Sub-MRC Endoscope Disinfection Before Afternoon Cases
A GI suite has two automated endoscope reprocessors (AERs) and one manual soaking basin. On Tuesday, the OPA minimum recommended concentration (MRC) test on AER #1 reads 0.28%; the label states MRC is 0.3%. AER #1 is used for four colonoscopes that morning, including one used on a patient with a history of CRE colonization. One scope was precleaned at the bedside but sat 75 minutes before reprocessing because the AER was backed up. The AER cycle completed and the printout shows 'cycle complete.' The scopes are hung in a cabinet with a posted 7-day hang time. At 14:00 the MRC is retested after the solution is changed and reads 0.55%. The nurse manager asks whether the morning scopes can be used for afternoon cases.
1. Can the four morning scopes be used for afternoon cases? What immediate actions are required?
Read the worked answer
No. The OPA concentration was below the label MRC, so high-level disinfection cannot be assumed even though the AER printed “cycle complete.” A completed cycle confirms machine function, not effective chemistry.
- Quarantine all scopes processed in AER #1 after the last passed MRC, including the four morning scopes. Retrieve them from storage and reprocess with fresh OPA before use.
- If any scope was already used after the sub-MRC cycle, notify infection prevention and follow the facility's exposure-review policy.
- Change the OPA, retest MRC, and verify AER function before returning it to service. Document the failed MRC, the affected scopes, and the corrective action.
- Review the 75-minute delay before reprocessing. Prolonged delays allow soil to dry and biofilm to form, reducing disinfection efficacy even with adequate chemistry.
2. How should the CRE-colonized patient's scope be handled, and does CRE require a different high-level disinfection process?
Read the worked answer
CRE is a vegetative bacterium, so OPA high-level disinfection is appropriate when concentration and contact time are met; a special sporicidal step is not required for CRE, unlike for C. difficile spores. The problem here is the sub-MRC solution, not the organism.
Reprocess the scope with fresh OPA for the full labeled contact time, ensuring all channels are connected and the leak test passes. If the scope was used after the inadequate cycle, treat it as a potential exposure and involve infection prevention. Document the organism history, the reprocessing parameters, and the resolution.
3. What process controls should change to prevent recurrence?
Read the worked answer
- Test MRC before each shift or session and log the result; remove the AER from service if the result is below the label MRC.
- Change solution according to the label and facility policy, not only when a test fails.
- Maintain spare AER capacity or staffing so scopes are not held for 75 minutes before reprocessing.
- Audit bedside precleaning and transport timing.
- Train staff that a “cycle complete” printout does not mean effective disinfection if the chemistry failed.
- Track hang time and storage conditions; use the manual basin only under a validated protocol.