To determine whether all the spores in the indicator tube have been
killed during the sterilisation cycle they need to be exposed to growth
medium and incubated at 37°C for 48 hours. The growth medium is
contained in a glass vial within the indicator tube and the medium is
released onto the spore strip by bending the tube to crack the glass
vial. Incubation may be done in an incubation cabinet or using the
14 well incubator (AN-2205).
If the culture medium remains a
clear orange after 48 hours incubation then the sterilisation cycle was
successful. If the culture medium turns a milky yellow then indicator
contained live spores.
The tube also has a colour change indicator band to show when the indicator has been exposed to EtO.
used these self-contained biological indicators may be used for quality
assurance purposes to control the release of loads that have been
processed through an EtO sterilisation chamber. They are also
appropriate for use in validation studies and may form part of the
process challenge device (PCD).