Local antibiotic delivery using tailorable chitosan sponges: the future of infection control?

OBJECTIVES Local antibiotic delivery is a viable and attractive option for preventing infection. Unfortunately, the current options are limited and often necessitate surgical removal. This study evaluates the ability of a biodegradable and biocompatible chitosan sponge to minimize infection by delivering local antibiotics within the wound. METHODS A complex musculoskeletal wound was created on the hindlimb of goats and contaminated with Pseudomonas aeruginosa (lux) or Staphylococcus aureus (lux) bacteria. These bacteria are genetically engineered to emit photons, allowing for quantification with a photon-counting camera system. The wounds were closed and similarly débrided and irrigated with 9 L normal saline using bulb-syringe irrigation 6 hours after inoculation. Goats were assigned to different treatment groups: a control group with no adjunctive treatment and an experimental group using a chitosan sponge loaded with either amikacin (for wounds contaminated with P. aeruginosa) or vancomycin (for wounds contaminated with S. aureus). The wounds were closed after the procedure and evaluated 48 hours after initial contamination. Serum levels of the antibiotics were also measured at 6, 12, 24, 36, and 42 hours after treatment was initiated. RESULTS The wounds treated with the antibiotic-loaded chitosan sponge had significantly less bacteria than the untreated wounds (P < 0.05). The highest serum levels were 6 hours after treatment but remained less than 15% of target serum levels for systemic treatment. At study end point, all sponges were between 60% and 100% degraded. CONCLUSIONS The chitosan sponges are effective delivering the antibiotic and reducing the bacteria within the wounds.