CBIC Trivia 5 — Questions and Answers
Question 1: The concept of 'herd immunity' in infection control refers to:
- Natural resistance to infection in a genetically diverse population
- Indirect protection of susceptible individuals when a sufficient proportion of the population is immune (Correct answer)
- The ability of a pathogen to infect multiple animal species
- Immunity conferred by passive antibody transfer
Correct answer: Indirect protection of susceptible individuals when a sufficient proportion of the population is immune
Herd immunity occurs when enough of a population is immune to a disease, reducing its spread and protecting those who cannot be vaccinated.
Question 2: Which of the following best describes a 'common source' outbreak?
- An outbreak where a pathogen spreads person-to-person across multiple generations
- An outbreak where multiple cases share exposure to the same contaminated source (Correct answer)
- An outbreak limited to a single nursing unit
- An outbreak caused by airborne transmission of a novel pathogen
Correct answer: An outbreak where multiple cases share exposure to the same contaminated source
In a common-source outbreak, cases are linked to a single point or continuous exposure source such as contaminated water or food.
Question 3: Which disinfectant class is considered a HIGH-level disinfectant when used at appropriate concentrations and contact times?
- Quaternary ammonium compounds
- Glutaraldehyde (Correct answer)
- Isopropyl alcohol (70%)
- Phenolic compounds
Correct answer: Glutaraldehyde
Glutaraldehyde (e.g., Cidex) achieves high-level disinfection in 20–90 minutes and sterilization with extended soaking, making it appropriate for semicritical items.
Question 4: CRE stands for carbapenem-resistant Enterobacteriaceae. Which enzyme is most commonly responsible for carbapenem resistance in Klebsiella pneumoniae in the United States?
- Extended-spectrum beta-lactamase (ESBL)
- KPC (Klebsiella pneumoniae carbapenemase) (Correct answer)
- NDM-1 (New Delhi metallo-beta-lactamase)
- OXA-48-like carbapenemase
Correct answer: KPC (Klebsiella pneumoniae carbapenemase)
KPC is the most prevalent carbapenemase mechanism in the U.S., particularly in Klebsiella pneumoniae, and is encoded on transferable plasmids.
Question 5: According to the CDC, a central line-associated bloodstream infection (CLABSI) is defined as a laboratory-confirmed bloodstream infection in a patient who had a central line within how many days before the infection?
- 24 hours
- 2 days (Correct answer)
- 3 days
- 7 days
Correct answer: 2 days
NHSN defines CLABSI as a BSI where the patient had a central line on the date of the event or within the 2 days before, with no other recognized infection source.
Question 6: Which isolation precaution category uses a single-occupancy room with positive air pressure and HEPA filtration?
- Airborne infection isolation
- Contact precautions
- Droplet precautions
- Protective environment (PE) (Correct answer)
Correct answer: Protective environment (PE)
Protective environment rooms with positive pressure and HEPA filtration are used for severely immunocompromised patients such as allogeneic hematopoietic stem cell transplant recipients.
Question 7: The 'index case' in an outbreak investigation refers to:
- The most severely ill patient in the outbreak
- The first identified case that triggers investigation (Correct answer)
- The patient most likely responsible for spreading the infection
- The case with the highest bacterial load
Correct answer: The first identified case that triggers investigation
The index case is the first case identified and reported that initiates the outbreak investigation, though it may not be the true primary case.
CBIC Trivia 5
The concept of 'herd immunity' in infection control refers to: