Molecular Characterization of Methicillin-Sensitive Staphylococcus aureus Isolates from Bacteremic Patients in a Norwegian University Hospital

Staphylococcus aureus bacteremia is common in both nosocomial and community settings, and the pathogenicity of the microbe depends upon a large repertoire of virulence factors. S. aureus bacteremia isolates (n 126) were characterized using DNAmi-croarrays. Clonal complexes 5, 8, 15, 30, and 45 accounted for 74.6 % of the isolates. We identified geographical differences in dominating clones and toxin gene profiles. One isolate was methicillin resistant. Potential associations between age and geno-type were detected. Staphylococcus aureus bacteremia (SAB) is often associated withincreased morbidity and poor outcome (1, 2). The pathoge-nicity of S. aureus depends upon a large repertoire of virulence factors influenced by environmental conditions and host interac-tions (3). Associations between specific virulence factors and se-vere invasive infection still remain unclear. Our recent study genotyping SAB isolates (4) demonstrated a knowledge gap re-garding molecular epidemiology of methicillin-sensitive S. aureus (MSSA) isolates despite the increasing incidence of SAB (5). Here we conducted an extensive characterization of MSSA isolates de-tected in blood cultures using DNAmicroarrays in order to deter