Heterogeneity of methicillin-resistant Staphylococcus aureus isolated in Norway

Our objective was to look for differences in susceptibility patterns between Norwegian and imported methicillin-resistant Staphylococcus aureus (MRSA) strains. All MRSA isolates from the participating hospitals (87 isolates from 81 patients) throughout the period 1994-98 were examined, to study the clonal distribution of MRSA isolated in Norway and to identify any epidemic clones among the isolates. We found that imported isolates were resistant to an average of 5.6 antibiotics, while Norwegian isolates were resistant to an average of 2.6 antibiotics. MRSA isolates imported to Norway are more often multiresistant than domestic isolates. MRSA isolates in Norway show a striking diversity. Epidemic clones are present, but no single clone is predominant.