Biological indicators for the control of the ethylene oxide sterilisation process

Biological indicators for ethylene oxide sterilisation are designed for monitoring the effectiveness of EO sterilisation processes. They contain a specific population of spores Bacillus atrophaeus deposited on a paper strip placed inside a plastic vial.

The vial also contains a glass ampoule holding culture medium. After the sterilisation and indicator activation process is complete, the ampoule is incubated under appropriate conditions and the result is assessed based on the colour change of the medium.

Biological indicators for ethylene oxide sterilisation – mechanism of action

Disputes Bacillus atrophaeus present a biological challenge to the ethylene oxide sterilisation process. Following exposure, the indicator must be activated and incubated in accordance with the manufacturer's instructions.

If microbial growth occurs during incubation, the culture medium will change colour to yellow. This is a positive result, indicating spore survival. If the spores have been inactivated, the colour of the culture medium will remain unchanged.

Incubation of EO biological indicators

The indicators must be incubated at a temperature of 37°C ±2°C for a period not exceeding 48 hours. According to the information on the product datasheet, the result should be checked every 12 hours.

The conditions for activation, incubation and interpretation of the result must be verified each time in the manufacturer's current instructions for use. An appropriate control indicator not subjected to exposure to the sterilisation cycle should also be used during the process control.

Chemical process indicator on the label

Each vial features an external label with a chemical exposure indicator. Upon exposure to the process, its colour changes from light blue to dark.

The colour change of the chemical indicator confirms exposure of the vial to the process, but does not confirm the biological efficacy of the sterilisation. The final result of the biological control is determined after properly conducted incubation.

Product identification and certificate

The packaging contains a certificate with information regarding, among other things:

• serial number,
• expiry date,
• spore population,
• resistances of the microorganisms used,
• resistance parameters determined in the BIER chamber.

These data enable batch identification and the proper documentation of the sterilisation process control.

Key information about indicators 2233AB

• destined for ethylene oxide EO sterilisation,
• disputes Bacillus atrophaeus,
• ampoule culture system,
• incubation at 37°C ±2°C,
• maximum incubation period 48 hours,
• result check every 12 hours,
• external chemical exposure indicator,
• product code: 2233AB,
• packaging: 100 pieces.

Indicators must be used, activated, incubated and interpreted in accordance with the manufacturer's current instructions and the approved procedure for monitoring the sterilisation process within the facility.