Tissue reactions to lead samples in a late infection rat model

Tissue reactions to rat lead samples, model ii ng for clinically used leads, were investigated in a late infection model, in which injection of bacteria was performed after a 3-week encapsulation process. At the site of injection, detachment of the original fibrous capsule, wound fluid infiltration, fibrin formation and granulocyte and macrophage infiltrations, occurred. Spreading of infection did not occur via the generally assumed direct bacterial adhesion to materials, but through blood vessels at the outside of capsules and through wound fluid passage at the interface a nd in the lumen of the lead sam pie. At day 5, infection had spread a II over, but, a pa rt from two sma II abscesses, seemed to be suppressed at day 10. However, probably due to iu mina I bacterial growth, at weeks 3 and 6 the reaction intensified showing larger abscesses with accumulations of lymphocytes. The results of this study represent a good basis for further studies aimed at developing infection-resistent lead material. Research efforts are first directed on modification of material surfaces to provide controlled release of antimicrobial agents.