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Laboratory Research
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Microbiological evaluation of the bioburden and preservative efficacy of two moist wound dressing formulations, containing both a reduced pH and low chlorides E.R. Gubish, BioDerm Sciences, Inc. Oxford, MS; J. Tsioras,T. Riesinger T, NAWA Heilmittel GmbH, Nuremberg, Germany.. The purpose of these studies was to determine the effect of low pH containing wound management products to effect the growth of various microbiological agents. Two formulations were tested, an aqueous solution and a topical cream. The solution was preservative free and the cream contained a preservative. Both formulations contained low amounts of Zinc Chloride, Iron Chloride, Manganese Chloride, Copper Chloride, Chromium Chloride, Sodium Fluoride, Cobalt Chloride, Molybdenum Chloride, Potassium Iodide, Sodium Selenite and were prepared at pH <3.5. The test methodology was validated according to Microbiological Examination of non-sterile Products (USP 28 <61>). Assays were conducted to determine the ability of organisms to contaminate these formulations (bioburden) and the ability of organisms to sustain growth (preservative efficacy). Microorganisms were selected to include aerobic bacteria, spore-formers, yeast, fungi and normal flora that might be expected to infiltrate and infect a wound site. Newly prepared, as well as formulations held for three years were tested. Final testing was conducted according to USP 28<51>. Formulations were inoculated with test organisms and incubated. Colony counts were conducted out to 28 days post incubation. Results indicate that both formulations, with and without preservatives were bacteriostatic and in some cases bactericidal. Further, the aqueous solution also demonstrated no cytotoxic effects when incubated with L929 fibroblasts for a period up to 72h. We conclude that these wound management formulations have a selective anti-microbial effect with no mammalian cell toxicity and in the case of the aqueous solution do so in the absence of any preservative or silver. |
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