Comparative sterilization effectiveness of plasma in O2-H2O2 mixtures and ethylene oxide treatment.
We investigated the influence of variable parameters of plasma sterilization and compared its effectiveness with that of ethylene oxide using a reactive ion etching plasma reactor at 13.56 MHz. Gases tested were pure oxygen and oxygen-hydrogen peroxide mixtures in 190/10, 180/20, and 160/40 sccm ratios with constant gas flow at 200 sccm, pressure at 0.100 torr, radio-frequency power at 25 W, 50 W, 100 W, and 150 W, and temperature below 60 degrees C. Ethylene oxide sterilization was performed using 450 mg/L at 55 degrees C, 60% humidity, and -0.65 and 0.60 kgf/cm2 pressure. The biological indicator was Bacillus atrophaeus ATCC 9372, with exposure times of 3 to 120 min. Observed D values were 215.91, 55.55, 9.19, and 2.98 min for pure oxygen plasma at 25 W, 50 W, 100 W, and 150 W, respectively. Oxygen-hydrogen peroxide plasma produced D values of 6.41 min (190/10), 6.47 min (180/20), and 4.02 min (160/40) at 100 W and 1.47 min (190/10), 3.11 min (180/20), and 1.94 min (160/40) at 150 W. Ethylene oxide processes resulted in a D value of 2.86 min. Scanning electron microscopy analyses showed damage to the spore cortex.
Silva
J M F
JM
Laboratory of Medicine and Cosmetic Quality Control, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil. jmfsilva@usp.br
Moreira
A J
AJ
Oliveira
D C
DC
Bonato
C B
CB
Mansano
R D
RD
Pinto
T J A
TJ
D004202:Disinfectants / Q000494:pharmacology*; D005027:Ethylene Oxide / Q000494:pharmacology*; D006801:Humans; D010949:Plasma / Q000737:chemistry* / Q000187:drug effects; D013242:Sterilization
D004202:Disinfectants; D005027:Ethylene Oxide