Strain differences in the opsonisation of Staphylococcus epidermidis.

Area of Science:

• Microbiology
• Immunology
• Nephrology

Background:

• Coagulase-negative staphylococci (CoNS) are a significant cause of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).
• Understanding the host-pathogen interactions, particularly opsonisation, is crucial for preventing and managing CAPD peritonitis.

Purpose of the Study:

• To investigate the opsonisation of CoNS isolates from CAPD patients using various biological fluids.
• To determine the role of heat-labile and heat-stable factors in PD effluent and serum on CoNS opsonisation.

Main Methods:

• Ten CoNS isolates from CAPD patients were incubated in different opsonising media: pooled human serum (10% and 1%), heat-treated serum (10% and 1%), Hanks' Balanced Salt Solution, and PD effluent.
• The effect of adding exogenous IgG to PD effluent was assessed.
• Opsonisation levels were evaluated based on the observed differences in these conditions.

Main Results:

• Significant variations in opsonisation were observed among CoNS isolates across different incubation fluids.
• Exogenous IgG enhanced opsonisation in fluids with weak inherent activity.
• However, IgG addition was ineffective against most isolates without heat-labile opsonising factors.

Conclusions:

• Host resistance to CoNS peritonitis in CAPD patients may depend on both the intrinsic characteristics of the infecting CoNS strain and the opsonising capacity of the peritoneal dialysis effluent.
• The presence of heat-labile opsonising factors is critical for effective host defence against these infections.