CIC Infectious Agent Transmission 5 — Questions and Answers
Question 1: An infection preventionist notes MRSA transmission persisting despite contact precautions. Which environmental factor should be investigated FIRST?
- Air handling and HEPA filtration in patient rooms
- Adequacy of terminal room cleaning and disinfection practices (Correct answer)
- Water supply contamination with MRSA
- Arthropod vectors in the facility
Correct answer: Adequacy of terminal room cleaning and disinfection practices
MRSA survives on environmental surfaces for extended periods; inadequate terminal cleaning is a common cause of ongoing contact transmission despite isolation precautions.
Question 2: The concept of 'infectious dose' in transmission refers to:
- The amount of antibiotic required to eliminate an infection
- The minimum number of pathogenic organisms needed to establish infection in a host (Correct answer)
- The duration of antibiotic therapy for a specific pathogen
- The quantity of pathogen shed by an infected host per day
Correct answer: The minimum number of pathogenic organisms needed to establish infection in a host
Infectious dose is the minimum number of organisms required to successfully establish infection in a susceptible host, and varies widely among different pathogens.
Question 3: Hepatitis B virus (HBV) transmission in healthcare settings is MOST efficiently prevented by:
- Placing all HBV-positive patients in contact isolation
- Vaccination of healthcare workers and use of standard precautions (Correct answer)
- Treating all patient blood as non-infectious
- Requiring N95 respirators for all patient care
Correct answer: Vaccination of healthcare workers and use of standard precautions
HBV vaccination provides the most effective protection, and standard precautions (treating all blood/body fluids as infectious) prevent occupational exposure.
Question 4: Which scenario represents vertical transmission of an infectious agent?
- A food handler spreads norovirus to restaurant patrons
- HIV transmission from a mother to her infant during delivery (Correct answer)
- Influenza spreading between hospital roommates
- Malaria transmission via mosquito bite
Correct answer: HIV transmission from a mother to her infant during delivery
Vertical transmission refers to pathogen transfer from parent to offspring, including transplacental, perinatal (during delivery), or breastfeeding transmission.
Question 5: A hospital implements universal gloving for all patient contact. Which unintended consequence is MOST concerning for infection prevention?
- Increased cost of personal protective equipment
- Decreased hand hygiene compliance due to false sense of security (Correct answer)
- Allergic reactions to latex gloves among patients
- Reduced staff efficiency during routine care
Correct answer: Decreased hand hygiene compliance due to false sense of security
Universal gloving can create a false sense of security, leading to reduced hand hygiene compliance, which paradoxically increases transmission risk when gloves are not changed between patients.
Question 6: Epiglottitis caused by Haemophilus influenzae type b (Hib) is transmitted primarily via which route?
- Fecal-oral route through contaminated water
- Direct contact with skin lesions
- Respiratory droplets from the nasopharynx of colonized or infected persons (Correct answer)
- Airborne droplet nuclei requiring negative-pressure isolation
Correct answer: Respiratory droplets from the nasopharynx of colonized or infected persons
Hib is transmitted via respiratory droplets from the nasopharyngeal secretions of colonized or infected individuals, requiring droplet precautions.
Question 7: In outbreak investigation, the attack rate is most useful for:
- Determining the causative pathogen through laboratory analysis
- Measuring the proportion of exposed individuals who develop illness, helping identify the source (Correct answer)
- Calculating the case fatality rate of the disease
- Establishing the environmental persistence of the pathogen
Correct answer: Measuring the proportion of exposed individuals who develop illness, helping identify the source
The attack rate (number ill / number exposed × 100) helps identify the exposure source by comparing rates among those with different exposures during an outbreak.
CIC Infectious Agent Transmission 5
An infection preventionist notes MRSA transmission persisting despite contact precautions.
Which environmental factor should be investigated FIRST?