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J Antimicrob Chemother. 2009 Dec;64(6):1156-64. doi: 10.1093/jac/dkp350. Epub 2009 Sep 25.

Diversity of antimicrobial resistance pheno- and genotypes of methicillin-resistant Staphylococcus aureus ST398 from diseased swine.

Author information

1
Institute of Farm Animal Genetics, Friedrich-Loeffler-Institute (FLI), Neustadt-Mariensee, Germany.

Abstract

OBJECTIVES:

Fifty-four methicillin-resistant Staphylococcus aureus (MRSA) ST398 isolates from unrelated diseased swine collected all over Germany were comparatively investigated for their antimicrobial resistance and virulence properties, and for their genomic relatedness.

METHODS:

MICs of 30 antimicrobial agents were determined by broth microdilution. Resistance and virulence genes were detected via a diagnostic DNA microarray and specific PCRs. The genomic relationships were determined by ApaI-PFGE, spa typing and SCCmec typing.

RESULTS:

Twenty-two distinct resistance patterns were observed. All 54 isolates were tetracycline resistant, mediated by tet(M), tet(K) and/or tet(L), with 14 isolates being only resistant to beta-lactam antibiotics and tetracyclines. Trimethoprim resistance, seen in 28 isolates, was mostly due to the gene dfrK or dfrG. Among the 24 macrolide/lincosamide-resistant isolates, the genes erm(A), erm(B) and/or erm(C) were detected. The two chloramphenicol/florfenicol-resistant isolates harboured the gene fexA. The eight gentamicin-resistant isolates carried the gene aacA/aphD. Fifty-three isolates harboured SCCmec type V elements while the remaining one carried mecA and ugpQ, but no recombinase genes. All isolates were PVL negative, but one and three isolates, respectively, were positive for the enterotoxin B and enterotoxin K and Q genes. Eight different spa types were identified with t011 being the most predominant. Six ApaI-PFGE clusters with up to nine individual patterns were detected.

CONCLUSIONS:

MRSA ST398 isolates varied slightly in their virulence properties and spa types but differed distinctly in their antimicrobial resistance pheno- and genotypes as well as their ApaI-PFGE patterns. These data underline the ability of ST398 to acquire genetic material that might increase antimicrobial resistance and virulence.

PMID:
19808235
DOI:
10.1093/jac/dkp350
[Indexed for MEDLINE]

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