Eradication of Staphylococcus aureus post-sternotomy mediastinitis following the implementation of universal pre-operative nasal decontamination with mupirocin: an interrupted time-series analysis.

BACKGROUND Although pre-surgical nasal decontamination with mupirocin (NDM) has been advocated as a measure for preventing post-surgical mediastinitis (PSM) due to Staphylococcus aureus, this strategy is not universally recommended due to the lack of robust supporting evidence. We aimed to evaluate the role of pre-operative NDM in the annual incidence of S. aureus PSM at our institution. METHODS An interrupted time-series analysis, with autoregressive error model, was applied to our single-center cohort by comparing pre-intervention (1990-2003) and post-intervention period (2005 to 2018). Logistic regression was performed to analyze risk factors for S. aureus PSM. FINDINGS 12,236 sternotomy procedures were analyzed (6,370 [52.1%] and 5,866 [47.9%] in the pre-intervention and post-intervention periods, respectively). The mean annual percentage adherence to NDM estimated over the post-interventional period was 90.2%. Only four out of 127 total cases of S. aureus PSM occurred during the 14-years post-intervention period (0.68/1,000 sternotomies vs. 19.31/1,000 in pre-interventional period [p<0.0001]). Interrupted time-series analysis demonstrated a statistically significant annual reduction of S. aureus PSM trend of -9.85 cases per 1,000 sternotomies (-13.17 to -6.5, P-value< 0·0001) in 2005, with a decreasing trend maintained over the following five years with an estimated relative reduction of 84.8% (95% CI: 89·25 to 74·09). Chronic obstructive pulmonary disease was the single independent risk factor for S. aureus PSM (odds ratio: 3.7; 95% CI: 1.72-7.93) and was equally distributed in patients undergoing sternotomy during pre or post-intervention periods. INTERPRETATION Our experience suggests that the implementation of pre-operative NDM reduces significantly the incidence of S. aureus PSM.