In vitro adherence and accumulation of Staphylococcus epidermidis RP 62 A and Staphylococcus epidermidis M7 on four different bone cements

Bacterial resistance of Staphylococcus epidermidis, a serious pathogen of i mplant-related infections, to antibiotics is related to the production of a glycocalyx slime that impairs antibiotic access and the killing by host de fense mechanisms. In vitro studies of different bone cements containing ant ibiotics, developed for the prevention of biomaterial-associated infection, could not always demonstrate complete eradication of biomaterial-adherent bacteria. We have investigated four different bone cements in regard to bac terial accumulation of a slime-producing strain RP 62 A and its isogenic mu tant M7 lacking the ability to produce exopolysaccharide slime using a bact erial adhesion assay and modified Kirby-Bauer technique. A significant effe ct of exopolysaccharide production for the accumulation on bone cement coul d be demonstrated. The gentamicin/clindamycin bone cement was the only test ed biomaterial that produced a large zone of bacterial inhibition in the in oculated area adjacent to the biomaterial. The bacterial adhesion was not r educed significantly and there was no correlation between zones of inhibiti on on blood agar plates and the quantitative adhesion assay. The clinical e fficacy of the gentamicin/clindamycin bone cement must be proven in vivo.