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The effect of the number of bacteria and the volume of the inoculum was studied in an experimental infection model to establish a peritoneal dialysis model in the rat. Staphylococcus aureus was used in all experiments, and Staphylococcus epidermidis only in the volume experiments. A bacterial number between 108 and 109 colony forming units (cfu) resulted in a time-dependent decrease of bacteria collected from the peritoneal cavity. Higher concentrations resulted in the death of animals, while lower concentrations were rapidly cleared. There was a positive correlation between the volume in which 3 x 108 cfu were dissolved and the number of bacteria isolated from the peritoneal cavity 24 hours after infection. The results of this study led to an experimental dialysis model using 10 mL of dialysis fluid and 0.5 mL of a suspension containing 3 x 108 cfu of Staphylococcus aureus.

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Objective To determine the effect of dialysis fluid containing various glucose concentrations on the phagocytosis and killing of Staphylococcus aureus by rat peritoneal cells under conditions mimicking the in vivo situation. Design Phagocytosis and killing were evaluated by quantitation of the killing capacity of macrophages after in vivo phagocytosis of the bacteria as well as by an in vitro flow cytometric assay of the phagocytosis and killing of adhered bacteria by peritoneal cells. Animals Male Wistar rats. Main Outcome Measure It was expected that the intraperitoneal administration of dialysis fluid would im pair the capacity of peritoneal cells to eliminate bacteria. Results The first test revealed no effects of glucose concentration or dwell time on the killing of phagocytosed bacteria by macrophages, median percentages ranging between 29% and 64%. In the second series of experiments no effect of glucose concentration on the phagocytosis and killing of adhered bacteria was found either; however, longer dwell times significantly enhanced both the phagocytosis (at a dwell time of 1 hour, under 20%; at dwell times of 4 or 18 hours, above 20%, p < 0.02) and the killing (at a dwell time of 1 hour, under 53%; at dwell times of 4 and 18 hours, above 70%, p < 0.01). Conclusions Glucose concentration has no effect on the phagocytosis and killing of Staphylococcus aureus, whereas the dwell time significantly enhances both of these functional capacities of peritoneal cells if the bacteria are adhered to surfaces.