Thursday, April 12, 2018

Biological Indicators: Testing a Cycle's Success


ClorDiSys uses Biological Indicators (BIs) to verify the efficacy of our decontamination cycles. Also known as spore strips, the BIs we use consist of over a million (1 x 106Geobacillus stearothermophilus spores inoculated on a paper substrate and wrapped in Tyvek. The chlorine dioxide gas molecule is small enough to permeate the Tyvek and kill the spores inside. To challenge the decontamination/sterilization cycle, BIs are placed in hard to reach areas throughout the space being decontaminated. Once the decontamination has been completed, the BIs are dropped into growth media using aseptic technique. If the biological indicator does not produce growth within the media tube after the incubation period (we have validated a 36 hour incubation time with the BI manufacturer Crosstex), the process is deemed to be successful.

Below are some of the more challenging locations where Biological Indicators have been placed during chlorine dioxide gas decontaminations. All of these locations’ BIs exhibited 6-log sterilization level kill using our standard cycle.

Inside Packed Isolators
(Over 30 BIs were placed inside)

In Stacks of Filtered Cage Lids
(Blue tape on right corresponds to BIs shown in left image)

Underneath Dust
(Comparable to that of HEPA filters)

In HEPA Filters
(BI between the filter's pleats)

In Packed Storage Rooms
(BI placed at the bottom of the closest trash can)

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