INVITRO STUDY ON THE INTEGRITY OF A HYDROXYLAPATITE COATING WHEN CHALLENGED WITH STAPHYLOCOCCI

An in vitro study was performed to evaluate the effect of Staphylococc us aureus and Staphylococcus epidermidis on the integrity of a hydroxy lapatite coating. The coating plasmasprayed on poly(L-lactide), showed dissolution during a 24 h incubation period. This was indicated by an increase in pH and calcium release in the buffer solution. After 4 h of incubation, calcium levels decreased due to the precipitation of ca lcium phosphate complexes on the coating. The bacteria digested or dis solved the coating, creating irregularly shaped holes. Although the in tegrity of the hydroxylapatite coating was focally damaged within 2-4 h of incubation with staphylococci, the extent of the damage was only marginal. Due to the formation of a layer of CaP precipitates though, bacteria could not be counted accurately after 4-8 h of incubation. Th is model could reveal part of the failure mechanism of infected hydrox ylapatite coated implants.