Assessment of biological indicators in the validation of isolator decontamination with hydrogen peroxide

Abstract

Isolators allow decontamination gases to be employed to create a sterile processing environment. This feature, added to the potential removal of human interference in the process, makes the use of isolators rather advantageous, compared to performing aseptic processes in conventional clean rooms. Decontamination with vaporized hydrogen peroxide (VHP) offers several advantages over other available methods, as it decomposes to water and oxygen and is thus easy to remove after use, is highly compatible with materials usually employed in production areas and it is relatively cheap. The aims of this study were to prove that Geobacillus stearothermophilus (ATCC 12980) is more resistant than microorganisms isolated from the normal production area flora and to determine the best material to serve as a support during validation of the decontamination of the inner surfaces of isolators and outer surfaces of materials inside them. Bacillus sp., Micrococcus luteus, Corynebacterium, Staphylococcus sp. and Penicillium sp. were the microorganisms of highest incidence among those identified in the production area. Stainless steel is the best material to be used as a support for the VHP treatment of specimens, as it is inert and the main component of isolators and showed no incompatibility with this sterilizing agent. The results obtained in this phase of the experiment proved that Geobacillus stearothermophilus is the most resistant microorganism with which to challenge the effectiveness of hydrogen peroxide, when tested against species of the normal flora. Secondly, the best support material is stainless steel, showing that the commercial bioindicators available on the market with this support material are scientifically proved to be the best choice for this purpose.