Bacterial Disease

Front 1

What are 4 potential outcomes from microorganism encounters in the environment?

Back 1

1) Pass through the body as a harmless transient
2) Colonize the body and become part of the normal flora
3) Establish an infection in the body
4) Establish an infection in the body and cause disease

Front 2

Pathogenicity

Back 2

Ability of an organism to cause disease and is a qualitative concept

Front 3

Pathogen

Back 3

Bacterium that is capable of harming a normal host
-(Note that capable means that it may cause harm to a normal host, but does not mean it always will.)
-Normal host means an individual whose defence mechanisms are not compromised in any substantal fashion

Front 4

Opportunistic pathogen

Back 4

Is a bacterium that harms a compromised host, (ie a host whose immune defence system is weakened.)

Front 5

Virulence

Back 5

Is a measure of the pathogenicity of a microorganism
-It is a quantitative concept
-It is expressed as the cell number that will elicit a pathogenic response in the host within a given time

Front 6

Pathogenicity

Back 6

Refers to the ability of an organism to cause disease (ie, harm the host) and represents a genetic component of the pathogen

Front 7

Commensals and opportunistic pathogens

Back 7

-Lack the inherent ability to cause disease

Front 8

What is a property of host-pathogen interactions?

Back 8

damage or injury to the host

Front 9

Virulence

Back 9

The property of the organism that determines the extent of the disease
-The extent of the virulence is usually correlated with the ability of the pathogen to multiply within the host and may be affected by factors such as route of entry and the general health/susceptibility of the host

Front 10

Many microorganisms can be defined as a pathogen and depending upon conditions within the host, may exhibit different levels of virulence
What are the different levels called?

Back 10

-A highly virulent organism causes disease in most individuals with whom it comes in contact
-An avirulent organism rarely, if ever, causes disease in human beings
-Between these two extremes there is a range of virulence possessed by microorganisms
-The virulence of microorganisms is directly attributble to the fact that they possesses certain factors (called virulence factors) which allow it to enter and colonize in the host, resist the immune defences of the host, and cause damage in the host

Front 11

Define:
Primary infection
Secondary Infection
Subclinical Infection
Nosocomial Infection

Back 11

Primary infection - is an initial acute infection
Secondary infection - is a later (or second) infection caused by an opportunistic organism after a primary infection has weakened the host defences
Subclinicial infection -is one in which the host has no apparent symptoms
Nosocomial infection - is one acquired as a consequence of hospitalization

Front 12

Local infection

Back 12

Is restricited to a relatively small area of the body. These infections are usually caused by non-invasive organisms

Front 13

Systemic or generalized infection

Back 13

Is an infection that is spread throughout the body. These infections are often caused by invasive organisms

Front 14

Focal Infection

Back 14

Begins in a restricted area and then spreads throughout the body

Front 15

What are the factors that can compromise the immune defences, leaving the host more susceptibile to infection?

Back 15

1) Underlying disease or infection (AIDS, cancer, inherited immunodeficiencies)
2) Stress
3) Poor nutrition (no essential vitamins or minerals)
4) Age (underdeveloped immune defences of the newborn and infant leave them more suceptible to infection with microorganisms to which the older child or healthy adult is immune. The degeneration of the immune responses which comes with age results in older people being more susceptible to infection)
5) Immunosuppressive therapy (like the therapy used for treatment of cancers or maintence of transplated organs)
6) Genetics of host defence systems. Individuals in population respond differently to infection. Genetic diseases can affect susceptibility to infection (cystic fibrosis and lung infection) In addition, some individuals are more resistant or susceptible to infections than others)