Methicillin-resistant Staphylococcus aureus as a causative agent of postoperative intra-abdominal infection: Relation to nasal colonization

In the surgical intensive care unit of a university hospital, we investigat ed the frequency of and the risk factors for acquisition of methicillin-res istant Staphylococcus aureus (MRSA) during postoperative intra-abdominal in fection (pIAI). We conducted a prospective MRSA nasal screening and case ev aluation for 17 months among 73 consecutive patients with having pIAI. MRSA pIAI was diagnosed when MRSA was obtained from culture of intraperitoneal fluids. The identity of nasal and peritoneal MRSA strains was assessed by g enomic analysis. Twelve patients had MRSA pIAI, representing 21% of all MRS A infections acquired by the 73 patients. An organ system failure score of greater than or equal to 1 and MRSA nasal carriage prior to pIAI were the i ndependent risk factors for acquisition of MRSA pIAI, Patients with MRSA pI AI had a longer intensive care unit stay and more reoperations than did tho se free of MRSA pIAI. We conclude that MRSA may be a causative pathogen in pIAI and may be related to nasal colonization.