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J Antimicrob Chemother. 2014 Jul;69(7):1825-9. doi: 10.1093/jac/dku040. Epub 2014 Mar 21.

Serratia marcescens harbouring SME-type class A carbapenemases in Canada and the presence of blaSME on a novel genomic island, SmarGI1-1.

Author information

1
National Microbiology Laboratory, Winnipeg, MB, Canada.
2
London Health Sciences Centre, London, ON, Canada.
3
British Columbia Public Health Microbiology and Reference Laboratory, Vancouver, BC, Canada.
4
Laboratoire de santé publique du Québec, Sainte-Anne-de-Bellevue, QC, Canada.
5
Moncton Hospital, Moncton, NB, Canada.
6
Cadham Provincial Laboratory, Winnipeg, MB, Canada.
7
Mount Sinai Hospital, Toronto, ON, Canada.
8
National Microbiology Laboratory, Winnipeg, MB, Canada michael.mulvey@phac-aspc.gc.ca.

Abstract

OBJECTIVES:

An increasing prevalence since 2010 of Serratia marcescens harbouring the Ambler class A carbapenemase SME prompted us to further characterize these isolates.

METHODS:

Isolates harbouring bla(SME) were identified by PCR and sequencing. Phenotypic analysis for carbapenemase activity was carried out by a modified Hodge test and a modified Carba NP test. Antimicrobial susceptibilities were determined by Etest and Vitek 2. Typing was by PFGE of macrorestriction digests. Whole-genome sequencing of three isolates was carried out to characterize the genomic region harbouring the bla(SME)-type genes.

RESULTS:

All S. marcescens harbouring SME-type enzymes could be detected using a modified Carba NP test. Isolates harbouring bla(SME) were resistant to penicillins and carbapenems, but remained susceptible to third-generation cephalosporins, as well as fluoroquinolones and trimethoprim/sulfamethoxazole. Isolates exhibited diverse genetic backgrounds, though 57% of isolates were found in three clusters. Analysis of whole-genome sequence data from three isolates revealed that the bla(SME) gene occurred in a novel cryptic prophage genomic island, SmarGI1-1.

CONCLUSIONS:

There has been an increasing occurrence of S. marcescens harbouring bla(SME) in Canada since 2010. The bla(SME) gene was found on a genomic island, SmarGI1-1, that can be excised and circularized, which probably contributes to its dissemination amongst S. marcescens.

KEYWORDS:

carbapenem resistance; infection control; mobilization

PMID:
24659751
DOI:
10.1093/jac/dku040
[Indexed for MEDLINE]

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