ISO 14161 and EN ISO 11138: How Biological Indicator Standards Fit Together

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ISO 14161:2009 no longer exists as an active standard - it was withdrawn and replaced by ISO 11138-7:2019. That single fact invalidates a surprising number of clinic procedures, supplier documents and training decks that still instruct staff to follow ISO 14161 for the selection, use and interpretation of biological indicator results. This article maps the current biological indicator standard family part by part, explains the difference between an ISO and an EN ISO designation, and sets out which document answers which question so a procedure can be checked against the standards that are actually in force.

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Quick facts

  • ISO 14161:2009 is withdrawn. Its own replacement record states that it replaced ISO 14161:2000 and has been replaced by ISO 11138-7:2019, and the European adoption shows the same lifecycle: EN ISO 14161:2009 withdrawn, EN ISO 11138-7:2019 published.
  • The guidance function moved into the 11138 family. ISO 11138-7:2019 is titled "Guidance for the selection, use and interpretation of results" - the scope ISO 14161 used to hold. The American adoption is labelled a revision of ANSI/AAMI/ISO 14161:2009, which is why the two numbers appear together in older documents.
  • The 11138 parts are process-specific. Part 1 covers general requirements; Parts 2 to 5 cover ethylene oxide, moist heat, dry heat, and low-temperature steam and formaldehyde respectively; Part 8 covers validation of a reduced incubation time.
  • EN ISO and ISO designations carry the same technical content. EN ISO 11138-3:2017 is the European adoption of ISO 11138-3:2017, not a different requirement.
  • A seventh part for vaporized hydrogen peroxide is still in draft, so a clinic or facility using that process follows the process standard and the general indicator requirements rather than a published Part 6.

What replaced ISO 14161

ISO 14161:2009 held the guidance role for biological indicators - how to select one, how to use it, and how to interpret the result. Its lifecycle entry now reads as withdrawn, replaced by ISO 11138-7:2019, and the European standardisation record shows the same sequence: EN ISO 14161:2009 is listed as previously withdrawn, with EN ISO 11138-7:2019 published in its place.

The practical effect is narrow but real. Nothing about how a spore test is performed changes. What changes is the citation. A procedure that says "select and interpret biological indicators in accordance with ISO 14161" is pointing staff at a withdrawn document; the same procedure should cite ISO 11138-7:2019. The correction takes one line and removes a finding at the next audit.

The reason the two numbers travel together is the American adoption path: ANSI/AAMI/ISO 11138-7:2019 is published as a revision of ANSI/AAMI/ISO 14161:2009, so the predecessor number appears in the front matter of the current document. That is normal for a revised standard and is not evidence that ISO 14161 is still current.

Document Title Status
ISO 14161:2009 Biological indicators - Guidance for the selection, use and interpretation of results Withdrawn, replaced by ISO 11138-7:2019
ISO 11138-1:2017 Biological indicators - Part 1: General requirements Current (revision of ISO 11138-1:2006)
ISO 11138-2:2017 Biological indicators for ethylene oxide sterilization processes Current
ISO 11138-3:2017 Biological indicators for moist heat sterilization processes Current
ISO 11138-4:2017 Biological indicators for dry heat sterilization processes Current
ISO 11138-5:2017 Biological indicators for low-temperature steam and formaldehyde sterilization processes Current
ISO 11138-6 Biological indicators for vaporized hydrogen peroxide sterilization processes Draft, not published
ISO 11138-7:2019 Guidance for the selection, use and interpretation of results Current; replaces ISO 14161:2009
ISO 11138-8:2021 Method for validation of a reduced incubation time Current

How do the ISO 11138 parts fit together

The family is built as one general requirements document plus process-specific parts, with two further parts addressing guidance and a test method that would otherwise fall between the cracks.

Part 1:2017 is the backbone. It specifies general requirements for production, labelling, test methods and performance characteristics of biological indicators, including inoculated carriers and suspensions and their components, for use in validation and routine monitoring of sterilization processes. Its clause structure runs through general manufacturing requirements, specific manufacturing requirements, determination of population and resistance, and culture conditions, and its normative annexes cover viable count determination, growth inhibition by carriers and packaging materials exposed to sterilization processes, two D-value determination methods (survivor curve and fraction-negative), and survival-kill response characteristics.

Parts 2 to 5 attach the organism and the performance requirements to a process. A moist heat indicator is covered by Part 3, an ethylene oxide indicator by Part 2, and so on. An indicator purchased for one process should be documented against that process part; the general part alone does not state the process-specific performance requirement.

Part 7:2019 carries the guidance role. Selection, use and interpretation of results sit here, including how a result should be read in the context of the sterilization process being monitored.

Part 8:2021 covers a specific test method - establishing or confirming a reduced incubation time shorter than the seven-day reference incubation time specified in ISO 11138-1:2017. It exists because a shorter readout is a claim that has to be validated, and the validation method needed a home.

Question Document that answers it
How do I select, use and interpret a biological indicator result ISO 11138-7:2019
What are the general requirements for a biological indicator ISO 11138-1:2017
What performance requirements apply to a steam indicator ISO 11138-3:2017
What performance requirements apply to an ethylene oxide indicator ISO 11138-2:2017
How is a D-value determined ISO 11138-1:2017, Annex C (survivor curve) and Annex D (fraction-negative)
What is the survival time and kill time for a population ISO 11138-1:2017, Annex E
How is a shorter incubation time justified ISO 11138-8:2021
What does the sterilizer process itself have to meet ISO 17665:2024 for moist heat; ISO 11135 for ethylene oxide; ISO 14937 where no dedicated process standard exists

What is the difference between ISO 11138 and EN ISO 11138

Nothing technical. An EN ISO designation means the European standardisation body has adopted the international standard, so EN ISO 11138-3:2017 and ISO 11138-3:2017 carry the same technical content under two designations. Catalogue entries for both exist because each region lists its own adoption.

The distinction matters for two practical reasons. First, a certificate or technical data sheet may cite either designation, and a buyer comparing two suppliers' documents should not treat them as different requirements. Second, national adoptions such as ANSI/AAMI/ISO 11138-1:2017 exist for the same reason; they are the American adoption and are cited as such in manufacturer documentation. When a supplier's data sheet says an indicator meets ISO 11138-1:2017 and ISO 11138-3:2017, the substance is that the product is documented against the general requirements and the moist heat part.

Which process standard goes with which indicator standard

Indicator standards describe the test article. Process standards describe what the sterilizer and the cycle must achieve, and they are separate documents with separate scopes.

Technology Process standard Indicator standard
Moist heat (steam) ISO 17665:2024, which withdrew and replaced ISO 17665-1:2006 and consolidated the former Parts 2 and 3 technical specifications ISO 11138-3:2017
Ethylene oxide ISO 11135:2014 with Amendment 1 ISO 11138-2:2017
Dry heat Process requirements as applicable to the facility ISO 11138-4:2017
Low-temperature steam and formaldehyde Process requirements as applicable to the facility ISO 11138-5:2017
Vaporized hydrogen peroxide ISO 22441, with ISO 14937 available as the general process standard Part 6 is in draft; Part 1 general requirements apply
Sterilizing agents without a dedicated standard ISO 14937:2009 - general requirements for characterization of a sterilizing agent and for the development, validation and routine control of a sterilization process ISO 11138-1:2017

The most common pairing error in Canadian documents is citing ISO 17665-1:2006 as the current steam process standard. ISO 17665:2024 replaced it, and the 2024 edition is a single consolidated document rather than a part-numbered series.

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What should a clinic change in its procedures

Four citation checks catch almost every stale reference in a dental or clinic monitoring procedure.

  1. Replace ISO 14161 with ISO 11138-7:2019 wherever the procedure refers to selecting, using or interpreting biological indicator results.
  2. Replace ISO 17665-1:2006 with ISO 17665:2024 wherever a steam process standard is cited.
  3. Add the process-specific indicator part where a procedure cites only the general requirements - ISO 11138-3:2017 for steam, ISO 11138-2:2017 for ethylene oxide.
  4. Cite ISO 11138-8:2021 where a shorter readout is claimed, so that a fast readout is documented as a validated reduced incubation time rather than as a product feature.

None of these changes alters how often a sterilizer is monitored. Ontario's daily biological indicator requirement and the daily control test sit in provincial guidance and college standards, not in the ISO family; the standards define what the indicator is and how a result is interpreted, while the monitoring frequency comes from the regulator.

For a clinic that wants the indicator documentation to match the standards it cites, the straightforward route is an indicator whose instructions for use name the applicable parts. A 24-hour self-contained 25-pack covers about a month of daily monitoring for one sterilizer, a 3-hour fluorescence 50-pack suits dry-block workflows, a 5-pack trial is the smallest way to start, and the sterilization compliance hub collects the monitoring chain end to end.

Sources

Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers case pricing and account setup, and the B2B wholesale collection lists the lines stocked for institutional buyers.

Related reading

The process parts are broken down one by one in our ISO 11138 series guide covering Parts 1, 2, 3 and 4, and the same family mapped onto sterilizer types is in ISO 11138 series standards for steam, EO and hydrogen peroxide. The commercial question of whether one brand's indicator can be used with another brand's sterilizer is answered in locked into one BI brand? what ISO 11138-3 actually requires, and the frequency requirement set by the regulator rather than the standard is in when to run a biological indicator: the Ontario daily rule.

Related Reading

Frequently Asked Questions

Is ISO 14161 still valid

No. ISO 14161:2009 is withdrawn and has been replaced by ISO 11138-7:2019, which carries the guidance for selection, use and interpretation of biological indicator results. The European record shows EN ISO 14161:2009 as previously withdrawn with EN ISO 11138-7:2019 published in its place. A procedure citing ISO 14161 cites a withdrawn standard.

Why do ISO 14161 and ISO 11138-7 appear in the same document

Because the American adoption of ISO 11138-7:2019 is published as a revision of ANSI/AAMI/ISO 14161:2009. Revised standards commonly name their predecessor in the front matter, so the presence of the older number inside the current document is evidence of the lineage, not evidence that both are current.

What is the difference between ISO 11138 and EN ISO 11138

No technical difference. EN ISO designates the European adoption of the international standard, so EN ISO 11138-3:2017 and ISO 11138-3:2017 have the same technical content. National adoptions such as ANSI/AAMI/ISO 11138-1:2017 exist on the same basis, which is why a supplier data sheet may cite any of the three designations.

Which part of ISO 11138 applies to my steam sterilizer

The indicator is covered by ISO 11138-3:2017 for moist heat, in addition to the general requirements in ISO 11138-1:2017. The sterilizer and the cycle are covered by the process standard, ISO 17665:2024, which replaced ISO 17665-1:2006. The two documents have different scopes and a monitoring procedure should cite both where it addresses the test article and the process.

Is there an ISO 11138 part for vaporized hydrogen peroxide

Not yet published. Part 6, covering biological indicators for vaporized hydrogen peroxide sterilization, remains in draft, and the process requirements are addressed by ISO 22441 and by ISO 14937 as the general process standard. Until Part 6 publishes, an indicator for that process is documented against the general requirements in Part 1 plus the applicable process standard.

Where does ISO 11138-8 fit

Part 8:2021 specifies the test method used to establish or confirm a reduced incubation time shorter than the seven-day reference incubation time set in ISO 11138-1:2017. It is the document behind any claim that an indicator can be read in 24 hours or three hours, and it applies to indicators for moist heat and ethylene oxide sterilization.

Does the ISO family set monitoring frequency

No. The ISO 11138 family defines the indicator and how results are interpreted; the process standards define what the sterilization process must achieve. Monitoring frequency comes from the regulator and from provincial guidance - in Ontario, a biological indicator for each sterilizer on every day it is used, with a control test recorded at the same time.

CliniEco Medical distributes in Canada under MDEL #35334.

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