Overview
EN ISO 11138-3:2017 (ISO 11138-3:2017) specifies requirements for biological indicators, inoculated carriers, suspensions, test organisms and test methods used to assess the performance of moist heat (steam) sterilization processes. Published by CEN and aligned with ISO, this part of the ISO 11138 series focuses on biological indicators intended for use with dry saturated steam (moist heat) and is intended for production, labelling, testing and performance declaration of those indicators.
Key topics and technical requirements
- Test organism: Spores of Geobacillus stearothermophilus are specified as the primary test organism; other strains with demonstrated equivalent performance are permitted. (The standard notes reclassification of Bacillus stearothermophilus to Geobacillus stearothermophilus and cites example strains.)
- Suspensions, inoculated carriers and biological indicators: Requirements cover production, packaging, labelling and the form in which spores are supplied for validation and monitoring.
- Carrier and primary packaging: Suitability must be demonstrated; defined exposure conditions are used to test carriers (e.g., exposure to dry saturated steam, minimum/maximum temperature criteria and a representative exposure time).
- Population and resistance:
- Manufacturers must state viable counts and resistance characteristics.
- Resistance is expressed as the D value at 121 °C (minutes) and reported to one decimal place.
- The standard requires determination of z value across at least three temperatures in the 110–138 °C range.
- The document sets minimum resistance criteria (e.g., a specified minimum D value at 121 °C) and defines test methods (Annex A) for resistance determination.
- Test methods and calculations: Normative annexes provide the method to determine moist-heat resistance and calculation of z value and statistical parameters.
Applications
- Validation and routine monitoring of steam autoclaves and other moist heat sterilization equipment.
- Supplier specification and quality control for manufacturers of biological indicators.
- Performance testing during sterilizer qualification, requalification and process change control.
- Reference guidance for test laboratories performing biological indicator characterization.
Who uses this standard
- Manufacturers of biological indicators and inoculated carriers
- Sterilizer and medical device manufacturers
- Sterilization validation and quality assurance engineers in healthcare and industry
- Test laboratories and regulatory bodies involved in sterilization conformity assessment
Related standards
- ISO 11138‑1:2017 - General requirements for biological indicators
- ISO 17665 series - Validation and routine control of moist heat sterilization processes
- ISO 14161 - Guidance on selection, use and interpretation of biological indicators
Keywords: EN ISO 11138-3:2017, ISO 11138-3:2017, biological indicators, moist heat sterilization, Geobacillus stearothermophilus, D value, z value, inoculated carriers, sterilization validation, dry saturated steam.
