CER - Certified Endoscope Reprocessor Endoscope Sterilization Methods Questions and Answers — Questions and Answers
Question 1: A reprocessing facility is validating its Ethylene Oxide (EtO) sterilization cycle for flexible endoscopes. Which of the following sets of parameters are all essential for achieving effective EtO sterilization?
- Gas concentration, temperature, pressure, and aeration time
- Gas concentration, temperature, relative humidity, and exposure time (Correct answer)
- Pre-vacuum depth, gas concentration, exposure time, and post-cycle purge
- Temperature, relative humidity, cycle duration, and biological indicator placement
Correct answer: Gas concentration, temperature, relative humidity, and exposure time
Effective Ethylene Oxide (EtO) sterilization depends on four critical parameters: gas concentration (typically 450 to 1200 mg/l), temperature (37 to 63°C), relative humidity (40 to 80%), and exposure time (1 to 6 hours). All four must be within the specified ranges for the cycle to be effective. While pressure and aeration time are parts of the overall process, they are not considered the four essential parameters for achieving sterility.
Question 2: A facility is considering a low-temperature sterilization method for its new heat-sensitive flexible duodenoscopes. They need a method that uses a vapor, is converted to a plasma state to enhance microbial kill, and breaks down into non-toxic byproducts like oxygen and water. Which sterilization method fits this description?
- Peracetic Acid Immersion
- Ethylene Oxide (EtO)
- Vaporized Hydrogen Peroxide Gas Plasma (Correct answer)
- Ozone Sterilization
Correct answer: Vaporized Hydrogen Peroxide Gas Plasma
Vaporized Hydrogen Peroxide (VHP) Gas Plasma sterilization uses hydrogen peroxide vapor which is then excited by an electric field into a plasma state. This process generates free radicals that are highly effective at killing microorganisms. A key advantage is that at the end of the cycle, the byproducts are non-toxic water and oxygen, eliminating the need for lengthy aeration.
Question 3: According to ANSI/AAMI ST91, what is the recommended practice for endoscopes that have been processed using a liquid chemical sterilization (LCS) system but are not intended for immediate use?
- They can be stored with a claim of being sterile for up to 7 days.
- They must be dried with 70% isopropyl alcohol and then packaged in a sterile container.
- They should be used immediately, as storage is not recommended for liquid chemically sterilized items.
- They can be stored in the same manner as endoscopes that have undergone high-level disinfection. (Correct answer)
Correct answer: They can be stored in the same manner as endoscopes that have undergone high-level disinfection.
ANSI/AAMI ST91 states that liquid chemically sterilized endoscopes intended for critical procedures should be used immediately. If not for immediate use, they can be stored in the same way as endoscopes that have undergone high-level disinfection (HLD), which involves thorough drying and storage in a clean, dedicated cabinet. They should not be stored with a claim of being patient-ready sterile.
Question 4: A reprocessing technician is using an Automated Endoscope Reprocessor (AER) that utilizes a peracetic acid-based system for liquid chemical sterilization. What is the primary mechanism by which peracetic acid inactivates microorganisms?
- Alkylation of proteins and nucleic acids
- Oxidation of cell components (Correct answer)
- Coagulation of cellular proteins
- Disruption of the cell membrane via a pH change
Correct answer: Oxidation of cell components
Peracetic acid is a highly biocidal oxidizer. Its primary mechanism of action is oxidation, where it denatures proteins, disrupts cell wall permeability, and oxidizes essential bonds in proteins and enzymes, leading to the shutdown of cellular function and death of the microorganism.
Question 5: Which of the following statements correctly distinguishes sterilization from high-level disinfection (HLD) in the context of endoscope reprocessing?
- Sterilization kills all microorganisms including viruses, while HLD only kills bacteria and fungi.
- HLD is the required minimum for critical endoscopes, while sterilization is optional.
- Sterilization provides a sterility assurance level (SAL) by eliminating all viable microorganisms, including large numbers of bacterial spores. (Correct answer)
- HLD uses heat and pressure, whereas sterilization exclusively uses low-temperature chemical methods.
Correct answer: Sterilization provides a sterility assurance level (SAL) by eliminating all viable microorganisms, including large numbers of bacterial spores.
The key difference is the level of microbial kill. Sterilization is a validated process that renders a device free from all viable microorganisms, including high numbers of bacterial spores, achieving a specific sterility assurance level (SAL). High-level disinfection kills all vegetative microorganisms, mycobacteria, viruses, and fungi, but not necessarily large numbers of bacterial spores.
Question 6: A hospital's infection control committee is reviewing its endoscope reprocessing protocols. They note that while their AERs perform an excellent high-level disinfection cycle, the final forced-air drying phase is often incomplete, leaving visible moisture in the channels. This significantly increases the risk of:
- Corrosion of the endoscope's internal components.
- Recontamination and proliferation of waterborne microorganisms. (Correct answer)
- Ineffectiveness of the subsequent leak test.
- Fixation of proteins if the manual cleaning was inadequate.
Correct answer: Recontamination and proliferation of waterborne microorganisms.
Complete drying of endoscope channels after high-level disinfection is a critical step. Any remaining moisture can create an environment that allows for the recontamination and proliferation of waterborne pathogens, such as Pseudomonas aeruginosa or nontuberculous mycobacteria, compromising the safety of the reprocessed endoscope.
CER - Certified Endoscope Reprocessor Endoscope Sterilization Methods Questions and Answers
A reprocessing facility is validating its Ethylene Oxide (EtO) sterilization cycle for flexible endoscopes.
Which of the following sets of parameters are all essential for achieving effective EtO sterilization?