Single-nucleotide polymorphism in the SCCmec-orfX junction distinguishes between livestock-associated MRSA CC398 and human epidemic MRSA strains

U Reischl; J Frick; S Hoermansdorfer; H Melzl; M Bollwein; H J Linde; K Becker; R Köck; C Tuschak; U Busch; A Sing

doi:10.2807/ese.14.49.19436-en

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Single-nucleotide polymorphism in the SCCmec-orfX junction distinguishes between livestock-associated MRSA CC398 and human epidemic MRSA strains
U Reischl¹ , J Frick^2,3 , S Hoermansdorfer² , H Melzl¹ , M Bollwein¹ , H J Linde¹ , K Becker⁴ , R Köck^4,5 , C Tuschak² , U Busch² , A Sing²
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Affiliations: ¹ Institute of Medical Microbiology and Hygiene, University Hospital of Regensburg, Regensburg, Germany ² Bavarian Health and Food Safety Authority, Oberschleißheim, Germany ³ Clinic for Swine, Veterinary Faculty, Ludwig-Maximilians-University, Oberschleissheim, Germany ⁴ Institute of Medical Microbiology, University Hospital Münster, Münster, Germany ⁵ Institute of Hygiene, University Hospital Münster, Münster, Germany

Correspondence:
U Reischl
udo.reischl klinik.uni-regensburg.de
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Citation style for this article: Reischl U, Frick J, Hoermansdorfer S, Melzl H, Bollwein M, Linde H J, Becker K, Köck R, Tuschak C, Busch U, Sing A. Single-nucleotide polymorphism in the SCCmec-orfX junction distinguishes between livestock-associated MRSA CC398 and human epidemic MRSA strains. Euro Surveill. 2009;14(49):pii=19436. https://doi.org/10.2807/ese.14.49.19436-en Received: 17 Aug 2009

Abstract

A number of real-time PCR assays for direct detection of methicillin-resistant Staphylococcus aureus (MRSA) in clinical specimens are targeting staphylococcal cassette chromosome mec (SCCmec) right extremity sequences and the S. aureus chromosomal orfX gene sequences located to the right of the SCCmec integration site. When testing 184 MRSA strains of human and animal origin from geographically distinct locations, we identified several characteristic single-nucleotide polymorphisms (SNPs) within the SCCmec-orfX junction of livestock-associated (LA) MRSA CC398 which serve as suitable strain markers for screening purposes. Within an assay time of 60 minutes and an additional 10 minutes for the melting curve analysis, all MRSA CC398 isolates were correctly identified by their characteristic Tm value in the commercial LightCycler MRSA Advanced test. Studies to confirm the diagnostic accuracy of the SNP-based strain identification assay with a larger collection of clinical and LA-MRSA strains are ongoing.