In vitro testing of gentamicin-vancomycin loaded bone cement to prevent prosthetic joint infection

Sepsis is a greatly feared complication of total joint arthroplasty. One key question is how to prevent perioperative bacterial adherence, and therefore the potential for infectious complications. The objective of our study was to appraise the emerging capacity of staphylococcal survival on prosthetic materials and to analyze the in vitro effects of gentamicin and vancomycin loaded polymethylmethacrylate (PMMA) cement on bacterial adherence and growth. Hospital acquired staphylococcal strains were systematically inoculated on four orthopedic materials (ultrahigh molecular weight polyethylene, PMMA without antibiotic, commercially produced PMMA loaded with gentamicin, and manually mixed PMMA loaded with gentamicin and vancomycin). Staphylococci were identified using culture and biochemical tests. The inoculated material was allowed to incubate in a liquid broth growth media and subsequently prepared for scanning electron microscopy and bacterial growth quantification. Materials without antibiotics showed evidence of staphylococcal growth. PMMA loaded with only gentamicin grew methicillin-resistant Staphylococcus aureus. Gentamicin-vancomycin loaded PMMA completely inhibited any bacterial growth. Low-dose gentamicin-vancomycin loaded PMMA prevents staphylococcal colonization better than commercially manufactured PMMA loaded with gentamicin. We recommend this combination in high-risk procedures and revision surgeries requiring bone cement.