Your autoclave ran a clean cycle this morning. The chamber reached temperature, the chemical indicator changed colour, and the tape stripes look right. None of that proves the load is sterile. Chemical indicators confirm that the right conditions were present; only a biological indicator (BI) proves the spores were actually killed. In Ontario, that difference decides how often the test is run — and how an inspector reads your log.
In Ontario, the RCDSO requires a biological indicator for each sterilizer on every day it is used — daily monitoring, not weekly. The weekly baseline is the CDC and AAMI ST79 standard applied in most US states, so clinics that copy monitoring schedules from American sources often end up testing far less often than Ontario expects. Provincial regulators outside Ontario set their own monitoring expectations, and the CSA Z314 series covers reprocessing practice across Canadian healthcare settings. Whatever schedule applies to you, the record is what gets checked: dated results, a sterilizer identifier, and a control result beside each test.
What a self-contained biological indicator does
A self-contained biological indicator (SCBI) is a small vial. Inside is a strip inoculated with Geobacillus stearothermophilus (ATCC 7953) spores — the organism a steam sterilizer struggles with most — plus growth medium and a colour-change indicator. Crush the vial after the cycle, incubate it, and read the result. No media prep, no lab transfer, no guesswork.
Manufacturers performance-test these indicators against ISO 11138-3, the standard that sets spore population, D-value, and survival or kill requirements for moist-heat biological indicators. A compliant lot behaves predictably, and that is what makes a pass or fail meaningful.
The CliniEco 24-hour rapid readout biological indicator is built for the daily rhythm: place it in the load, run the cycle, activate the vial, and read a definitive answer the next morning. A 25-pack at $59.99 covers 25 testing days on a single sterilizer.
The daily protocol, step by step
Step 1: Run the BI before the first load
Place the indicator where steam arrives last: the front bottom tray of a fully loaded chamber, or the densest part of the load. That is the hardest spot to sterilize, so if the spores die there, they died everywhere in the load. Testing before the first load also means the result you read tomorrow describes the cycle you just validated, not a load that has already reached a patient.
Step 2: Run a normal cycle
Run the sterilizer exactly as you would for a real load. Do not change time, temperature, or packaging to favour the test. You are verifying the cycle you actually use on patients.
Step 3: Activate and incubate
After the cycle, remove the vial, let it cool, and crush the ampoule to release the growth medium. Incubate at 55–60°C for the time the manufacturer specifies. With the CliniEco rapid readout BI, a 24-hour readout means today's test gives tomorrow's answer.
Step 4: Read and record every result
A negative result — the medium keeps its original colour — means the spores were killed. A positive result, a colour change to yellow, means the cycle failed. Log every test: date, sterilizer number, cycle parameters, result, and the initials of the person who ran it. Keep the record for as long as your college or provincial regulator requires, and keep it where an inspector can reach it without asking you to search.
Step 5: Respond to a positive result
A positive BI is a signal, not a crisis. Quarantine the suspect load and hold those instruments until a retest is negative. Check the door seal, the drain screen, and how the load was packed. Run a fresh BI and confirm two consecutive negative results before returning the sterilizer to service.
Why a mail-in spore service slows the loop
Some clinics use a mail-in service instead of an in-office SCBI. It works, but it has a built-in delay: the strip is mailed out, cultured at the lab, and the result comes back days later. Under a daily monitoring schedule that delay compounds, and if a cycle failed, those instruments may already have been used on patients. An in-office 24-hour indicator closes the loop before the instruments reach the operatory.
BIs and chemical indicators: complementary, not interchangeable
Chemical indicators — tape, Class 4 pouch indicators, internal strips — confirm the load was exposed to heat and steam. They are fast and they catch gross errors such as a cold chamber. They do not prove lethality. Only a biological indicator demonstrates that the resistant organisms were destroyed. Use both on their own schedules: autoclave tape and Class 4 dual-indicator pouches on every pack, and a biological indicator in every sterilizer each day it is used.
Daily spore testing checklist
- Run one biological indicator per sterilizer on every day that sterilizer is used (RCDSO, Ontario).
- Place the indicator in the front bottom tray or the densest part of the load.
- Run a full, normal cycle with a realistic load configuration.
- Activate the vial, incubate at 55–60°C, and read at 24 hours.
- Record the result, cycle data, sterilizer ID, and technician initials.
- Keep the log accessible for inspectors and review it monthly.
- Quarantine and retest after any positive result before further use.
Daily spore testing is a small, repeatable habit that protects your patients, your licence, and your team's confidence. Build it into the opening routine, follow the checklist, and let the biological indicator do its work. Keep sterilization monitoring supplies on hand so the routine never waits on an order.
Frequently Asked Questions
How often should dental autoclaves be spore tested in Canada?
In Ontario, the RCDSO requires a biological indicator for each sterilizer on every day it is used. The weekly baseline — at least one test per sterilizer per week — is the CDC and AAMI ST79 expectation in most US states, and provincial regulators outside Ontario may follow their own schedules. Clinics with several sterilizers test each machine each day it runs and record the result every time.
What is a self-contained biological indicator?
A self-contained biological indicator (SCBI) is a small vial containing a strip inoculated with Geobacillus stearothermophilus (ATCC 7953) spores — the most heat-resistant organism a steam sterilizer faces — plus growth medium and a colour-change indicator, manufactured and tested to ISO 11138-3. After the cycle you crush the vial to release the medium, incubate it, and read the result. No media prep, no lab transfer.
Where should the biological indicator be placed in the autoclave?
Place the indicator in the worst-case location: the front bottom tray of a fully loaded chamber, or the densest part of the load. Steam arrives there last, so it is the hardest spot to sterilize. If the spores die there, they died everywhere in the load.
What temperature do you incubate a biological indicator at?
Incubate at 55 to 60°C for the time the manufacturer specifies. A 24-hour rapid readout indicator incubated at that range gives a definitive answer the next morning — a negative result means the medium keeps its original colour, and a positive result shows a colour change to yellow.
What happens if a spore test comes back positive?
A positive biological indicator is a signal, not a crisis. Quarantine the suspect load and hold those instruments until a retest is negative. Check the door seal, drain screen, and how the load was packed, then run a fresh indicator and confirm two consecutive negative results before returning the sterilizer to service. Record every result in a dated log.
Is a mail-in spore test as reliable as an in-office biological indicator?
A mail-in service works, but it has a built-in delay: the strip is mailed out, cultured at the lab, and the result comes back days later. Under a daily monitoring schedule that delay is expensive, because a failed cycle could have released instruments before anyone saw the result. An in-office 24-hour indicator catches a problem before instruments reach the operatory, which is why many Ontario clinics keep testing in-house.
How often do you need to do a spore test in an Ontario dental office?
Every day the sterilizer is used. The RCDSO Infection Prevention and Control standard requires a biological indicator to be placed in a process challenge device and used to test the sterilizer on each day it is operated, and for each type of cycle used. Weekly testing is the US CDC / AAMI ST79 baseline, not the Ontario requirement.
What counts as a spore test for RCDSO purposes?
A biological indicator (BI) containing Geobacillus stearothermophilus spores, processed inside a process challenge device (PCD) in a normally loaded cycle, then incubated and read. A chemical indicator or autoclave tape is not a spore test and does not satisfy the requirement.
How many biological indicators does a dental office need per year?
Plan on one per sterilizer per day it is used — roughly 250 per sterilizer per year on a five-day week across fifty working weeks — plus additional indicators for each different cycle type you run.
Canada Spore Test
A spore test in Canada means the same test everywhere: a biological indicator processed inside a process challenge device in a normally loaded cycle, incubated and read on a schedule set by your provincial regulator or accreditation body. Ontario dental clinics test every day the sterilizer runs. Other provinces and care settings follow their own schedules, and the CSA Z314 series is the Canadian technical reference behind much of that guidance. Mail-in monitoring is permitted, but an in-office dry-block incubator shortens the gap between a failed cycle and a recall to 24 hours.
Last updated: September 2026
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