Effects of loading concentration, blood and synovial fluid on antibiotic release and anti-biofilm activity of bone cement beads

Abstract

Antibiotic loaded cement beads are commonly used for the treatment of biofilm related orthopaedic periprosthetic infections; however the effects of antibiotic loading and exposure of beads to body fluids on release kinetics are unclear. The purpose of this study was to determine the effects of (i) antibiotic loading density (ii) loading amount (iii) material type and (iv) exposure to body fluids (blood or synovial fluid) on release kinetics and efficacy of antibiotics against planktonic and lawn biofilm bacteria. Short-term release into an agar gel was evaluated using a fluorescent tracer (fluorescein) incorporated in the carrier materials calcium sulfate (CaSO) and poly methyl methacrylate (PMMA). Different fluorescein concentrations in CaSO beads were evaluated. Mechanical properties of fluorescein-incorporated beads were analyzed. Efficacy of the antibiotics vancomycin (VAN) or tobramycin (TOB) alone and in combination was evaluated against lawn biofilms of bioluminescent strains of Staphylococcus aureus and Pseudomonas aeruginosa. Zones of inhibition of cultures (ZOI) were measured visually and using an in-vivo imaging system (IVIS). The influence of body fluids on release was assessed using CaSO beads that contained fluorescein or antibiotics and were pre-coated with human blood or synovial fluid. The spread from the beads followed a square root of time relationship in all cases. The loading concentration had no influence on short-term fluorescein release and pre-coating of beads with body fluids did not affect short-term release or antibacterial activity. Compared to PMMA, CaSO had a more rapid short term rate of elution and activity against planktonic and lawn biofilms. This study highlights the importance of considering antibiotic loading and packing density when investigating the clinical application of bone cements for infection management.

Antibiotic loaded calcium sulfate bead and pulse lavage eradicates biofilms on metal implant materials in vitro

“…Antibiotic loaded CS‐B are utilized as an augment to deliver locally high concentrations of antibiotics at periprosthetic infection sites. Previous studies have demonstrated the effectiveness of CS‐B as a carrier for antibiotics against a lawn of bacterial biofilm . Antibiotic loaded CS‐B reduced biofilms upto six log in the present study with a 24 h exposure period.…”

“…Bioluminescent strains of S. aureus (SAP231, a transformed USA 300 MRSA strain) and a P. aeruginosa PAO1 derivative (Xen 41, PerkinElmer, Waltham, MA) were used in this study, as previously described . S. aureus SAP231 was grown in Brain Heart Infusion broth (BHI; Sigma–Aldrich, St. Louis, MO) and P. aeruginosa Xen41 was grown in Lysogeny Broth (LB; Sigma–Aldrich) respectively at 37°C overnight on shaker conditions set at 200 rpm.…”

“…Prior to biofilm removal for cell count enumeration, bioluminescent imaging was performed using an IVIS 100 (Xenogen, Hopkinton, MA) on one representative coupon from each treatment and control group as previously described . IVIS provides a non‐destructive method of assessing the relative amount of actively growing biofilm .…”

Complete Killing of Agar Lawn Biofilms by Systematic Spacing of Antibiotic-Loaded Calcium Sulfate Beads

“…They release the full antibiotic load and achieve high levels of antibiotics locally over sustained periods, leaving no residual foreign body that could act as a nidus for biofilm formation. We have previously studied the killing of biofilms of bioluminescent strains of P. aeruginosa (PA-Xen41) and S. aureus (SA-SAP231) grown on agar surfaces by a combination of vancomycin and tobramycin impregnated calcium sulfate beads for three days [38]. In this present study, we extended the incubation period to determine whether we could achieve complete eradication of biofilm bacteria adjacent to the beads, including resistant phenotypes that develop in the presence of antibiotics.…”

A dual PMMA/calcium sulfate carrier of vancomycin is more effective than PMMA‐vancomycin at inhibiting Staphylococcus aureus growth in vitro

“…The main drawback of antibiotics‐loaded PMMA is the superfluous drugs at the initial releasing stage, which thus contributed to a deficient concentration for therapeutics at the later stage [5,6]. Due to the nonbiodegradable property of PMMA, the continuous reduction of antibiotics released by PMMA may result in proliferation of bacteria at the local sites and forming biofilms, which would be beneficial for the production of resistant bacteria and the recurrence of infection [7,8].…”