Staphylococcus aureus is a common cause of nosocomial infection, and the risk is known to be several-fold higher in patients who are chronically colonized with this organism in the anterior nares. In a randomized, double-blind, placebo-controlled trial, Perl and colleagues examined the preoperative use of intranasal mupirocin to prevent nosocomial S. aureus infections.

The investigators enrolled patients who underwent elective and nonemergency surgical procedures (e.g., cardiothoracic, general, gynecologic, oncologic, or neurologic). Of the 5,257 patients initially screened, informed consent was available from 4,030 subjects (76.7 percent); of these, 166 were excluded because they were not undergoing one of the selected procedures or did not receive mupirocin. The 3,864 enrolled subjects were randomized to receive topical mupirocin or placebo application via cotton swab to the anterior nares twice daily for up to five days before the surgery. Most participants received at least three doses of the study medication preoperatively. All enrollees were followed for 30 days after surgery to determine the incidence of postoperative infection caused by S. aureus.

The overall rate of S. aureus infection was not significantly different between patients receiving mupirocin (2.3 percent) versus patients receiving placebo (2.4 percent). However, in patients shown to be colonized with S. aureus by preoperative nasal culture (23 percent of subjects), the rate of S. aureus infection was 4.0 percent of patients receiving mupirocin and 7.7 percent of patients receiving placebo. Carriage of S. aureus was eliminated in 81.3 percent of carriers who received three to five doses of mupirocin, and in 93.3 percent of patients who received six or more doses of mupirocin. Nasal carriage of S. aureus was eliminated in 27.4 percent of patients who received placebo.

The authors concluded that universal pre-operative use of intranasal mupirocin did not decrease the overall rate of S. aureus infections at surgical sites, but it did reduce the rate of nosocomial S. aureus infections in patients known to have nasal carriage of the organism.