Polymicrobial Biofilm Inhibition Effects of Acetate-Buffered Chitosan Sponge Delivery Device.

Polymicrobial biofilm-associated implant infections present a challenging clinical problem. Through modifications of lyophilized chitosan sponges, degradable drug delivery devices for antibiotic solution have been fabricated for prevention and treatment of contaminated musculoskeletal wounds. Elution of amikacin, vancomycin, or a combination of both follows a burst release pattern with vancomycin released above minimum inhibitory concentration for Staphylococcus aureus for 72 h and amikacin released above inhibitory concentrations for Pseudomonas aeruginosa for 3 h. Delivery of a vancomycin, amikacin, or a combination of both reduces biofilm formation on polytetrafluoroethylene catheters in an in vivo model of contamination. Release of dual antibiotics from sponges is more effective at preventing biofilm formation than single-loaded chitosan sponges. Treatment of pre-formed biofilm with high-dose antibiotic release from chitosan sponges shows minimal reduction after 48 h. These results demonstrate infection-preventive efficacy for antibiotic-loaded sponges, as well as the need for modifications in the development of advanced materials to enhance treatment efficacy in removing established biofilm.

Preliminary investigation of crosslinked chitosan sponges for tailorable drug delivery and infection control.

Local versus systemic antibiotic delivery may be an effective strategy for treating musculoskeletal infections, especially when antibiotic-resistant bacteria are present. Lyophilized uncrosslinked, genipin crosslinked, and genipin crosslinked with poly(N-isopropylacrylamide) (PNIPAM) chitosan sponges were analyzed for their in vitro degradation rate, chemical crosslinking, antibiotic uptake, elution, biologic activity, and cytotoxicity. These evaluations were pursued to determine if crosslinking with genipin could be used to create a tailorable point of care loaded sponge for local infection control. Crosslinking the chitosan sponges decreased degradation in phosphate-buffered saline from 4.48 ± 2.28 wt % remaining of the uncrosslinked sponges to 78.82 ± 1.15 and 73.87 ± 1.27 wt % remaining at week 1 for the genipin and PNIPAM/genipin crosslinked sponges, respectively. The PNIPAM/genipin crosslinked sponges exhibited the most sustained release of biologically active antibiotics, with an average antibiotic release 63% higher than uncrosslinked and 37% higher than genipin crosslinked sponges, after 96 h. No significant cytotoxic effects from sponges or eluates were exhibited with NIH 3T3 fibroblasts. These preliminary results indicate that genipin crosslinked chitosan sponges, with or without PNIPAM, have potential as local delivery systems for adjunctive therapy for infection control, especially when longer degradation periods and higher antibiotic elutions are desired.

Evaluation of two sources of calcium sulfate for a local drug delivery system: a pilot study.

BACKGROUND: Local drug delivery has substantial potential to prevent infections compared with systemic delivery. Although calcium sulfate (CaSO(4)) has been studied for local drug delivery and two types are commercially available, it is unknown whether they differentially release antibiotics. QUESTIONS/PURPOSES: We determined the differences between two sources of CaSO(4) and the K(2)SO(4) catalyst's presence on the degradation, daptomycin elution, and activity against Staphylococcus aureus. METHODS: We formed pellets from synthetic and naturally sourced (from gypsum) CaSO(4) and loaded with 5% daptomycin and 3% or 0% K(2)SO(4). We used in vitro experiments to determine the daptomycin concentration and degradation profiles over 10 days. Turbidity assays were used to evaluate the activity of the daptomycin eluates against S. aureus. RESULTS: All pellets exhibited a bolus release with the highest daptomycin concentration on Day 1 with the sourced CaSO(4) pellets. The synthetic CaSO(4) pellets with 3% K(2)SO(4) exhibited a slower drug release compared with the synthetic CaSO(4) pellets with 0% K(2)SO(4), which degraded and eluted daptomycin too quickly to inhibit S. aureus. Turbidity assays demonstrated that all CaSO(4) pellets inhibit S. aureus for expected lengths of time. CONCLUSIONS: Our preliminary in vitro data suggest differences in the degradation, elution, and activity properties between sourced and synthetic CaSO(4) pellets. The addition of K(2)SO(4) appeared beneficial when using synthetic CaSO(4). Synthetic CaSO(4) may be effective when slow degradation and longer elution times are needed. CLINICAL RELEVANCE: Local delivery of eluted daptomycin can be tailored through material selection and K(2)SO(4) addition.