Methicillin-Resistant Staphylococcus Species in a Cardiac Surgical Intensive Care Unit: A 5-Year Experience

Objectives: Methicillin-resistant Staphylococcus is a growing problem in intensive care units (ICUs). The aim of this study was to describe the epidemiology of methicillin-resistant Staphylococcus isolates in a cardiac surgical ICU over a 5-year period and to determine the risk factors and outcome of this condition. Methods: During the period from January 1998 to July 2003, the clinical data of all adult patients who underwent cardiac surgery in a university hospital were prospectively recorded in a database; the perioperative clinical variables and microbiologic data were studied by means of univariate and multivariate analysis in order to identify risk factors for the development of methicillin resistance and in-hospital death. Results: Methicillin-resistant Staphylococcus species strains were isolated in 118 of 6,423 patients operated on during the study period (7.6 cases per 1,000 days of ICU stay), with a constant prevalence rate throughout the years. Methicillin-resistant Staphylococcus species have been the most frequently isolated microorganisms in the authors’ ICU; 75% of Staphylococcus aureus and 95% of coagulase-negative staphylococci were methicillin resistant. In-hospital mortality in methicillin-resistant Staphylococcus –positive patients was 50.0% (59/118), whereas it was 1.7% (108/6305) in other patients ( p Staphylococcus species isolation was the single risk factor with the strongest association with in-hospital death (odds ratio, 8.5; 95% confidence interval 4.9-14.7). In the present series, there were no isolates of vancomycin-resistant species ( Enterococcus species or Staphylococcus species). Conclusions: Staphylococcus species represent the most frequently isolated microorganisms in the authors’ ICU. In-hospital mortality in cardiac surgical patients is strongly correlated to the isolation of methicillin-resistant Staphylococcus .