ABSTRACTPhysical cold atmospheric surface microdischarge (SMD) plasma operating in ambient air has promising properties for the sterilization of sensitive medical devices where conventional methods are not applicable. Furthermore, SMD plasma could revolutionize the field of disinfection at health care facilities. The antimicrobial effects on Gram-negative and Gram-positive bacteria of clinical relevance, as well as the fungusCandida albicans, were tested. Thirty seconds of plasma treatment led to a 4 to 6 log10CFU reduction on agar plates.C. albicanswas the hardest to inactivate. The sterilizing effect on standard bioindicators (bacterial endospores) was evaluated on dry test specimens that were wrapped in Tyvek coupons. The experimentalD23°Cvalues forBacillus subtilis,Bacillus pumilus,Bacillus atrophaeus, andGeobacillus stearothermophiluswere determined as 0.3 min, 0.5 min, 0.6 min, and 0.9 min, respectively. These decimal reduction times (Dvalues) are distinctly lower thanDvalues obtained with other reference methods. Importantly, the high inactivation rate was independent of the material of the test specimen. Possible inactivation mechanisms for relevant microorganisms are briefly discussed, emphasizing the important role of neutral reactive plasma species and pointing to recent diagnostic methods that will contribute to a better understanding of the strong biocidal effect of SMD air plasma.
Cold Atmospheric Air Plasma Sterilization against Spores and Other Microorganisms of Clinical Interest
