Journal Article

Characterization of a <i>Salmonella enterica</i> serovar Agona strain harbouring a class 1 integron containing novel OXA-type β-lactamase (<i>bla</i><sub>OXA-53</sub>) and 6′-<i>N</i>-aminoglycoside acetyltransferase genes [<i>aac(6′)-I30</i>]

Michael R. Mulvey, David A. Boyd, Lorea Baker, Oksana Mykytczuk, E. M. F. Reis, M. D. Asensi, D. P. Rodrigues and Lai-King Ng

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 54, issue 2, pages 354-359
Published in print August 2004 | ISSN: 0305-7453
Published online August 2004 | e-ISSN: 1460-2091 | DOI: http://dx.doi.org/10.1093/jac/dkh347
Characterization of a Salmonella enterica serovar Agona strain harbouring a class 1 integron containing novel OXA-type β-lactamase (blaOXA-53) and 6′-N-aminoglycoside acetyltransferase genes [aac(6′)-I30]

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Objective: To characterize by molecular methods a multidrug-resistant Salmonella enterica serovar Agona (S. enterica Agona) isolated from a hospitalized patient in Rio de Janeiro, Brazil.

Methods: The S. enterica Agona strain was screened by PCR and DNA sequencing for TEM, SHV and CTX-M-type β-lactamase genes, tet(A), (B), (C) and (D) tetracycline resistance genes, chloramphenicol resistance genes and class 1 integrons. Plasmid characterization was carried out by PCR and Southern hybridization analysis. PCR and PFGE were used to characterize nine other S. enterica Agona strains collected from hospitals in Rio de Janeiro.

Results: The study strain was found to harbour a 105 kb plasmid, which contained catA1, blaTEM-1, a class 1 integron with two novel genes labelled blaOXA-53 and aac(6′)-I30, respectively, and an additional unidentified aminoglycoside resistance gene. A second 53 kb plasmid from the same strain contained tet(D) and blaSHV-5. OXA-53 was shown to provide reduced susceptibility to ceftazidime, and its activity was inhibited in the presence of clavulanic acid. PFGE analysis of the nine other S. enterica Agona strains revealed two clusters of related strains (78% similarity), and PCR analysis showed that all strains contained the novel integron.

Conclusion: An S. enterica Agona strain was found to harbour three plasmid-encoded β-lactamases, one (OXA-53) on a novel class 1 integron that also contains a new aminoglycoside resistance gene, aac(6′)-I30. The multidrug resistance plasmids appear to have disseminated to other city hospitals via other S. enterica Agona strains.

Keywords: extended-spectrum β-lactamases; plasmid-encoded resistance; hospital-acquired

Journal Article.  3200 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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