Positive Biological Indicator in a Steam Load
A 280-bed community hospital runs three gravity-displacement steam sterilizers. At 06:00 the Bowie-Dick test on Sterilizer 2 passes. The first load contains 14 instrument sets, including one total knee tray with a titanium implant, sterilized at 132°C for 4 minutes with a 20-minute dry time. A self-contained biological indicator from the center of the load is incubated; at 18 hours it reads positive. Chemical indicators in the load show acceptable color change. The OR has already been told the knee tray will be ready by 09:00. The sterile processing manager wants to release the non-implant sets because only one BI failed and the Bowie-Dick passed. Sterilizer 2 is the only unit available for afternoon add-on cases.
1. What should the manager do immediately with the load, the sterilizer, and the OR schedule? Justify the recall scope.
Read the worked answer
Do not release the load. A positive BI is evidence that the cycle may not have achieved the required sterility assurance level. A passed Bowie-Dick only shows air removal and steam penetration; it does not prove lethality.
- Quarantine every item in the load, including the non-implant sets. The knee tray is an implant load and must not be implanted; notify the surgeon and OR immediately.
- Recall all items processed in Sterilizer 2 since the last confirmed negative BI, plus any load with pending BI results. The recall scope is based on the last verified negative BI, not just the single failing cycle.
- Remove Sterilizer 2 from service. Use another validated sterilizer or adjust the schedule; do not substitute chemical-indicator release for BI release.
- Notify infection prevention and risk management. If an implant from a recalled prior load was already implanted, follow the facility's patient-notification policy.
Rationale: the cost of delaying cases is lower than the risk of releasing non-sterile instruments; production pressure does not change release criteria.
2. What investigation and verification steps are needed before returning Sterilizer 2 to service?
Read the worked answer
Investigate in this order:
- Rule out BI handling error - check BI lot, expiration, storage, incubation temperature and time, positive and negative controls, and whether the BI was crushed or contaminated. A false positive is possible, but it must be proven, not assumed.
- Review the cycle record - temperature, pressure, exposure time, dry time, alarms, and load configuration. Check for overloading, dense containers, wrong shelf, or items touching chamber walls.
- Inspect the sterilizer - door gasket, chamber drain strainer, steam supply quality, non-condensable gases, and calibration. For a gravity-displacement unit, a vacuum leak test is not applicable; focus on air removal, steam purity, and drain function.
- Retest before return to service - after repair, run the facility's required empty-chamber BI verification (commonly three consecutive negative BIs) and repeat physical and chemical monitoring. Document all results.
If the cause is load configuration, retrain staff and repeat with a test pack before releasing production loads.
3. How should the event be documented and communicated, and what professional or ethical issue is raised by releasing non-implant sets?
Read the worked answer
Document contemporaneously: load number, sterilizer, cycle parameters, BI lot and result, items affected, recall time, notifications, and corrective actions. Do not backdate or alter records. Communicate with the OR, infection prevention, and risk management through a brief factual huddle and a written incident report.
The ethical issue is pressure to release non-implant sets because the Bowie-Dick passed and the schedule is tight. The manager's duty is to protect patients; releasing any item from a positive-BI load would be a knowing deviation from accepted practice. If overruled, escalate in writing through the chain of command and document the concern.