Genetic Diversity among Staphylococcus aureus Isolates Showing Oxacillin and/or Cefoxitin Resistance Not Linked to the Presence of mec Genes

Methicillin-resistant Staphylococcus aureus isolates lacking mec genes ( n = 32), collected from Belgian hospitals, were characterized for their β-lactamase production and the presence of mutations in pbp genes, the pbp4 promoter, and genes involved in penicillin-binding protein 4 overproduction ( gdpP and yjbH ). Twelve isolates were β-lactamase hyperproducers (BHPs), while 12 non-BHP isolates might produce an incomplete GdpP protein. Most...