CER High-Level Disinfection Processes Questions and Answers 2 — Questions and Answers

Question 1: What is the minimum effective concentration (MEC) for glutaraldehyde used in high-level disinfection?

0.5%
1.0%
1.5% (most products require ≥1.5% per EPA label) (Correct answer)
3.4% always

Correct answer: 1.5% (most products require ≥1.5% per EPA label)

The MEC for glutaraldehyde HLD is typically 1.5% (product-specific; always confirm with the manufacturer's label and EPA registration).

Glutaraldehyde solutions become diluted with use and over time as organic matter depletes the active concentration. Each product's EPA-registered label specifies its MEC (commonly 1.0–1.5%). Before using glutaraldehyde for HLD, the concentration must be tested with product-specific chemical test strips. If the reading is below MEC, the solution must be discarded regardless of whether the reuse interval has been reached.

Question 2: What is the contact time for ortho-phthalaldehyde (OPA) at room temperature for high-level disinfection?

5 minutes
12 minutes at ≥20°C (per FDA clearance and manufacturer IFU) (Correct answer)
20 minutes at room temperature
45 minutes at room temperature

Correct answer: 12 minutes at ≥20°C (per FDA clearance and manufacturer IFU)

OPA (e.g., Cidex OPA) requires a minimum 12-minute contact time at ≥20°C for HLD per its FDA-cleared label.

OPA (0.55%) has an FDA-cleared contact time of 12 minutes at ≥20°C for semi-critical devices. Its key advantages over glutaraldehyde include faster action, lower vapor pressure (less irritating), and no activation step. However, OPA stains proteins gray (skin, mucosa, fabrics) and requires thorough rinsing. It has a maximum reuse life per manufacturer IFU and must be tested before use. Contact time must not be shortened.

Question 3: Why must endoscopes be thoroughly rinsed after HLD with glutaraldehyde or OPA?

To activate the disinfectant inside the channels
To remove chemical residues that can cause patient injury such as colitis or mucosal irritation (Correct answer)
To lower the temperature of the scope before use
To check for channel blockages

Correct answer: To remove chemical residues that can cause patient injury such as colitis or mucosal irritation

Residual HLD chemicals can cause chemical colitis, mucosal irritation, or allergic reactions in patients if not completely rinsed from channels.

Retained glutaraldehyde or OPA in endoscope channels has caused chemical colitis, proctitis, and esophagitis in patients. Documented outbreaks have occurred when rinsing steps were shortened or tap water was substituted for sterile/filtered water. Rinsing must use the volume and quality of water specified by the endoscope and disinfectant manufacturer's IFU. Typically three sequential rinses through all channels with sterile or filtered water are required.

Question 4: Which professional organization publishes guidelines specifically for endoscope reprocessing for GI endoscopy settings?

APIC only
SGNA (Society of Gastroenterology Nurses and Associates) (Correct answer)
OSHA only
AORN only

Correct answer: SGNA (Society of Gastroenterology Nurses and Associates)

SGNA publishes the primary practice guidelines for endoscope reprocessing specifically for GI endoscopy settings.

SGNA (Society of Gastroenterology Nurses and Associates) publishes its 'Standards of Infection Prevention in Reprocessing of Flexible Gastrointestinal Endoscopes,' which is the primary clinical guideline for GI endoscope reprocessing. Other organizations (APIC, AORN, AAMI) also publish relevant guidelines, and IAHCSMM covers broader sterile processing. CER candidates must be familiar with SGNA guidelines as they are foundational to the certification content.

Question 5: What is the maximum reuse life of most glutaraldehyde solutions used for HLD?

7 days from preparation
14–28 days per manufacturer IFU, provided concentration remains above MEC on each test (Correct answer)
6 months if stored in a dark container
Unlimited if stored correctly

Correct answer: 14–28 days per manufacturer IFU, provided concentration remains above MEC on each test

Glutaraldehyde has a maximum reuse life (typically 14–28 days depending on product) but must be discarded sooner if concentration falls below MEC.

Glutaraldehyde solutions are activated before use (often by adding an alkalinizing agent) which starts the clock on their reuse life — typically 14 days for 2.4–2.65% products, though some brands allow 28 days. However, each use dilutes the solution and reduces active concentration. The solution must be tested with MEC strips before each use; if it falls below MEC at any time before the reuse life expires, it must be discarded. Both criteria (time AND concentration) must be met.

Question 6: What is the difference between 'disinfection' and 'sterilization' in the context of endoscope reprocessing?

There is no practical difference
Disinfection reduces most microorganisms but does not reliably eliminate all spores; sterilization destroys or inactivates all forms of microbial life including spores (Correct answer)
Sterilization is only used for surfaces, disinfection for instruments
Disinfection is more effective than sterilization

Correct answer: Disinfection reduces most microorganisms but does not reliably eliminate all spores; sterilization destroys or inactivates all forms of microbial life including spores

Disinfection (including HLD) eliminates vegetative bacteria, fungi, mycobacteria, and viruses but may not reliably kill all bacterial spores; sterilization achieves complete microbial elimination.

High-level disinfection eliminates all microorganisms except high numbers of bacterial spores. For semi-critical items like endoscopes used on intact mucous membranes, HLD provides adequate safety because intact mucous membranes are resistant to infection from spore-forming organisms under normal conditions. Sterilization, by contrast, achieves a SAL of 10⁻⁶ against all microbial life including spores. Critical items entering sterile tissue or the bloodstream require the absolute safety margin of sterilization.

CER High-Level Disinfection Processes Questions and Answers 2

What is the minimum effective concentration (MEC) for glutaraldehyde used in high-level disinfection?