CER Microbiology and Infection Control Questions and Answers 3 — Questions and Answers
Question 1: Which type of hepatitis virus is MOST commonly transmitted via contaminated endoscopes due to inadequate reprocessing?
- Hepatitis A
- Hepatitis B
- Hepatitis C (Correct answer)
- Hepatitis E
Correct answer: Hepatitis C
Hepatitis C virus (HCV) is the most frequently transmitted bloodborne pathogen linked to endoscope reprocessing failures in documented outbreaks.
Question 2: What is the minimum contact time required for a high-level disinfectant to achieve its labeled efficacy against high-level disinfection organisms?
- The manufacturer's minimum stated exposure time at the labeled concentration and temperature (Correct answer)
- Any time greater than 1 minute at room temperature
- 5 minutes regardless of product or temperature
- 10 minutes at 20°C for all approved HLDs
Correct answer: The manufacturer's minimum stated exposure time at the labeled concentration and temperature
Efficacy depends on following the exact manufacturer-specified contact time, concentration, and temperature parameters validated during FDA clearance.
Question 3: Pseudomonas aeruginosa is a significant concern in endoscope reprocessing primarily because it:
- Forms heat-stable toxins that survive autoclaving
- Can colonize waterlines and recontaminate scopes during rinsing (Correct answer)
- Is a spore-forming organism resistant to glutaraldehyde
- Requires prion-level decontamination protocols
Correct answer: Can colonize waterlines and recontaminate scopes during rinsing
P. aeruginosa thrives in biofilms within water supply lines and rinse water, making it a major source of post-HLD recontamination.
Question 4: A biofilm found on the inner channel of an endoscope is MOST problematic because it:
- Increases the pH of disinfectant solutions reducing efficacy
- Physically protects embedded microorganisms from chemical disinfectants (Correct answer)
- Generates endotoxins that destroy endoscope optics
- Accelerates corrosion of metallic instrument channels
Correct answer: Physically protects embedded microorganisms from chemical disinfectants
The extracellular polysaccharide matrix of biofilm shields bacteria from liquid chemical disinfectants, making thorough mechanical cleaning before HLD critical.
Question 5: Which organism is used as the biological indicator to validate sterilization processes in most US healthcare settings?
- Clostridium difficile spores
- Geobacillus stearothermophilus spores (Correct answer)
- Mycobacterium terrae
- Bacillus cereus
Correct answer: Geobacillus stearothermophilus spores
Geobacillus stearothermophilus spores are the standard biological indicator for steam sterilization because of their high heat resistance.
Question 6: When performing leak testing on a flexible endoscope, a continuous stream of bubbles from the insertion tube indicates:
- Normal air purging from the water channel
- A breach in the external sheath requiring repair before reprocessing continues (Correct answer)
- Successful pressure equalization
- Over-inflation of the air supply tube
Correct answer: A breach in the external sheath requiring repair before reprocessing continues
Continuous bubbling from the insertion tube signals a perforation or defect in the sheath that would allow fluid ingress and damage internal components.
Question 7: The Spaulding Classification system categorizes flexible GI endoscopes as 'semicritical' because they:
- Enter sterile body cavities and contact sterile tissue
- Contact mucous membranes but do not penetrate sterile tissue (Correct answer)
- Contact only intact skin without mucous membrane involvement
- Are implanted devices requiring permanent sterilization
Correct answer: Contact mucous membranes but do not penetrate sterile tissue
Semicritical items contact mucous membranes or non-intact skin, requiring at minimum high-level disinfection rather than sterilization.
CER Microbiology and Infection Control Questions and Answers 3
Which type of hepatitis virus is MOST commonly transmitted via contaminated endoscopes due to inadequate reprocessing?