Minimizing surgical-site infections.

Primitive ancestors of Homo sapiens and their colonizing bacteria have coevolved for approximately 500,000 years; some experts estimate that the total number of human cells is 1013 and the total number of colonizing microbes is 1014. Despite this 10-to-1 inequity, the balance of power is influenced by an intact human immune system and the integrity of the skin and mucous membranes. Operative procedures disrupt this balance, resulting in a risk of surgical-site infections from endogenous flora, including colonizing strains of Staphylococcus aureus. Each year in the United States, more than 30 million operative procedures are performed. The risk of infection depends on the skill of the surgeon, the degree of contamination defined by the type of surgery (i.e., clean, clean-contaminated, or contaminated), and the patient’s status with respect to underlying coexisting conditions and carriage of S. aureus. Approximately 20 to 30% of surgical-site infections are caused by S. aureus, and over half of these arise from the endogenous flora. In an attempt to reduce surgical morbidity, the Surgical Infection Prevention Project and the Surgical Care Improvement Project have outlined evidence-based recommendations, bundling several strategies into a comprehensive approach. They include the initial administration of perioperative antibiotics within 1 hour before surgery, the preoperative use of hair clippers or no hair removal (as opposed to shaving of hair), and the maintenance of normothermia during colorectal surgery.1 Because S. aureus is a virulent pathogen that can cause surgical-site infections, some studies have focused on eliminating nasal carriage of this organism preoperatively. Results of a recent metaanalysis suggested that topical mupirocin applied intranasally would reduce the rate of surgical-site infections due to S. aureus by 45% in the subgroup of patients who are carriers.2 It is also known that the skin is an important extranasal reservoir not only for S. aureus but also for other organisms implicated in postoperative infections. Two well-controlled, multicenter, randomized studies reported in this issue of the Journal offer valuable insights for controlling surgical-site infections. Bode and colleagues demonstrated the efficacy of rapid, preoperative screening for nasal carriage of S. aureus along with the prophylactic treatment of patients who had positive results with the use of intranasal mupirocin twice a day for 5 days and daily baths with chlorhexidine soap.3 Patients scheduled to undergo simple operative procedures were excluded, and only those who were expected to remain in the hospital for at least 4 days were randomly assigned to either active treatment or placebo. The subgroup of surgical-site infections caused by S. aureus was reduced by 60% among those in the active treatment group as compared with those treated with the placebo nasal ointment plus placebo soap. In the second study, Darouiche and colleagues found a greater than 40% reduction in total surgical-site infections among patients undergoing clean-contaminated surgery who had received a single chlorhexidine–alcohol scrub as compared with a povidone–iodine scrub.4 No patients received intranasal mupirocin in this study, yet the rate of S. aureus surgical-site infections was reduced by approximately 50% in the chlorhexidine–alcohol group (see the Supplementary Appendix to the article by Darouiche et al., available at NEJM.org). Chlorhexidine–alcohol has been recommended by the Centers for Disease Control and Preven-