Comparison of ion plasma, vaporized hydrogen peroxide, and 100% ethylene oxide sterilizers to the 12/88 ethylene oxide gas sterilizer.
OBJECTIVE
The performance of a standard gas sterilizer, which uses a mixture of 12% ethylene oxide (EtO) and 88% chlorofluorocarbon as the sterilizing gas (12/88), was compared to selected gas, ion plasma, and vaporized hydrogen peroxide (H2O2) sterilizers that do not use chlorofluorocarbons. The effect of serum and salt on sterilizer performance was evaluated.


METHODS
Test carriers (porcelain and stainless steel penicylinders, or 125-cm lengths of plastic tubing [internal diameter of 3.2 mm]) were inoculated with Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Mycobacterium chelonei, Bacillus stearothermophilus spores, Bacillus subtilis spores, and Bacillus circulans spores and then subjected to sterilization using 12/88, 100% EtO, ion plasma, or vaporized H2O2. The bacterial inoculum was prepared with and without 10% serum and 0.65% salt, and the residual bacterial load after sterilization as determined using viable counts.


RESULTS
All of the sterilizers tested effected a six-log10 reduction of the bacterial inoculum on penicylinders, unless 10% serum and 0.65% salt were present, in which case the 100% EtO, vaporized H2O2, and ion plasma sterilizers were not as effective as the 12/88 sterilizer. None of the sterilizers could eradicate 10(6) CFU of all of the bacteria in 10% serum and 0.65% salt when inoculated inside a narrow lumen.


CONCLUSIONS
The margin of safety for the 100% EtO, vaporized H2O2, and ion plasma sterilizers is less than that of the 12/88 sterilizer. The inability of all sterilizers, including the 12/88, to kill organisms in narrow lumens reliably when serum and salt were present raises concern about the current practice of gas sterilization of flexible endoscopes.
Alfa
M J
MJ
St. Boniface General Hospital, Winnipeg, Manitoba, Canada.
DeGagne
P
P
Olson
N
N
Puchalski
T
T
D000704:Analysis of Variance; D017402:Chlorofluorocarbons; D015169:Colony Count, Microbial; D004724:Endoscopy; D005027:Ethylene Oxide; D005740:Gases; D006861:Hydrogen Peroxide; D013242:Sterilization / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D013673:Technology Assessment, Biomedical / Q000379:methods; D013696:Temperature; D014835:Volatilization
D017402:Chlorofluorocarbons; D005740:Gases; D006861:Hydrogen Peroxide; D005027:Ethylene Oxide