title: Effect of gas composition on spore mortality and etching during low-pressure plasma sterilization.
abstract: The aim of this work was to investigate possible mechanisms of sterilization by low-temperature gas plasma: spore destruction by plasma is compared with etching of synthetic polymers. Bacillus subtilis spores were inoculated at the bottom of glass vials and subjected to different plasma gas compositions (O(2), O(2)/Ar, O(2)/H(2), CO(2), and O(2)/CF(4)), all known to etch polymers. O(2)/CF(4) plasma exhibited much higher efficacy than all other gases or gas mixtures tested, with a more than 5 log decrease in 7.5 min, compared with a 2 log decrease with pure oxygen. Examination by scanning electron microscopy showed that spores were significantly etched after 30 min of plasma exposure, but not completely. We speculate about their etch resistance compared with that of synthetic polymers on the basis of their morphology and complex coating structure. In contrast to so-called in-house plasma, sterilization by Sterrad(R) tended to increase the observed spores' size; chemical modification (oxidation), rather than etching, is believed to be the sterilization mechanism of Sterrad(R).
authors.affiliation: Research Group on Biomechanics and Biomaterials, Biomedical Engineering Institute, Ecole Polytechnique, Station Centre-Ville, P. O. Box 6079, Montreal, Quebec H3C 3A7, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Lerouge
authors.forename: M R
authors.initials: MR
authors.lastname: Wertheimer
authors.forename: R
authors.initials: R
authors.lastname: Marchand
authors.forename: M
authors.initials: M
authors.lastname: Tabrizian
authors.forename: L
authors.initials: L
authors.lastname: Yahia
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects* / Q000648:ultrastructure; D005027:Ethylene Oxide; D005466:Fluorocarbons; D005740:Gases; D006358:Hot Temperature; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D013171:Spores, Bacterial / Q000187:drug effects / Q000648:ultrastructure; D013242:Sterilization
chemical_list: D005466:Fluorocarbons; D005740:Gases; C035066:carbon tetrafluoride; D005027:Ethylene Oxide; D010100:Oxygen