CER Microbiology and Infection Control 2 — Questions and Answers
Question 1: Which organism is MOST resistant to chemical disinfectants and requires sterilization to eliminate?
- Mycobacterium tuberculosis
- Pseudomonas aeruginosa
- Bacterial endospores (Clostridium) (Correct answer)
- Hepatitis B virus
Correct answer: Bacterial endospores (Clostridium)
Bacterial endospores such as those from Clostridium species are the most resistant microbial forms and require sterilization, not just disinfection, for elimination.
Question 2: A high-level disinfectant must be capable of killing all of the following EXCEPT:
- Vegetative bacteria
- Mycobacteria
- Bacterial spores (all concentrations) (Correct answer)
- Lipid and non-lipid viruses
Correct answer: Bacterial spores (all concentrations)
High-level disinfection kills vegetative bacteria, mycobacteria, and viruses but does NOT reliably kill all bacterial spores — that requires sterilization.
Question 3: Which term describes the number of viable organisms present on or in a device before reprocessing begins?
- Bioburden (Correct answer)
- Biofilm
- Colony count
- Microbial load index
Correct answer: Bioburden
Bioburden refers to the total number of viable microorganisms on a device prior to any cleaning or disinfection process.
Question 4: What is the primary reason point-of-use pre-cleaning (bedside flushing) is critical in endoscope reprocessing?
- It replaces the manual cleaning step
- It prevents biofilm formation by removing organic matter before it dries (Correct answer)
- It disinfects the endoscope immediately after use
- It satisfies OSHA bloodborne pathogen requirements
Correct answer: It prevents biofilm formation by removing organic matter before it dries
Bedside pre-cleaning prevents organic material from drying inside channels, which would make it far more difficult to remove and could facilitate biofilm development.
Question 5: Which type of hepatitis virus is classified as MOST resistant to chemical inactivation?
- Hepatitis A
- Hepatitis B (Correct answer)
- Hepatitis C
- Hepatitis D
Correct answer: Hepatitis B
Hepatitis B virus is notably more resistant to chemical disinfectants than Hepatitis A, C, or D, requiring high-level disinfection for reliable inactivation.
Question 6: In the context of infection control, what does the term 'reservoir' refer to?
- A storage container for disinfectants
- The habitat where an infectious agent normally lives and multiplies (Correct answer)
- The transport medium for culture specimens
- A holding tank for used endoscopes
Correct answer: The habitat where an infectious agent normally lives and multiplies
A reservoir is the natural habitat (human, animal, or environment) where a pathogen survives, multiplies, and can be transmitted to susceptible hosts.
Question 7: Which reprocessing step is MOST critical for preventing transmission of prion diseases (e.g., Creutzfeldt-Jakob disease) via endoscopes?
- High-level disinfection with glutaraldehyde
- Steam autoclave sterilization at standard settings
- Thorough manual cleaning to remove protein material (Correct answer)
- Exposure to 70% isopropyl alcohol
Correct answer: Thorough manual cleaning to remove protein material
Prions are resistant to standard sterilization and disinfection; thorough physical removal of proteinaceous material through cleaning is the most effective risk-reduction step.
CER Microbiology and Infection Control 2
Which organism is MOST resistant to chemical disinfectants and requires sterilization to eliminate?