Genetic diversity among staphylococcus aureus isolates showing oxacillin and/or cefoxitin resistance not linked to the presence of mec genes

Abstract

Methicillin-resistant Staphylococcus aureus isolates lacking mec genes (n 32), collected from Belgian hospitals, were characterized for their -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 -lactamase hyperproducers (BHPs), while 12 non-BHP isolates might produce an incomplete GdpP protein. Most isolates showed nucleotide mis-sense mutations in pbp genes. A few isolates also showed mutations in the pbp4 promoter.