Mupirocin ointment for preventing Staphylococcus aureus infections in nasal carriers

Background: Staphylococcus aureus (S. aureus) is the leading nosocomial (hospital acquired) pathogen in hospitals throughout the world. Traditionally, control of S. aureus has been focused on preventing cross-infection between patients, however, it has been shown repeatedly that a large proportion of nosocomial S. aureus infections originate from the patient's own flora. Nasal carriage of S. aureus is now considered a well defined risk factor for subsequent infection in various groups of patients. Local antibiotic treatment with mupirocin ointment is often used to eradicate nasal S. aureus. Objectives: To determine whether the use of mupirocin nasal ointment in patients with identified S. aureus nasal carriage reduced S. aureus infection rates. Search strategy: We searched the Cochrane Wounds Group Specialised Register (May 2008), the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 2 2008), MEDLINE (1950 to May 2008), EMBASE (1980 to May 2008) and CINAHL (1982 to May 2008). To identify unpublished trials, abstract books from major scientific meetings (ICAAC, ESCMID and SHEA) were handsearched, researchers and manufacturers of mupirocin were contacted and other electronic databases were searched (SIGLE, ASLIB Index, mRCT, USA Clinical Trials). Selection criteria: Randomised controlled trials (RCTs) comparing nasal mupirocin with no treatment or placebo or alternative nasal treatment in the prevention of S. aureus infections in nasal S. aureus carriers were included. Data collection and analysis: Titles, abstracts and full-text articles of studies retrieved from the search process were independently assessed by two authors for inclusion. From included studies a data extraction form was made and the quality of the trial was assessed. The primary outcome was the S. aureus infection rate (any site). Secondary outcomes were time to infection, mortality, adverse events and infection rate caused by micro-organisms other than S. aureus. Main results: Nine RCTs involving 3396 participants met the inclusion criteria. Patient populations varied and several types of nosocomial S. aureus infection were described including bacteraemia, exit-site infections, peritonitis, respiratory tract infections, skin infections, surgical site infections (SSI) and urinary tract infections. After pooling the eight studies that compared mupirocin with placebo or with no treatment, there was a statistically significant reduction in the rate of S. aureus infection associated with intranasal mupirocin (RR 0.55, 95% CI 0.43 to 0.70). A planned subgroup analysis of surgical trials demonstrated a significant reduction in the rate of nosocomial S. aureus infection rate associated with mupirocin use (RR 0.55, 95% CI 0.34 to 0.89) however this effect disappeared if the analysis only included surgical site infections caused by S. aureus (RR 0.63, 95% CI 0.38 to 1.04), possibly due to a lack of power. The infection rate caused by microorganisms other than S. aureus was significantly higher in patients treated with mupirocin compared with control patients (RR 1.38 95% CI 1.118 to 1.72). Authors' conclusions: In people who are nasal carriers of S. aureus, the use of mupirocin ointment results in a statistically significant reduction in S. aureus infections.