Biological monitoring and spore testing for dental sterilizers in Ontario

The three types of sterilizer monitoring

A complete program uses three layers together, not just one. Mechanical monitoring checks the sterilizer's own readouts - time, temperature, and pressure - every cycle. Chemical monitoring uses indicators (the colour-change strips and pouch markings) to confirm a load was exposed to sterilizing conditions. Biological monitoring - the spore test - is the gold standard, because it uses live, highly resistant bacterial spores to prove the cycle actually kills microorganisms. Only the biological test confirms sterilization really happened.

• Mechanical: time, temperature, pressure readouts every cycle
• Chemical: indicator strips and pouch colour change on each package
• Biological (spore test): live spores that prove lethality

How often to run a spore test in Ontario

The RCDSO standard calls for biological monitoring at least once per week for each sterilizer, and Public Health Ontario guidance leads many Ontario clinics to test daily - the per-test cost is small next to the liability of an undetected sterilization failure. Beyond the routine interval, always run a biological test after any sterilizer repair, relocation, or malfunction, and with every load containing implantable devices (holding the load until you have a negative result). Whatever cadence you choose, write it into your protocol and run it the same way every time. For the surrounding water side of reprocessing, see our dental unit waterline guide.

• At least weekly per the RCDSO standard - daily is common in Ontario
• After every repair, relocation, or malfunction
• With every load containing implantable devices
• Include a control test with each biological indicator lot

What a control is - and why it matters

Each time you run a spore test, incubate a control indicator from the same lot that has not been through the sterilizer. The control should show growth (proving the spores were viable) while the processed indicator shows no growth (proving the cycle killed them). Without a control, a 'pass' doesn't actually prove anything - the spores could have been dead before the cycle even started.

What to do when a spore test fails

A failed biological test is a defined IPAC event, not a maintenance annoyance. Take the sterilizer out of service, quarantine and recall processed loads back to the last negative test where practical, investigate the cause (loading, cycle selection, or a mechanical fault), have the unit serviced if needed, and retest - ideally three consecutive negative biological tests - before returning it to use. Then document every step. A failure you caught and corrected demonstrates a working program; a failure with no record is a serious finding.

• Remove the sterilizer from service immediately
• Recall and re-process affected loads to the last negative test
• Investigate the cause and service the unit if needed
• Retest until you have consecutive negative results
• Document the failure and every corrective action

The records inspectors expect

Spore testing is only as good as its paper trail. Inspectors want to see your biological monitoring log, the test results (including controls), and documented corrective action for any failure - the same documentation discipline that runs through your whole IPAC program. Prime DMS builds sterilization monitoring into every IPAC compliance audit and writes the protocol and log templates into your clinic-specific IPAC manual, so the routine and the records always match.