Abstract: We located two studies (291 participants) for inclusion in this review. The trials were clinically heterogeneous with differences in duration of follow-up, and nasal decontamination regimens. One study compared mupirocin (2% contained in a base of polyethylene glycol 400 and polyethylene glycol 3350) with a placebo in elective cardiac surgery patients; and one study compared Anerdian (iodine 0.45% to 0.57% (W/V), chlorhexidine acetate 0.09% to 0.11% (W/V)) with no treatment also in cardiac surgery patients. The trials reported limited outcome data on SSI, adverse events and secondary outcomes (e.g. S aureus SSI, mortality). Mupirocin compared with placebo This study found no clear difference in SSI risk following use of mupirocin compared with placebo (1 trial, 257 participants); risk ratio (RR) 1.60, 95% confidence interval (CI) 0.79 to 3.25 based on 18/130 events in the mupirocin group and 11/127 in the control group; low-certainty evidence (downgraded twice due to imprecision). Anerdian compared with no treatment It is uncertain whether there is a difference in SSI risk following treatment with Anerdian compared with no treatment (1 trial, 34 participants); RR 0.89, 95% CI 0.06 to 13.08 based on 1/18 events in the Anerdian group and 1/16 in the control group; very low certainty evidence (downgraded twice due to imprecision and once due to risk of bias). There is currently limited rigorous RCT evidence available regarding the clinical effectiveness of nasal decontamination in the prevention of SSI. This limitation is specific to the focused question our review addresses, looking at nasal decontamination as a single intervention in participants undergoing surgery who are known S aureus carriers. We were only able to identify two studies that met the inclusion criteria for this review and one of these was very small and poorly reported. The potential benefits and harms of using decontamination for the prevention of SSI in this group of people remain uncertain.

Plain-language summary: In September 2016 we searched for randomised controlled trials (RCTs) involving nasal decontamination for preventing SSI. We included two studies with 291 participants, all adults undergoing cardiac surgery. The anti-bacterial products used for cleaning the nose were mupirocin (antibiotic cream) and Anerdian (disinfectant solution). It is unclear whether nasal decontamination makes a difference to the rate of SSI in people carrying S aureus bacteria. S aureus SSI was reported in only one trial and the results do not allow us to be certain about differences in infection rates. Some participants in the Anerdian study reported side effects such as itching around the nose, but these were not serious. Mortality was low where reported (one death was directly related to S aureus infection). The two studies we found did not have many participants and the results were inconclusive. The Anerdian study report did not provide information about how the trial was conducted and this makes it difficult to be sure if it was at risk of bias. The mupirocin study was of better quality and at low risk of bias; but the small number of participants and limited effects affect the quality of the results. Evidence of the potential benefits and harms of using nasal decontamination for the prevention of SSI is currently of low to very low certainty. Larger, better-reported RCTs are needed to assess the clinical effectiveness of this treatment. This plain language summary is up to date as of September 2016.