Incorporation of large amounts of gentamicin sulphate into acrylic bone cement: effect on handling and mechanical properties, antibiotic release, and biofilm formation

• Published in: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine Vol. 222; no. 3; p. 355
• Main Authors: Dunne, N J, Hill, J, McAfee, P, Kirkpatrick, R, Patrick, S, Tunney, M
• Format: Journal Article
• Language: English
• Published: England 01-03-2008
• Subjects: Anti-Bacterial Agents - administration & dosage; Anti-Bacterial Agents - therapeutic use; Biocompatible Materials - chemistry; Biocompatible Materials - therapeutic use; Biofilms - drug effects; Biofilms - growth & development; Bone Cements - chemistry; Bone Cements - therapeutic use; Compressive Strength; Drug Delivery Systems - methods; Drug Resistance, Bacterial; Elasticity; Gentamicins - administration & dosage; Gentamicins - chemistry; Gentamicins - pharmacokinetics; Gentamicins - therapeutic use; Hip Prosthesis - microbiology; Humans; Materials Testing; Polymethyl Methacrylate - chemistry; Prosthesis-Related Infections - drug therapy; Prosthesis-Related Infections - prevention & control; Staphylococcal Infections - drug therapy; Staphylococcal Infections - prevention & control; Staphylococcus - drug effects; Staphylococcus - growth & development; Tensile Strength; Treatment Failure
• ISSN: 0954-4119
• DOI: 10.1243/09544119JEIM355

Bacterial infection remains a significant complication following total joint replacement. If infection is suspected when revision surgery is being performed, a large dose of antibiotic, usually gentamicin sulphate, is often blended with the acrylic bone cement powder in an attempt to reduce the risk of recurrent infection. In this in-vitro study the effect of small and large doses of gentamicin sulphate on the handling and mechanical properties of the cement, gentamicin release from the cement, and in-vitro biofilm formation by clinical Staphylococcus spp. isolates on the cement was determined. An increase in gentamicin loading of 1, 2, 3, or 4 g, in a cement powder mass of 40 g, resulted in a significant decrease in the compressive and four-point bending strength, but a significant increase in the amount of gentamicin released over a 72h period. When overt infection was modelled, using Staphylococcus spp. clinical isolates at an inoculum of 1 x 10(7) colony-forming units/ml, an increase in the amount of gentamicin (1, 2, 3, or 4 g) added to 40 g of poly(methyl methacrylate) cement resulted in an initial decrease in bacterial colonization but this beneficial effect was no longer apparent by 72 h, with the bacterial strains forming biofilms on the cements despite the release of high levels of gentamicin. The findings suggest that orthopaedic surgeons should carefully consider the clinical consequences of blending large doses (1 g or more per 40 g of poly(methyl methacrylate)) of gentamicin into Palacos R bone cement for use in revision surgery as the increased gentamicin loading does not prevent bacterial biofilm formation and the effect on the mechanical properties could be important to the longevity of the prosthetic joint.