Infectious Disease Processes Flashcards

Which mechanism allows bacteria to share resistance genes horizontally across species?

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.

The incubation period of an infectious disease refers to the time between:

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.

Which factor most directly determines whether a pathogen causes infection versus colonization in a host?

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.

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?

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.

Biofilm formation on medical devices is clinically significant primarily because biofilms:

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.

Which type of precautions should be implemented for a patient with confirmed influenza?

Answer: Droplet precautions

Influenza is transmitted primarily via respiratory droplets (>5 microns), requiring droplet precautions including surgical mask and eye protection within 3 feet.

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?

Answer: Common vehicle transmission

Common vehicle transmission occurs when multiple hosts are exposed to a single contaminated source such as food, water, or medication.