Staphylococcus aureus colonization among arthroplasty patients previously treated by a decolonization protocol: a pilot study.

Although testing and treatment for Staphylococcus aureus colonization before total joint arthroplasty (TJA) are well described and understood, the durability of decolonization has not been studied extensively. The purpose of this pilot study is to determine the percentage of arthroplasty patients with S. aureus colonization despite previous decolonization at the time of TJA. Over a 2-year period, all patients having TJA by one surgeon were screened and treated for nasal S. aureus. Of 634 patients, 139 had methicillin-sensitive S. aureus (15%) or methicillin-resistant S. aureus (6.6%) colonization before TJA. Fifty-eight of these 139 patients (42%) were retested at 3 to 30 months for persistent colonization by nasal culture. Data collection included age at time of TJA, type of TJA, and time from TJA to repeat testing. We performed no clonal analysis for strains. Thirty-nine of the 58 patients (67%) decolonized before surgery were negative on retesting and 19 (33%) were again positive for S. aureus colonization. Of the 19 patients who retested positive for colonization, 17 (89%) were colonized by bacteria with unchanged antibiotic sensitivity. We demonstrate that 33% (19 of 58) of postoperative arthroplasty patients test positive for S. aureus colonization at 3 to 30 months after surgery despite preoperative decolonization. Arthroplasty surgeons must be aware that a decolonization treatment does not guarantee that a patient will remain decolonized in the future. Although unchanged antibiotic sensitivity in 89% of these patients suggests a substantial role for persistence as opposed to eradication and repeat colonization, we were unable to retrospectively perform clonal analysis to confirm this conclusion. This group of patients demonstrating continued colonization with S. aureus after arthroplasty deserves further study, because it remains unclear whether there is a higher risk of late infection in this population. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.