The elution kinetics of antibiotics within each body cavity is an important factor in treating bacterial biofilm infections. It is important for the antibiotics to maintain or surpass the minimum inhibitory concentration (MIC) as bacterial biofilms require higher than MIC concentrations for an extended time to eradicate biofilm bacteria. Conventional laboratory elution kinetic studies use closed systems; however, these systems neglect to consider continuous fluid exchange which changes in the joint space as observed from clinically measured draining rates.
The aim of this present study was to develop a method to allow direct comparison of the antibiotic concentration profile when released from non-absorbable and absorbable depots in an artificial draining knee model including a PMMA spacer, STIMULAN
beads and bolus vancomycin powder. Tobramycin and Vancomycin concentrations were determined using LCMS. Zone of inhibition were used to confirm potency and the area under the curve (AUC) was used to compare applications.
The vancomycin powder initially demonstrated high concentrations in the effluent but was steadily and rapidly washed out so that after 2h it was below detection limits by LCMS. STIMULAN
+ PMMA spacer provided higher concentrations of antibiotic and a larger AUC at 24h and 48h than other methods assessed. This suggests that the combination of STIMULAN
+ PMMA may present an optimal combination for killing biofilm bacteria.
The abstract can be read, and the full paper can be obtained here.