Prolonged leaching time of peptide antibiotics from acrylic bone cement

The leaching time of antibiotics in growth inhibitory concentrations from p olyacrylic bone cements was determined using Escherichia coli, methicillin resistant Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pne umoniae, and Pseudomonas aeruginosa as target bacteria. The leaching time o f the peptide antibiotics vancomycin and polymyxin B nonapeptide was consid erably longer than that of gentamicin, novobiocin, and erythromycin, Among the nonpeptide antibiotics, the leaching time of novobiocin lasted longer t han did that of gentamicin, The acylated parent polymyxin B antibiotic leac hed for a considerably shorter period than did the deacylated polymyxin B n onapeptide derivative, suggesting that the lipids impede the leaching proce ss from the cement. Cement beads impregnated with polymyxin B nonapeptide a nd introduced into the tibia of three rabbits receiving oral novobiocin pro tected bone infection against a challenge of Pseudomonas aeruginosa that ot herwise caused infection in tibias containing gentamicin impregnated cement beads. The peptide antibiotics alone or in combination with other antibiot ics (polymyxin B nonapeptide and novobiocin) impregnated in cements for ort hopaedic procedures may provide longer periods of protection against a wide range of bacterial pathogens.