This study was designed to evaluate the effect of a targeted preoperative Methicillin-resistant Staphylococcus aureus (MRSA) detection by polymerase chain reaction (PCR) on either endogenous or exogenous postoperative MRSA infections in a high risk population undergoing gastroenterological surgery. The primary endpoint was to investigate whether the potentially high incidence of MRSA infections in patients with MRSA nasal colonization before surgery can be prevented with a PCR-based strategy. The second endpoint was to investigate the impact of acquisition of MRSA colonization after surgery on the occurrence of MRSA infections. Investigators hypothesize that postoperative MRSA infection is prevented by a targeted screening strategy in preoperative MRSA carrier, and there is limited effect in patients with postoperative MRSA acquisition.

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.

Control measures in identified MRSA carriers consisted of contact precautions, antibiotic prophylaxis with a single dose of vancomycin 1g in addition to cephalosporins, and topical decolonization of MRSA (application of 2% mupirocin ointment twice daily to nares for 5 days and a bath with 4% chlorhexidine daily for 3-5 days). Although contact precautions were used when caring for MRSA-colonized patients, isolation/cohorting was not routinely practiced.

Inclusion Criteria:

• patients undergoing inflammatory bowel disease (IBD) surgery
• patients undergoing major hepato-biliary-pancreatic surgery

Exclusion Criteria:

• emergency surgery,
• age less than 18 years old
• known allergy to mupirocin or chlorhexidine.