CIC Infectious Disease Processes 3 — Questions and Answers
Question 1: Which mechanism allows bacteria to share resistance genes horizontally across species?
- Binary fission
- Transduction only
- Conjugation via plasmids (Correct answer)
- Sporulation
Correct answer: Conjugation via plasmids
Conjugation allows direct transfer of plasmids carrying resistance genes between bacteria, even across different species, driving the spread of antimicrobial resistance.
Question 2: The incubation period of an infectious disease refers to the time between:
- Exposure to a pathogen and the appearance of symptoms (Correct answer)
- Symptom onset and resolution of illness
- Initial infection and development of immunity
- Colonization and transmission to another host
Correct answer: Exposure to a pathogen and the appearance of symptoms
The incubation period is the interval between initial exposure to (or infection by) a pathogen and the first appearance of signs or symptoms.
Question 3: Which factor most directly determines whether a pathogen causes infection versus colonization in a host?
- Geographic origin of the pathogen
- Balance between host immune defenses and pathogen virulence (Correct answer)
- Temperature of the environment
- Duration of prior antibiotic therapy
Correct answer: Balance between host immune defenses and pathogen virulence
Whether disease occurs depends on the interplay between the virulence of the organism and the strength of the host's immune defenses.
Question 4: A healthcare worker is exposed to a patient's blood through a needlestick. Which bloodborne pathogen has the highest risk of transmission per exposure event?
- HIV
- Hepatitis C virus (HCV)
- Hepatitis B virus (HBV) (Correct answer)
- Human T-lymphotropic virus (HTLV)
Correct answer: Hepatitis B virus (HBV)
HBV has the highest transmission risk per needlestick exposure (6–30%) compared to HCV (~1.8%) and HIV (~0.3%) in unvaccinated individuals.
Question 5: Biofilm formation on medical devices is clinically significant primarily because biofilms:
- Increase the speed of bacterial replication
- Protect bacteria from disinfectants and immune defenses (Correct answer)
- Prevent the bacteria from becoming antibiotic resistant
- Are easily eradicated with standard antibiotic therapy
Correct answer: Protect bacteria from disinfectants and immune defenses
Biofilms encase bacteria in a polysaccharide matrix that significantly increases resistance to both antimicrobial agents and host immune responses.
Question 6: Which type of precautions should be implemented for a patient with confirmed influenza?
- Airborne precautions
- Contact precautions only
- Droplet precautions (Correct answer)
- Standard precautions only
Correct answer: Droplet precautions
Influenza is transmitted primarily via respiratory droplets (>5 microns), requiring droplet precautions including surgical mask and eye protection within 3 feet.
Question 7: An outbreak investigation reveals that multiple patients developed Salmonella infections linked to contaminated eggs served in the hospital cafeteria. This represents which mode of transmission?
- Vector-borne transmission
- Airborne transmission
- Common vehicle transmission (Correct answer)
- Direct contact transmission
Correct answer: Common vehicle transmission
Common vehicle transmission occurs when multiple hosts are exposed to a single contaminated source such as food, water, or medication.
CIC Infectious Disease Processes 3
Which mechanism allows bacteria to share resistance genes horizontally across species?