Terminology

Question 1

Opportunistic Pathogen

Answer 1

Causes disease only in individuals whose normal defense mechanisms have been compromised (e.g. burn patients, organ transplant recipients on immunosuppressants, individuals with AIDS, pregnant women)

Question 2

Virulence

Answer 2

Quantitative measure of pathogenesis

Question 3

LD50

Answer 3

The lethal dose 50,is the number of microorganisms (or amount of a toxin) required to kill 50% of the test animals.

Question 4

ID50

Answer 4

Infectious dose 50,is the number of organisms(or amount of a toxin) required to produce an infection in 50% of the test animals.

Question 5

Virulence Factors

Answer 5

Components of the pathogen responsible for its ability to cause an infection. Often defined by mutations in specific genes (virulence genes) which result in lower virulence (increased LD50).

Question 6

Pathogenesis is multifactorial

Answer 6

Usually involving numerous determinants of pathogenicity. Loss of
individual determinants may not necessarily result in reduced virulence.

Question 7

Pleiotropic

Answer 7

Mutations resulting in avirulence are pleiotropic, mapping to a gene involved in regulation of multiple virulence factors.

Question 8

Obligate Pathogen

Answer 8

Has not been found in anywhere but in association with its host.
Implications for disease eradication.

Question 9

Facultative Pathogen

Answer 9

Can grow or survive in the environment and its host.

Question 10

Obligate Intracellular Pathogen

Answer 10

Can only grow inside of host cells, and cannot be cultured extracellularly.

Question 11

Facultative Intracellular Pathogens

Answer 11

Can grow both inside and outside of cells and may be cultured on agar surface in lab.

Question 12

Pathogen

Answer 12

A microorganism capable of producing disease in a % of normal individuals (colonization without disease in asymptomatic carriers.