Development of an in-vitro model to study the growth characteristics of Staphylococcus epidermidis in continuous...

An in-vitro model of peritonitis in continuous ambulatory peritoneal dialysis (CAPD) has been developed which integrates the parameters of environmental gaseous tension, the changing biochemical profile of the dialysate, and the periodic challenge of fresh fluid. Dwell times of 4 h during the day and 10 h at night were used to reflect the in-vivo situation. Biochemical analysis of dialysate within the model showed that the profiles for creatinine, glucose and protein approximated those found in patients. Staphylococcus epidermidis growing in synthetic dialysis effluent or pooled dialysis fluid were seen to adapt rapidly to the environment after an initial lag phase; a tendency to aggregate together increased over the 50-h period of operation. In conclusion, the results presented here suggest that this in-vitro model creates an environment which is reflective of the in-vivo situation and therefore has potential for the study of peritonitis in CAPD.