The ISO 11138 series is the family of standards that defines how biological indicators for sterilization are manufactured, characterised and tested. It tells a buyer what a manufacturer had to prove before a spore strip, ampoule or self-contained indicator could claim a species and a population. For a Canadian clinic the value is procurement clarity: it separates an indicator that was verified against ISO 11138 from one that simply prints the word “spore” on the box.
When you buy a 24-hour biological indicator, the certificate of analysis should name the organism, the population and the D-value the manufacturer established, and those figures should be traceable to the relevant part of the series.
What does ISO 11138 cover, part by part?
The series is split so that general requirements sit in one part and product-specific requirements sit in others. Reading the table below is enough to know which document a certificate should reference.
| Part | What it covers | Typical product |
|---|---|---|
| ISO 11138-1 | General requirements for all biological indicators | Definitions, population and resistance |
| ISO 11138-2 | Indicators for ethylene oxide sterilization | EO spore strips |
| ISO 11138-3 | Indicators for moist heat sterilization | Steam spore ampoules and strips |
| ISO 11138-4 | Indicators for dry heat sterilization | Dry heat indicators |
| ISO 11138-5 | Indicators for low-temperature steam and formaldehyde | LTSF indicators |
Most dental and clinic sterilizers are steam units, so ISO 11138-3 is the part that matters day to day, with ISO 11138-1 supplying the general rules.
How does ISO 11138 differ from ISO 11140?
The two series are often confused because they both live under sterilization indicators. ISO 11138 covers biological indicators — the ones that contain live spores and prove lethality. ISO 11140 covers chemical indicators, the printed strips, dots and tape that change colour to show a load was exposed. A pouch with an external process indicator and an internal chemical indicator is an ISO 11140 product; the spore ampoule you incubate is an ISO 11138 product.
In practice a clinic needs both, and they answer different questions. Chemical indicators say the load saw the conditions; biological indicators say the cycle killed the challenge organism.
How do you verify a supplier actually meets ISO 11138?
Ask for three things. First, a certificate of analysis naming the test organism, for steam typically a Geobacillus stearothermophilus strain. Second, a stated spore population per carrier. Third, the D-value the manufacturer measured. If a supplier cannot produce those figures, the product may still work but you cannot audit it, and an inspector who asks for the traceability will not find it.
Colour change on the box is not evidence. Resistance data is.
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. Reselling? become a distributor.
Take the paperwork with you: download the printable sterilization log sheet, build a month of entries with the log generator, and ask a compliance specialist to review your records before an inspection.
Related reading
The spore behind sterilization testing · Indicator tape vs indicator test strips · Sterilization monitoring supplies
Frequently Asked Questions
What is ISO 11138?
The standard series that defines requirements for biological indicators, including the test organism, population and resistance data a manufacturer must establish.
Which part applies to steam sterilizers?
ISO 11138-3 covers indicators for moist heat sterilization, supported by the general requirements in ISO 11138-1.
Is ISO 11138 the same as ISO 11140?
No. ISO 11138 covers biological indicators containing live spores; ISO 11140 covers chemical indicators such as tape and printed strips.
What should a certificate of analysis include?
The test organism, the spore population per carrier and the measured D-value, traceable to the relevant part of the series.
CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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