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March 2011

Local Antibiotics to Prevent Surgical Site Infections: Another Zeno's Paradox?

Author Affiliations

Author Affiliation: Cardiothoracic Surgery, NIH Heart Center at Suburban Hospital, Bethesda, Maryland.

Arch Surg. 2011;146(3):359-360. doi:10.1001/archsurg.2011.21


Effect of an Implantable Gentamicin-Collagen Sponge on Sternal Wound Infections Following Cardiac Surgery: A Randomized Trial

Elliott Bennett-Guerrero, MD; T. Bruce Ferguson Jr, MD; Min Lin, PhD; Jyotsna Garg, MS; Daniel B. Mark, MD, MPH; Vincent A. Scavo Jr, MD; Nicholas Kouchoukos, MD; John B. Richardson Jr, MD; Renee L. Pridgen, BS; G. R. Corey, MD; for the SWIPE-1 Trial Group

Context:   Despite the routine use of prophylactic systemic antibiotics, sternal wound infection still occurs in 5% or more of cardiac surgical patients and is associated with significant excess morbidity, mortality, and cost. The gentamicin-collagen sponge, a surgically implantable topical antibiotic, is currently approved in 54 countries. A large, 2-center, randomized trial in Sweden reported in 2005 that the sponge reduced surgical site infection by 50% in cardiac patients.

Objective:   To test the hypothesis that the sponge prevents infection in cardiac surgical patients at increased risk for sternal wound infection.

Design, Setting, and Participants:   Phase 3 single-blind, prospective randomized controlled trial, 1502 cardiac surgical patients at high risk for sternal wound infection (diabetes, body mass index >30, or both) were enrolled at 48 US sites between December 21, 2007, and March 11, 2009.

Intervention:   Single-blind randomization to insertion of 2 gentamicin-collagen sponges (total gentamicin of 260 mg) between the sternal halves at surgical closure (n = 753) vs no intervention (control group: n = 749). All patients received standardized care including prophylactic systemic antibiotics and rigid sternal fixation.

Main Outcome Measures:   The primary end point was sternal wound infection occurring through 90 days postoperatively as adjudicated by a clinical events classification committee blinded to study treatment group. The primary study comparison was done in the intent-to-treat population. Secondary outcomes included (1) superficial wound infection (involving subcutaneous tissue but not extending down to sternal fixation wires), (2) deep wound infection (involving the sternal wires, sternal bone, and/or mediastinum), and (3) score for additional treatment, presence of serous discharge, erythema, purulent exudate, separation of the deep tissues, isolation of bacteria, and duration of inpatient stay (ASEPSIS; minimum score of 0 with no theoretical maximum).

Results:   Of 1502 patients, 1006 had diabetes (67%) and 1137 were obese (body mass index >30) (76%). In the primary analysis, there was no significant difference in sternal wound infection in 63 of 753 patients randomized to the gentamicin-collagen sponge group (8.4%) compared with 65 of 749 patients randomized to the control group (8.7%) (P = .83). No significant differences were observed between the gentamicin-collagen sponge group and the control group, respectively, in superficial sternal wound infection (49/753 [6.5%] vs 46/749 [6.1%]; P = .77), deep sternal wound infection (14/753 [1.9%] vs 19/749 [2.5%]; P = .37), ASEPSIS score (mean [SD], 1.9 [6.4] vs 2.0 [7.2]; P = .67), or rehospitalization for sternal wound infection (23/753 [3.1%] vs 24/749 [3.2%]; P = .87).

Conclusion:   Among US patients with diabetes, high body mass index, or both undergoing cardiac surgery, the use of 2 gentamicin-collagen sponges compared with no intervention did not reduce the 90-day sternal wound infection rate.

Trial Registration:   clinicaltrials.gov Identifier: NCT00600483

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