Target screening for nasal carriage of MRSA by polymerase chain reaction (PCR) was performed before or on admission. In order to identify MRSA nasal acquisition while on the ward, all patients who were negative before surgery were re-screened every 7 days until discharge. The inclusion criteria for screening were patients undergoing inflammatory bowel disease surgery on ward A, and those undergoing major hepato-biliary-pancreatic surgery on ward B. Investigators classified enrolled patients into preoperative MRSA nasal carriage, postoperative nasal acquisition in patients who were negative for PCR assay before surgery, and non-nasal MRSA carriage during hospitalization. Development of postoperative infections caused by MRSA was assessed according to the nasal MRSA carriage status. MRSA infections rate was also compared between the 2-years of the intervention period and the previous 2-year control period on each ward.