Plasmid-Encoded Transferable mecB-Mediated Methicillin Resistance in Staphylococcus aureus

Emerg Infect Dis. 2018 Feb;24(2):242-248. doi: 10.3201/eid2402.171074.


During cefoxitin-based nasal screening, phenotypically categorized methicillin-resistant Staphylococcus aureus (MRSA) was isolated and tested negative for the presence of the mecA and mecC genes as well as for the SCCmec-orfX junction region. The isolate was found to carry a mecB gene previously described for Macrococcus caseolyticus but not for staphylococcal species. The gene is flanked by β-lactam regulatory genes similar to mecR, mecI, and blaZ and is part of an 84.6-kb multidrug-resistance plasmid that harbors genes encoding additional resistances to aminoglycosides (aacA-aphD, aphA, and aadK) as well as macrolides (ermB) and tetracyclines (tetS). This further plasmidborne β-lactam resistance mechanism harbors the putative risk of acceleration or reacceleration of MRSA spread, resulting in broad ineffectiveness of β-lactams as a main therapeutic application against staphylococcal infections.

Keywords: MRSA; Macrococcus; Staphylococcaceae; Staphylococcus aureus; antibacterial agents; antimicrobial resistance; bacteria; mecB; methicillin-resistant Staphylococcus aureus; microbial genome; plasmids; staphylococci.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Bacterial Proteins / genetics*
  • Gene Transfer, Horizontal
  • Humans
  • Male
  • Methicillin Resistance / genetics*
  • Methicillin-Resistant Staphylococcus aureus / genetics*
  • Plasmids / genetics*


  • Bacterial Proteins