Objective. Multi-drug resistant bacterial infections, in particular when Methicillin-Resistant Staphylococcus Aureus (MRSA) is involved, have become a relevant problem in both general and specialized intensive care units. The aim of this study was to identify the epidemiology of MRSA infections in a Cardiac Surgical Intensive Care Unit, to assess their impact on mortality and to identify predictors of MRSA infection and mortality in this population.

Design and settings. A 7-year observational study in a cardiac surgery teaching center.

Participants. Eight thousand, one hundred and sixty-two microbiological samples were obtained from 7,313 patients who underwent cardiac surgery in the study period.

Interventions. None.

Variables of interest and main results. Twenty-eight patients (0.38%) had MRSA infection. The most frequent site of MRSA isolation was from bronchoalveolar samples. Hospital mortality was 50% in patients with MRSA infection and 2% in patients without MRSA infection (p<0.001).

Few preoperative independent predictors of MRSA infection and hospital mortality were found at multivariate analysis. Outcomes were found to be most influenced by perioperative variables. MRSA infection was the strongest predictor of mortality, with an odds ratio of 20.5 (95% CI 4.143-101.626).

Conclusions. Methicillin-resistant Staphylococcus aureus infections following cardiac surgery still have a strong impact on the patients’ outcome. More efforts should be directed toward the development of new risk analysis models that might implement health care practices and might become precious instruments for infection prevention and control.

Key words: Methicillin-Resistant Staphylococcus Aureus, infections, cardiac surgery, mortality, intensive care, cardiac anaesthesia

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