The epidermo-peritoneal potential in patients treated with continuous ambulatory peritoneal dialysis.

At physiologic pH, S. epidermidis moves along an electrical potential gradient. We measured the epidermo-peritoneal electrical potential (EPP) in 23 end-stage renal failure patients treated with CAPD. There was a negative correlation between the mean EPP and the patient's age (r = 0.47, p = 0.016), but no correlation between the mean EPP and the duration of treatment (r = 0.003, p = 0.5). The EPP was greater in those patients with a history of recurrent bacterial peritonitis due to S. epidermidis [median EPP 23 mv (95% confidence limits 16-51)] compared to those with only one or no episodes of bacterial peritonitis due to S. epidermidis infection [11 mv (9-17), p < 0.05]. Thus electrical gradients caused by the presence of the CAPD catheter could contribute to colonisation and subsequent infection by skin commensals, by aiding bacterial migration.