Staphylococcus aureus biofilm formation on different gentamicin-loaded polymethylmethacrylate bone cements

Area of Science:

• Biomaterials Science
• Infectious Disease Research
• Orthopedic Surgery

Background:

• Bone cements are widely used in orthopedic surgery.
• Antibiotic-eluting bone cements aim to prevent surgical site infections, particularly those caused by Staphylococcus aureus.
• The efficacy of gentamicin-loaded bone cements against biofilm formation requires further investigation.

Purpose of the Study:

• To evaluate Staphylococcus aureus biofilm formation on six different gentamicin-loaded bone cements.
• To correlate biofilm formation with the known gentamicin release kinetics of these cements.
• To determine the effectiveness of gentamicin-loaded bone cements in inhibiting S. aureus biofilm development.

Main Methods:

• An in vitro study using a modified Robbins device over 3 days.
• Quantification of Staphylococcus aureus biofilm formation by colony-forming units (CFUs) per unit cement area.
• Comparison of CFU counts on gentamicin-loaded cements versus unloaded cements of the same brand.
• Correlation of biofilm data with previously published gentamicin release kinetics.

Main Results:

• Biofilms formed on all tested gentamicin-loaded bone cements, irrespective of antibiotic release.
• Maximum biofilm formation occurred between 24 and 30 hours post-inoculation.
• Only CMW1 and Palacos showed reduced biofilm formation at 24 hours.
• CMW Endurance, CMW2000, and Palamed exhibited delayed reductions (48-72 hours).
• CMW3 demonstrated the longest duration of biofilm reduction (24-72 hours).
• No direct relationship was found between gentamicin release kinetics and the 'window-of-effectiveness' for biofilm reduction.

Conclusions:

• Gentamicin-loaded bone cements can reduce Staphylococcus aureus biofilm formation.
• The timing and duration of biofilm reduction vary significantly among different bone cement brands.
• Staphylococcus aureus is capable of growing on gentamicin-loaded bone cements, indicating potential limitations in infection prevention.
• The release kinetics of gentamicin do not reliably predict the cement's ability to inhibit biofilm formation.