2007 Abstract : 12

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Author(s): N Rao, B Canella, F Hardic, J Schnebel, Pittsburgh, PA

Title: Pre-operative Eradication of Staphylococcus aureus prevents Surgical Site Infections in Patients undergoing Total Joint Arthroplasty

Purpose: To determine whether pre-operative eradication of Staphylococcus aureus (MSSA/MRSA) reduces Surgical Site Infections (SSIs) in patients undergoing Total Joint Arthroplasty (TJA).

Methods: Study period: October 2005- October 2006 Patients undergoing elective TJA by one group of orthopedic surgeons were screened for MSSA/MRSA from nasal swab specimens two weeks prior to their scheduled surgery (PTS). Patients with positive nasal swab cultures for either MSSA or MRSA were treated with: 1. Mupirocin nasal ointment to both nares, bid, for 5 days PTS 2. 2. Daily chlorhexidine baths for 5 days, PTS 3. Systemic peri-operative antibiotic prophylaxis: MSSA-positive patients: Cefazolin ¡V 2G, 30 to 60 minutes before the surgery followed by 1G q8h/24h MRSA-positive patients: Vancomycin ¡V 1G, 60 minutes before the surgery followed by 1G q12h/24h All patients were followed upto one year for evidence of MSSA/MRSA SSI. Another group of patients who did not participate (controls) were followed concurrently for evidence of SSIs.

Results: During the 12 month study period, 1906 patients underwent TJA. 636 patients were screened for MSSA/MRSA by nasal swab specimens. Remainder 1,330 patients did not participate. 147 out of 636 (23%) were positive for MSSA and 17 out of 636 (3%) were positive for MRSA, accounting for a total of 164 (26%) patients. This group of patients was treated with the protocol as outlined above. None of the patients developed post-operative MSSA/MRSA SSI followed up to one year. In contrast, 12 out of 1,330 patients who did not participate in the study developed post-operative MSSA/MRSA SSIs. Assuming that 25% of 1,330 would have been positive for MSSA/MRSA, accounts for an infection rate of 3.5% (12/345) with a p-value of 0.016 (equal variance assumed) w/a 99%CI. Cost savings in the study group accounted for $270,000 in comparison to net loss of $306,000 in the control group.

Discussion: Pre-operative eradication of MSSA/MRSA appears to prevent Staphylococcus aureus SSI in patients undergoing elective TJA. Statistically significant reduction in SSIs was noted in the study group. Net gain of $270,000 was noted in the study group in comparison to net loss of $306,000 in the control group. Further study is need to corroborate these findings.