Interaction of Staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes

This study focuses on the interaction of Staphylococcus epidermidis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p < or = 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.