摘要：The objective of this study was to evaluate the incidence of infection and the risk factors associated to bacteraemia and mortality due to methicillin-resistant Staphylococcus aureus (MRSA). This cohort study, conducted from August 2004 through November 2005, involved 60 consecutively identified patients with bloodstream MRSA infection. The control group included 240 non-infected patients, randomly selected and hospitalized on the day, or immediately after, results of blood culture of case patients were available. A case-control (1:4) study was conducted for evaluation of risk factors for bacteraemia and death. The incidence of infection was 1.99/1000 admissions. Mortality rates were 30% among patients and 5.38% among controls, with an attributed death rate of 24.6%. Multivariate analysis indicated the following risk factors for bacteraemia: severity predictors McCabe = 1, ASA>2 or APACHE II>10 (OR: 4.1, 95% CI: 1.8-9.4) and use of central venous catheter (OR: 7.3, 95% CI: 2.4-22.2). Univariate analysis showed as risk factors for mortality: age (OR: 1.08, 95% CI: 1.03-1.12), severity predictors McCabe = 1, ASA>2 or APACHE II>10 (OR: 9.13, 95% CI: 2.57-32.35), use of mechanical ventilation (OR: 10.32, 95% CI: 1.78-59.51) and use of corticoids (OR: 9.96, 95% CI: 2.69-36.78). Present results when investigating risk factors for bacteremia and mortality due to MRSA showed moderate influence of control group selection, in comparison to studies in which methicillin-sensitive S. aureus infection is used as control.
