Opsonic activity of dialysis effluent predicts those at risk of Staphylococcus epidermidis peritonitis

The overnight effluent obtained from 62 patients undergoing CAPD was examined for IgG, C3 and C4 concentrations and for opsonic activity against S. epidermidis using polymorphonuclear leucocyte phagocytosis and luminol-dependent. chemiluminescence. There was a negative correlation between IgG and the age of the patient, but no relationship between IgG, C3 and C4, time on CAPD, or clinical diagnosis. Forty-eight of these patients were followed up for 6 months and 37 for a full year. An effluent IgG concentration of less than 0.105 g/l was associated with a significantly greater risk of infection with S. epidermidis during the study period. Comparing 'high' and 'low' values of C3 and C4, and using phagocytosis and chemiluminescence as measures of opsonic activity there were significant differences in the frequency of S. epidermidis peritonitis between the two groups during the follow up periods. No patient with high values of both IgG and C3 had S. epidermidis peritonitis during 12 months of study. Opsonic activity was both immunoglobulin and complement dependent. The latter activity involved both the classical and alternative complement pathways. These results suggest that routine screening of dialysate for IgG and C3 concentrations may be of prognostic value.