Strain Differences in the Opsonisation of Staphylococcus Epidermidis

UK Ten isolates of coagulase-negative staphylococci, collected from patients receiving treatment with continuous ambulatory peritoneal dialysis (CAPD), exhibited marked differences in the degree of opsonisation when incubated in 10 % and 1 % pooled human serum, 10 % and 1 % heat-treated serum, Hanks ' Balanced Salt Solution, and timed peritoneal dialysis (PD) effluent. The addition of exogenous IgG to PD effluent results in a greater in-crease in opsonisation in those fluids with the weakest inherent opsonic activity, but is ineffective against the majority of isolates in the absence of heat-Iabile opsonic activity. The results of this in vitro study suggest that host resistance to CAPD peritonitis due to coagulasenegative staphylococci may be determined as much by the characteristics of the contaminating strain, as by the opsonising activity of PD effluent. KEY WORDS: Chemiluminescence; complement; IgG