Estudo da esterilização por plasma de acoplamento indutivo e análise comparativa com esterilização por óxido de etileno / Study of sterilization by Inductively coupled plasma and comparison with sterilization by ethilene oxyde

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The gas Plasma sterilization technology has been emerging as an alternative to conventional low temperature processes since the advent of new therapies using heat sensitive materials in the healthcare field is greater than ever. The gas Plasma mechanism of action includes the generation of actives species by an electrical discharge, which is able to promote lethal effect on microorganisms. The sterilization techniques using gas plasma are under intense investigation and it has already been demonstrated by recent studies that this technology is simple, cost-effective, suitable for microbicidal activity and absent of toxic residuals. Ethylene oxide is the sterilization agent most widely applied to medical devices. However, its explosiveness, inflammability and toxicity led to the search for other sterilization methods at low temperature and it has been used associated to non active gases which inhibit these properties and it is necessary to have the control at the occupational safety and environmental monitoration. Therefore, the aim of this work was to explore possible microbicidal application of the gas plasma sterilization generated by an inductively coupled system and to compare this sterilization method with ethylene oxide (chemistry substance in gaseous form), observing their D value. It was used distinct combinations of process parameters to sterilization by plasma, as follows: radio-frequency powers (300, 350 and 400 watts), exposition times (in the range of 3 to 60 minutes), gas (pure oxygen and mixture with hydrogen peroxide 5,10 and 20%), gas flow (100 sccm), pressure (330 mTorr), temperature (close to the environmental one) and relative humidity 80±5%. For ethylene oxide, Oxyfume 2002® was used (mixture of ethylene oxide, HCFCs 22 and 124), under the concentration of 450mg/L, at the temperature of 55°C and relative humidity of 50±5% and it was submitted to a time of exposition between 3 to 15 minutes. Both processes were submitted to exposition cycles in triple. Bacillus subtilis var. niger ATCC 9372 inoculated in a standard load of 107 spores per carrier was used as biological indicator. After the exposition, the biological indicators spore survivors were counted by the "Pour Plate" technique (incubation temperature of 35 ± 2ºC for 24 hours). Significant microbial reduction was observed in some cases where the plasma D value was between 3 and 8 min and 3,08 min, 3,04 min. to 350 and 400W powers respectively. In the ethylene oxide process the D value was 2,80 min. These results evidenced the higher effectiveness of ethylene oxide comparatively to plasma. However the latter presents advantages that make it an interesting alternative to low temperature sterilization processes.

ASSUNTO(S)

ethylene oxide bacillus subtilis Óxido de etileno plasma sterilization peróxido de hidrogênio plasma plasma esterilização por plasma bacillus subtilis hydrogen peroxide

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