Context: The aim of this study was to investigate the methicillin-resistant Staphylococcus aureus (MRSA) clones isolated in a Dutch university hospital, situated near the borders of Belgium and Germany, between 2002 and 2006. MRSA strains (n = 175) were characterized using spa and SCCmec typing. The presence of Panton Valentine leukocidin (PVL) was determined. Between 2002 and 2005, ST5-MRSA-IV was predominant, and the spa type of ST5-MRSA-IV changed from t002 to t447. ST5-MRSA-I, ST5-MRSA-II, ST228-MRSA-I, and ST247-MRSA-I were also observed in this period. From 2004, the MRSA genetic background became more diverse, and in 2006, ST5-MRSA-IV was only sporadically observed. From 2005, ST5-MRSA-II, ST8-MRSA-IV, ST22-MRSA-IV, and ST45-MRSA-IV were increasingly observed. Several other MRSA clones, such as ST239-MRSA-III, were found sporadically. Four PVL-positive MRSA isolates were observed, associated with ST80-MRSA-IV and ST8-MRSA-IV. ST5-MRSA-I, ST5-MRSA-II, ST5-MRSA-IV, and ST228-MRSA-I have not been described previously in The Netherlands. 
 Question: What is MRSA?
mrsa methicillin-resistant s. aureus