Thus, 660 000 cases

of sepsis occur in the United States each year, and combined with the high mortality, it ranks as a leading cause of death. Staphylococci, including methicillin-resistant Staphylococcus aureus, have become the most frequently isolated bacteria in nosocomial infections, giving rise, according to some reports, to more than 50% of the cases (Bearman & Wenzel, 2005). Severe sepsis occurs when sepsis (the combined events of infection and the systemic inflammatory response syndrome, i.e. SIRS) is complicated by organ dysfunction, hypotension or hypoperfusion; septic shock is characterized by persistent arterial hypotension despite adequate fluid resuscitation (Bone et al., 1992; Levy et al., 2003). The Sequential Organ Failure Assessment (SOFA) score, which evaluates the respiratory, blood clotting, hepatic, cardiovascular, central nervous and renal systems, has been advocated as a simple (bedside) method to monitor organ BMN 673 molecular weight dysfunction and guiding supportive therapy of critically ill patients, including those with sepsis (Vincent et al., 1996, 1998; Afessa et al., 2007). Several papers have demonstrated that the SOFA scoring system predicts mortality, which increases with an increasing

score and the number of failing organs. Dysfunction or failure of the cardiovascular system, followed by the renal and central nervous systems, had the single most serious impact on severity in patients in intensive care (Moreno et al., 1999), as also evidenced in septic shock patients, who suffer the highest mortality (Vincent et al., 2006). The mean CHIR 99021 time to reach the maximum SOFA scores was the highest for the liver; dysfunction of the liver, however, did not contribute to an increased risk of death (Moreno et al., 1999). The liver thus seems to be an organ on which the sum of ailments converges, making failure a late and secondary event. In a previous study (Nielsen et al., 2009b), we showed that an intravenous inoculation of S. aureus

in pigs induces acute pyaemia, with the formation of microabscesses in various organs 4– 6 h after the challenge. However, no mafosfamide systemic inflammatory response, and thus sepsis, was induced, probably due to the short duration of the experiment. The aim of the present study was to further characterize the pig as a model for human S. aureus-induced sepsis and severe sepsis. Therefore, the inoculated pigs in the present study were kept for up to 48 h, inoculation was repeated in some pigs and the study included the evaluation of the possible late event of liver dysfunction or failure. Details on the experimental animals, the bacterial inocula and the design of the study have been published previously (Jensen et al., 2010). Briefly, 12 clinically healthy female specific pathogen-free (SPF) Yorkshire–Landrace crossbreed 8-week-old pigs with a body weight (BW) of 20–25 kg were used. The pigs, which remained clinically healthy during the acclimatization period of 7 days, were randomly assigned to three groups.