Blot et al determined attributable mortality in critically ill patients with methicillin-susceptible (n = 38) and methicillin-resistant (n = 47) Staphylococcus aureus bacteremia. Therefore, 2 independent case-control studies were performed, after which attributable mortality rates were compared. Methicillin-susceptible S aureus bacteremia was associated with an attributable mortality rate of 1.3%, since mortality rates for cases and controls were, respectively, 23.7% vs 22.4%. Methicillin-resistant S aureus bacteremia had an attributable mortality rate of 23.4%, since mortality rates in cases and controls were, respectively, 63.8% vs 40.4%. The difference between both attributable mortality rates (22.1%) was significant (95% confidence interval, 8.8%-35.3%).