Requirements of Opsono-phagocytosis of staphylococci

Opsonophagocytosis of both Staph. aureus and coagulase negative staphylococci was studied in 46 strains from different sources of infection. Opsonophagocytosis was found to be mediated by the antibody and complement [in normal human serum] but could be also mediated by antibody alone in absence of the complement [in heated serum]. Also, it could be mediated by the complement alone in the absence of the antibody [in absorbed serum]. Coagulase negative staphylococci was more susceptible to opsonophagocytosis than Staph. aureus strains. No difference in opsonophagocytosis was found according to difference of sources of isolation

In vitro effect of intravenous immunoglobulin on serum opsonic activity in normal & intrauterine growth retarded neonates.

In vitro effect of intravenous immunoglobulin (IVIG), Intraglobin F, on serum opsonic activity against Staphylococcus aureus was studied in 26 full term normal healthy neonates and 18 intrauterine growth retarded (IUGR) neonates by the polymorphonuclear leucocyte overlay method (requiring only a few drops of blood). Cord IgG and IgM levels were determined by single radial immunodiffusion. Serum opsonic activity against Staph. aureus was significantly lower in the IUGR neonates (49.1 +/- 0.89), as compared to that in normal neonates (61.96 +/- 0.73; P less than 0.001). Immunoglobulin supplementation in vitro at a concentration of 5 g/dl significantly enhanced the opsonic activity of IUGR neonate sera. Cord IgG levels of IUGR neonates were significantly lower (P less than 0.01) than IgG levels of normal neonates. No significant difference was observed in cord IgM levels between the normal and IUGR neonates.