Ensuring Sterilization Quality: The New Biological Indicator Service (Spore Test)
Cover Story
Every day, laboratories across campus rely on autoclaves to sterilize biological waste and equipment. We check the digital displays, monitor the pressure gauges, and check for visual changes on the indicator stripes on autoclave tape. But can we rely on these signs alone?
Physical parameters and chemical indicators (such as autoclave tape) only tell part of the story — while they confirm that the chamber has reached the required temperature and pressure, they cannot verify whether microorganisms have been completely destroyed.
To ensure sterilization effectiveness, HSO is now introducing a comprehensive Biological Indicator (BI) Spore Test Service.
Why Spore Testing Matters: The Ultimate Challenge
Autoclaves are subject to wear and tear over time — mechanical components degrade, heating elements weaken, and human error can occur. Regular performance verification is therefore essential to ensure consistent and reliable sterilization.
BI testing provides the most rigorous validation standard by using Geobacillus stearothermophilus spores. These thermophilic spores are highly resistant to heat — thriving in environments up to 100°C — and can survive conditions that would destroy most other microorganisms.
If your autoclave cycle can effectively inactivate these highly resistant spores, you can be confident that your sterilization process is robust and reliable.
How the Spore Test Works
Unlike autoclave tape, which responds only to surface temperature, a BI directly measures actual microbial inactivation through a straightforward process:
- Placement: Place a self-contained BI vial inside the autoclave chamber, ideally alongside your most challenging load (e.g., dense or bulky bio-waste).
- Sterilization Cycle: Run your standard autoclave cycle as usual.
- Incubation: Retrieve and incubate the vial after sterilization to detect any surviving spores.
 |
| Autoclave tape |
Biological indicator |
Decoding the Results: Purple vs. Yellow
- Purple = PASS
If the medium remains purple after incubation, no spores survived. Your autoclave has successfully passed the test.
- Yellow = FAIL
A color change to yellow indicates spore growth and a failed sterilization cycle. Immediate follow-up action is required.
Possible causes of failure include:
- Improper loading of the autoclave
- Incorrect cycle parameters
- Equipment malfunction
- Need for maintenance or repair
In the event of a failure, HSO will work closely with your laboratory to investigate the root cause and arrange prompt re-testing.
 |
| Pass: remains purple |
Fail: color changes to yellow |
About the Workflow of the New Spore Test Service
HSO is implementing a centralized testing workflow for all laboratories handling biological waste to ensure consistency.
Distribution: BI spore test kits will be distributed to laboratories by HSO.
Incubation & Reporting: After performing the test, laboratories should return the BI vial to HSO. Controlled incubation and result reporting will be managed by our central team.
When to Test? Routine monitoring will be coordinated by HSO based on autoclave usage. Laboratory users should notify HSO to arrange additional testing after major repairs, maintenance, or abnormal sterilization cycles.
