Inactivation of Gram-Negative Bacteria by Low-Pressure RF Remote Plasma Excited in N(2)-O(2) Mixture and SF(6) Gases

The role of low-pressure RF plasma in the inactivation of Escherichia coli O157, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter sakazakii using N(2)-O(2) and SF(6) gases was assessed. 1×10(9) colony-forming units (CFUs) of each bacterial isolate were placed on three polymer foils. The effects of pressure, power, distance from the source, and exposure time to plasma gases were optimized. The best conditions to inactivate the four bacteria were a 91%N(2)-9%O(2) mixture and a 30-minute exposure time. SF(6) gas was more efficient for all the tested isolates in as much as the treatment time was reduced to only three minutes. Therefore, low-pressure plasma could be used to sterilize heat and/or moisture-sensitive medical instruments.