In vitro analysis of nonthermal plasma as a disinfecting agent.

OBJECTIVE: To determine the effect of nonthermal plasma on Staphylococcus aureus, fibroblasts in monolayer culture, and clean and contaminated skin explants. SAMPLE POPULATION: Normal skin from euthanized horses. PROCEDURES: S aureus organisms were plated and treated with nonthermal plasma followed by bacterial culture to assess viability. Fibroblasts in monolayer culture and the epidermal and dermal surfaces of clean and S aureus-contaminated skin explants were treated. The effects of distance and duration on the response to treatment were compared.
RESULTS: Compared with controls, treatment with nonthermal plasma resulted in significantly decreased bacterial growth and significantly inhibited survival of fibroblasts in monolayer culture. When epidermal and dermal surfaces of skin explants were treated, there was no effect on production of normal fibroblasts during explant culture, except when extended exposure times of >or= 2 minutes were used. Treatment with nonthermal plasma resulted in significantly lower bacterial counts after 24 hours of culture of S aureus-contaminated epidermis but not of dermis. CONCLUSIONS AND CLINICAL RELEVANCE: Nonthermal plasma resulted in bacterial decontamination of agar and epithelium; negative effects on fibroblasts in monolayer; and no negative effects on skin explants, except at long exposure times. Use of nonthermal plasma appears safe for treatment of epithelialized surfaces, may be safe for granulating wounds, and results in decontamination of S aureus. Investigations on the effects that nonthermal plasma may have on patient tissues are indicated with a clinically applicable delivery device.