy R. Walsh

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 52, issue 4, pages 583-590
Published in print October 2003 | ISSN: 0305-7453
Published online October 2003 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dkg410
Genetic characterization of a novel metallo-β-lactamase gene, blaIMP-13, harboured by a novel Tn5051-type transposon disseminating carbapenemase genes in Europe: report from the SENTRY worldwide antimicrobial surveillance programme

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Objective: In 2001, as part of the SENTRY worldwide antimicrobial surveillance programme, Pseudomonas aeruginosa 86–14571A was isolated at a hospital in Rome from a cancer patient with a bloodstream infection. The isolate was resistant to all antibiotics except amikacin, and displayed an imipenem MIC of 64 mg/L that decreased to 8 mg/L in the presence of EDTA. The resistance determinant was investigated.

Methods: The resistant determinant was cloned in Escherichia coli using a shotgun cloning approach.

Results: Sequence analysis revealed the presence of a novel IMP-type metallo-β-lactamase (MBL) gene, blaIMP-13. This encoded a protein displaying most identity to IMP variants: 93% and 92.3% identity, respectively, to IMP-8 and IMP-2 (previously identified in Italy). The protein had 19 amino acid changes from IMP-2 and 17 amino acid changes from IMP-8. The blaIMP-13 gene was found as a gene cassette in the first position of a class 1 integron. A 25 bp inverted repeat sequence IRi was identified 174 bp upstream of the class I integrase, which suggests that the integron is found on a Tn402-like transposon, or defective transposon derivative. This element, in turn, is located in the transposition locus (tnp region) of a Tn21 subfamily transposon that showed most identity to Tn5051, a transposon recently identified from a strain of Pseudomonas putida isolated in New York. Interestingly, the insertion point of the Tn402-like transposon and the sequence of the Tn5051-like genes were identical to those of the genetic element harbouring blaVIM-2 recently identified in Poland.

Conclusions: The resistance determinant of P. aeruginosa 86–14571A is a novel IMP-type MBL carried on a composite transposon responsible for wide geographical dissemination of MBL genes in Europe.

Keywords: Keywords: metallo-β-lactamases, Pseudomonas aeruginosa, integron Tn21, Tn402

Journal Article.  4736 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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