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J Antimicrob Chemother. 2011 Feb;66(2):287-90. doi: 10.1093/jac/dkq423. Epub 2010 Nov 26.

Characterization of multidrug-resistant Enterobacteriaceae carrying plasmid-mediated quinolone resistance mechanisms in Spain.

Author information

1
Instituto de Salud Carlos III, Centro Nacional de Microbiología, Majadahonda, Madrid, Spain.

Abstract

OBJECTIVES:

The aim of this study was to detect and characterize plasmid-mediated quinolone resistance determinants as well as genes responsible for additional resistances in Enterobacteriaceae isolates in Spain.

METHODS:

The resistance genes were identified by PCR and sequencing. Plasmid analysis was carried out by S1-PFGE and PCR-based replicon typing. Conjugation assays were performed to link resistance genes to plasmids. The genetic relationships among the strains were determined by XbaI-PFGE.

RESULTS:

One hundred and twenty-three isolates carried qnr as the only quinolone resistance determinant. One Salmonella Bredeney was positive for qnrB2 harboured on a 320 kb conjugative IncHI2 plasmid. One Salmonella Newport was positive for qnrB4 harboured on a 70 kb conjugative IncFIIs plasmid. Twenty-five Salmonella Thompson were positive for qnrA1. Twenty-two harboured a 220 kb non-conjugative and non-typeable plasmid, two a 220 kb conjugative IncHI2 plasmid and one a 120 kb non-conjugative IncA/C plasmid. qnrS1 was always detected on non-conjugative ColE(TP) plasmids of various sizes. Thus, two Salmonella Montevideo strains carried a 20 kb plasmid while Salmonella Typhimurium strains carried plasmids of 10 kb (n = 91) or 30 kb (n = 2). One Escherichia coli was positive for qnrA1 detected on a 220 kb conjugative IncHI2 plasmid. qnr alleles and β-lactamases were associated in Salmonella Bredeney (harbouring bla(SHV-12)), Salmonella Newport (harbouring bla(DHA-1)) and E. coli (harbouring bla(CTX-M-9)).

CONCLUSIONS:

This is the first epidemiological study of qnr genes in Enterobacteriaceae isolates from Spain. Salmonella plasmids bearing qnr alleles are not a localized phenomenon in Spain and wide variation in plasmids and co-resistance was detected. The presence of qnr determinants in Salmonella serotypes commonly reported in human disease is concerning.

PMID:
21115442
DOI:
10.1093/jac/dkq423
[Indexed for MEDLINE]

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