Preop application of mupirocin cuts infections.(Clinical Rounds)

WASHINGTON -- Mupirocin ointment applied to the front of the nostrils before surgery may decolonize patients and reduce the incidence of surgical site infections from Staphylococcus aureus, said Dr. Trish M. Perl at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.

Although the Food and Drug Administration has not approved mupirocin for that purpose, several studies have found it to be effective, Dr. Perl said.

The largest investigation was the Mupirocin and the Risk of Staphylococcus aureus (MARS) study, a randomized, double-blind, placebo-controlled trial conducted by Dr. Perl and her colleagues. It enrolled 4,030 adult patients hospitalized for cardiothoracic surgery, neurosurgery, or general surgery at the University of Iowa and its associated Veterans Affairs hospital. Half of the patients were randomized to preoperative mupirocin and half to placebo. A total of 1,763 mupirocin patients and 1,809 placebo patients completed the trial (N. Engl. J. Med. 2002;346:1871-7).

The patients with preoperative S. aureus nasal carriage who were treated with one dose of mupirocin showed a nasal carriage eradication rate of nearly 80%. If patients received at least six doses before they underwent surgery, the eradication rate topped 90%. "There was a dose response in terms of the ability to decolonize," she said.

The preoperative S. aureus nasal carriers included 444 patients in the mupirocin group and 447 patients in the placebo group. Although the overall nosocomial infection rate was similar between these two groups--13% in the mupirocin group and 16% in the placebo group--there was a statistically significant 50% reduction in S. aureus-specific nosocomial infections in patients pretreated with mupirocin. Nosocomial infections included infections of the bloodstream, respiratory tract, catheter, and surgical site.

Of the 82 people who developed S. aureus-related surgical site infections, 37 (45%) had S. aureus preoperatively, and 27 of these were infected with their own strain. Fewer of those infected with their ...