Peritoneal resorption capacity for the inflammatory mediators in acute experimental Staphylococcus aureus peritonitis

Elevations in both endotoxin and interleukin-6 (IL-6) concentrations in peritoneal exudates are a thousand times higher than their respective concentrations in the peripheral blood in patients with gram-positive or gram-negative peritonitis. We aimed in this study to evaluate the resorption capacity of the peritoneum for endotoxin and IL-6 in a model of bacterial (gram-positive) peritonitis.

Intraperitoneal (i.p.) injection of mucin-pretreated staphylococci in phosphate buffered saline (PBS) or of PBS alone was performed in 93 male Wistar rats. Studies of resorption were undertaken at time points of 4 hours (h), 8h, 12h and 24h. Endotoxin was intraperitoneally injected in 44 rats and IL-6 in 49 rats. After 0, 5, 10, 15, 30 and 60 minutes (min), blood was sampled. Endotoxin and IL-6 were measured using the limulus-amoebocyte-lysate (LAL) test and ELISA technique, respectively.

No endotoxin or IL-6 was measured in the blood of controls. Plasma endotoxin and IL-6 levels were significantly high in the peritonitis groups. There was no further increase in endotoxin plasma levels after i.p. injection of endotoxin. Following i.p. injection of IL-6, there was an increase in IL-6 level over the time of sampling in the peripheral blood at 4h of peritonitis.

There was a clear reduction in peritoneal resorption of endotoxin and IL-6 in this acute model of gram-positive peritonitis.