title: Rapid detection, differentiation and typing of methicillin-resistant Staphylococcus aureus harbouring either mecA or the new mecA homologue mecA(LGA251).
abstract: The recent finding of a new mecA homologue, mecA(LGA251) , with only 70% nucleotide homology to the conventional mecA gene has brought the routine testing for mecA as a confirmatory test for methicillin-resistant Staphylococcus aureus (MRSA) into question. A multiplex PCR was designed to differentiate mecA(LGA251) from the known mecA together with detection of lukF-PV and the spa gene fragments, enabling direct spa typing by sequencing of the PCR amplicons. The PCR analysis and subsequent spa typing were validated on a large collection (n=185) of contemporary MRSA and methicillin-sensitive S. aureus isolates, including 127 isolates carrying mecA(LGA251) . The mecA(LGA251) gene was situated in staphylococcal cassette chromosome mec type XI elements, and sequence variation within a 631-bp fragment of mecA(LGA251) in 79 isolates indicated a very conserved gene sequence. Following a successful validation, the multiplex PCR strategy was implemented in the routine testing of MRSA for national surveillance. Over a 2-month period, among 203 samples tested, 12 new MRSA cases caused by isolates carrying mecA(LGA251) were identified, emphasizing the clinical importance of testing for these new MRSA isolates.
authors.affiliation: Department of Microbiological Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Stegger
authors.forename: P S
authors.initials: PS
authors.lastname: Andersen
authors.forename: A
authors.initials: A
authors.lastname: Kearns
authors.forename: B
authors.initials: B
authors.lastname: Pichon
authors.forename: M A
authors.initials: MA
authors.lastname: Holmes
authors.forename: G
authors.initials: G
authors.lastname: Edwards
authors.forename: F
authors.initials: F
authors.lastname: Laurent
authors.forename: C
authors.initials: C
authors.lastname: Teale
authors.forename: R
authors.initials: R
authors.lastname: Skov
authors.forename: A R
authors.initials: AR
authors.lastname: Larsen
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002440:Cefoxitin / Q000494:pharmacology; D002876:Chromosomes, Bacterial / Q000235:genetics; D017124:Conserved Sequence; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D058885:Multilocus Sequence Typing / Q000379:methods* / Q000592:standards; D046915:Penicillin-Binding Proteins; D010641:Phenotype; D013203:Staphylococcal Infections / Q000235:genetics / Q000382:microbiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus; D002440:Cefoxitin