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Heterogeneity in opsonic requirements of Staphylococcus epidermidis: relative importance of surface hydrophobicity,
H van Bronswijk1, H A Verbrugh, H C Heezius
1Department of Medicine, Free University Hospital, Amsterdam, The Netherlands.
Abstract:
The opsonic requirements of 65 strains of Staphylococcus epidermidis were compared in fresh and in heated normal human serum. The strains were isolated from patients with CAPD peritonitis (n = 26), neonatal septicaemia (n = 24) and nasal cultures (n = 15). A wide variation was observed in opsonic requirements between the different strains, both with fresh and with heated serum. Opsonization in heated serum proceeded less efficiently and higher concentrations (mean three-fold compared to fresh serum) were needed for adequate phagocytosis. However, a highly significant correlation was found between the minimal opsonic concentrations of fresh and of heated serum (r = 0.84, P less than 0.0005). In addition, S. epidermidis can become opsonized in agammaglobulinaemic serum. Thus, opsonization of S. epidermidis can be mediated by antibodies alone and by complement alone. Slime-producing strains and encapsulated strains did not require higher concentrations of serum to become opsonized. Opsonic requirements were highly significantly correlated with surface hydrophobicity. Enzymatic treatment rendered the strains more hydrophilic and decreased their opsonic requirements. Isolates from nasal cultures required significantly higher concentrations of both fresh and heated serum to become adequately phagocytozed, whereas isolates from CAPD peritonitis required higher concentrations of heated serum only compared to blood isolates. The uptake of S. epidermidis preopsonized in heated serum as determined in our direct phagocytosis assay did not result in a comparable chemiluminescence response.
Insights
Staphylococcus epidermidis opsonization can be mediated by antibodies or complement alone, with varying requirements based on strain source and surface properties. Opsonic needs correlate with hydrophobicity, impacting phagocytosis efficiency.
Area of Science:
- Immunology
- Microbiology
- Infectious Diseases
Background:
- Staphylococcus epidermidis is a common cause of healthcare-associated infections.
- Understanding its opsonization is crucial for effective immune response and treatment strategies.
- Opsonic requirements vary significantly among different strains and infection sources.
Purpose of the Study:
- To compare the opsonic requirements of Staphylococcus epidermidis strains from various clinical sources.
- To investigate the roles of antibodies and complement in S. epidermidis opsonization.
- To explore the influence of bacterial surface characteristics on opsonization efficiency.
Main Methods:
- Comparison of opsonization in fresh and heated normal human serum across 65 S. epidermidis strains.
- Isolation of strains from patients with CAPD peritonitis, neonatal septicaemia, and nasal cultures.
- Assessment of opsonic requirements correlated with surface hydrophobicity and enzymatic treatments.
Main Results:
- Significant variation in opsonic requirements observed among strains.
- Opsonization in heated serum was less efficient, requiring higher concentrations.
- Opsonic requirements strongly correlated with surface hydrophobicity; increased hydrophilicity decreased requirements.
Conclusions:
- Opsonization of S. epidermidis can be mediated by antibodies or complement independently.
- Nasal isolates showed higher serum requirements, while CAPD peritonitis isolates had specific needs for heated serum.
- Surface hydrophobicity is a key factor influencing S. epidermidis phagocytosis.