Characteristics and clinical assessment of antibiotic delivery by chitosan sponge in the high-risk diabetic foot: a case series.

OBJECTIVE: The local delivery of antimicrobials is attractive for a number of reasons. Chitosan, a biodegradable polysaccharide sponge material, has been proposed as medium to deliver antibiotics directly to wounds. In this report we evaluate the safety and practicality of antimicrobial delivery via chitosan sponge. METHOD: We present the clinical course and systemic absorption characteristics of three cases of people with diabetic foot wounds treated with antibiotic soaked chitosan sponge (Sentrex BioSponge, Bionova Medical, Germantown, TN). The antibiotic sponge was made by reconstituting 1.2g tobramycin or 100mg doxycycline in 10-15ml saline and saturating the sponge with the solution. The sponge was then applied to the wounds. Serum levels of each respective antibiotic were evaluated after application. Additional in vitro studies were conducted evaluating elution of antibiotics from the chitosan sponge at established minimum inhibitory concentrations (MIC) for Staphylococcus aureus over 28 days. RESULTS: No patient experienced adverse local or systemic effects due to the sponge treatment. The measured serum levels applied antibiotics remained far less than established minimums after intravenous therapy. Each patient required further treatment, however local infection or contamination resolved during the course of their hospital stay after the chitosan/antibiotic application. CONCLUSION: The use of antibiotic-impregnated chitosan sponges appears a safe and effective mechanism of local delivery of antimicrobials in wounds. Future studies and clinical trials are ongoing to confirm these results and to guide clinical applications.

Effects of stocking rate, forage management, and grazing management on performance and economics of cow-calf production in Southwest Arkansas.

The objective this research was to determine the effect of application of multiple grazing management practices at 2 stocking rates (SR) on the productivity and economics of the cow-calf enterprise in the Southeastern United States over a 4-yr period. Pasture management systems included: continuous grazing management at a moderate SR (0.8 ha/cow; CG) without additional forage management, rotational grazing management at a moderate SR (0.8 ha/cow (MR) with addition of stockpiled bermudagrass [ (L.) Pers.] and complementary cool season annuals, and rotational grazing management similar to MR but with a high SR (0.4 ha/cow; HR). Stockpiling in MR and HR was managed by fertilization of 0.2 ha/cow of bermudagrass in early August with 168 kg ammonium nitrate and deferring grazing until November. Wheat (; 112 kg/ha) and annual ryegrass ( Lam.; 28 kg/ha) were interseeded (0.2 ha/cow) in HR and MR with a no-till drill in the fall. Cow and calf performance and economics data were analyzed by ANOVA using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC) and pregnancy percentage was analyzed using the GLIMMIX procedure of SAS; pasture was the experimental unit and year was the random block. Hay feeding days decreased ( < 0.01) from 107 ± 10.9 d for CG to 37 ± 10.9 d for HR, which was further reduced ( = 0.01) to 15 ± 10.9 d for MR. Pregnancy percentage did not differ ( = 0.20) among treatments. Weaning BW in CG (237 ± 7.3 kg) tended ( = 0.09) to be greater than in MR (227 ± 7.3 kg) and were greater ( < 0.01) than in HR (219 ± 7.3 kg). However, total weaning BW per hectare was 89% greater ( < 0.01) for HR compared with CG and MR, which did not differ ( = 0.31). With rotational stocking, there was the opportunity to harvest excess forage as hay in both MR and HR with a net value of US$52.90/ha ± 25.73 and $15.50/ha ± 25.73, respectively. Net returns per hectare did not differ ( = 0.30) between CG ($429 ± 63.0/ha) and MR ($479 ± 63.0/ha) but were increased ( < 0.01) by 107% by HR ($1,024 ± 63.0/ha). Using rotational grazing, stockpiled bermudagrass, and complementary cool-season annual grasses can drastically reduce winter feed requirements and simultaneously increase carrying capacity and net return.