Veterinary Clinic Case Review: Handling a Positive Spore Test and Recall
A positive spore test sent a small animal veterinary clinic in Ontario into a three-day instrument recall and patient trace. This de-identified case review follows how they ran the recall, found the root cause, and returned to surgery.
The positive result: a Thursday load fails
The clinic ran two compact steam sterilizers and challenged each weekly with a biological indicator (BI) — the widely recommended baseline in veterinary settings. Thursday's routine BI in sterilizer #2 came back positive next day: the 24-hour vial had turned colour, so Geobacillus stearothermophilus survived.
Blaming the test was everyone's first instinct — expired vial, warm incubator, bad batch. The owner chose differently: treat it as real, pull the unit from service, and find out what happened. A repeat indicator came back positive too, removing all doubt.
The recall: instruments first, then patients
Every load since the last negative result fell under suspicion. The log narrowed it to three days: fourteen wrapped packs covering eleven procedures, from spays to a cruciate repair. Pack numbers matched patient charts, so the recall was precise, not shotgun.
All fourteen packs went into quarantine and the owners of all eleven animals got calls; incision sites were checked and follow-ups offered where warranted. No patient showed signs of infection, and the log confirmed none of the suspect packs reached a sterile field.
That log is the quiet hero of the case. Without it, the window would have stretched from three days to three weeks of guessing from memory. It is a one-page form — inexpensive insurance.
Root-cause analysis: three compounding problems
A certified technician went through sterilizer #2 while the team reviewed its own habits. The printout looked normal; the real problems sat elsewhere:
- Missed maintenance. The unit was two months past its scheduled service; the drain strainer was matted with hair and the door gasket had a worn spot.
- Dense, overfilled loads. Towel-wrapped instruments were stacked flat past the validated capacity — and towel packs are among the hardest loads for steam to penetrate.
- Packaging mistakes. Pouches were overstuffed, seals ran close to the instruments, and double-wrapping left air no escape.
Every pack carried a chemical indicator, and every one changed colour — that is the trap. Chemical indicators only prove steam reached the package. Whether the load was sterilized is a question only a biological indicator can answer, via living spores per ISO 11138-3.
The corrective plan
The owner turned the findings into four commitments, posted beside each sterilizer:
- Maintenance on a calendar. Service is booked in advance, the drain strainer cleaned daily, the door gasket inspected weekly.
- Disciplined loading. Capacity limits are printed on each machine; pouches stand on edge and nothing touches the chamber walls.
- Standardized packaging. Instruments now go into CliniEco Class 4 dual-indicator sterilization pouches sized so contents never crowd the seal; larger sets are wrapped in CliniEco pre-cut sterilization roll sheets cut to length.
- Faster monitoring. The practice switched to CliniEco 24-hour rapid-readout biological indicators; weekly testing stays the baseline, and the hospital now runs an extra BI in the first load of every surgery day — a pattern busier services often choose.
Retesting and return to service
Recovery followed the ANSI/AAMI ST79 script: three consecutive full loads, each challenged with a biological indicator placed bottom front near the drain. All three were negative at 24 hours; only then were the fourteen quarantined packs re-wrapped and reprocessed.
Weekly monitoring continued for a month, and the incident became a training module — new staff study photos of the failed load.
What other veterinary clinics should take from this case
Three habits carried this practice through a bad week: weekly biological monitoring, a load log for every cycle, and a refusal to explain away a positive result. The failure itself was ordinary — a missed service, a packed chamber, a tired gasket.
For a practice that spore tests weekly and logs every load, a positive BI is a contained, scripted event; for one that does neither, it is a recall with no starting point. So keep the logs honest and indicators in stock.
Frequently Asked Questions
What should a veterinary clinic do when a spore test comes back positive?
Take that sterilizer out of service and quarantine everything processed since the last negative indicator, then trace packs and patients via the load log. After the fix, run three consecutive full cycles with negative biological indicators per ANSI/AAMI ST79. CliniEco 24-hour rapid-readout biological indicators keep each confirmation cycle to one day.
How often should veterinary clinics run biological monitoring on their sterilizers?
Weekly biological monitoring is the widely recommended baseline for veterinary settings, mirroring human healthcare practice under ANSI/AAMI ST79; busier services may test more often, as this clinic now does. A 25-pack of CliniEco rapid-readout biological indicators covers about six months of weekly testing on one sterilizer — twelve weeks on two.
Do chemical indicators on sterilization pouches prove that instruments were sterilized?
No. Chemical indicators, including the Class 4 dual indicators printed on CliniEco sterilization pouches, confirm exposure to steam, not spore kill. Only a biological indicator verifies sterilization — which is why ISO 11138-3 sets strict specifications for the Geobacillus stearothermophilus spores used in testing.
Which instruments and patients must be traced after a failed spore test?
Everything processed since the last negative result — surgical packs, dental instruments, implant trays; here, fourteen packs tied to eleven procedures. A numbered load log matches each pack to a patient chart, so the trace takes hours, not guesswork. Keep CliniEco pre-cut sterilization roll sheets in stock for quick re-wrapping.
Related reading: explore our sterilization compliance hub for every industry that sterilizes.
start with our pillar guide on sterility assurance level (SAL) and what 10⁻⁶ really means.
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