Rapid detection, differentiation and typing of methicillin-resistant Staphylococcus aureus harbouring either mecA or the new mecA homologue mecA(LGA251)

Clin Microbiol Infect. 2012 Apr;18(4):395-400. doi: 10.1111/j.1469-0691.2011.03715.x.


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.

Publication types

  • Validation Study

MeSH terms

  • Bacterial Proteins / genetics*
  • Base Sequence
  • Cefoxitin / pharmacology
  • Chromosomes, Bacterial / genetics
  • Conserved Sequence
  • DNA, Bacterial / analysis
  • DNA, Bacterial / genetics
  • Genes, Bacterial*
  • Humans
  • Methicillin-Resistant Staphylococcus aureus / classification
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Methicillin-Resistant Staphylococcus aureus / genetics
  • Methicillin-Resistant Staphylococcus aureus / isolation & purification*
  • Multilocus Sequence Typing / methods*
  • Multilocus Sequence Typing / standards
  • Penicillin-Binding Proteins
  • Phenotype
  • Staphylococcal Infections / genetics
  • Staphylococcal Infections / microbiology


  • Bacterial Proteins
  • DNA, Bacterial
  • Penicillin-Binding Proteins
  • mecA protein, Staphylococcus aureus
  • Cefoxitin