1. Bacterial Diseases Intro

Front 1

What is a basic definition of the normal flora?

Back 1

These are trillions of microorgansims that reside on the body without causing disease

Front 2

What kind of a relationship does the cohabitation of the body and the normal flora have?

Back 2

A symbiotic relationship.
In some causes, both the human body and the normal flora benefit from this symbiosis and this is called mutualism.
In other cases, symbiosis is beneficial only to microorganisms and this is called commensalism.

Front 3

How is the human body exposed to microorganisms in the environment?

Back 3

Through 3 ways:
1) Inhalation
2) Ingestion
3) Physical Introduction

Front 4

What are the four potential outcomes from encounters with microorganisms?

Back 4

1) Pass through the body as 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 5

Define: Infection

Back 5

-Invasion or colonization of the body by pathogenic (disease causing) microorganisms, but this does not always result in damage or injury to the body

Front 6

Define: Disease

Back 6

Is damage or injury to the body that impairs function

Front 7

Interaction between the host and the microorganism is a relationship because they both contribute to the final outcome. What is this relationship influenced by?

Back 7

1) Pathogenicity of the microbe
2) The resistance or susceptibility of the host
(Ex: Defence mechansims of the host [ both non-specific (innate immune) and adaptive immune response)

Front 8

Define: Strain

Back 8

A population of bacteria that are all descended from a single cell in a clonal fashion

Front 9

Define: Pathogencity

Back 9

Refers to the ability of an organism to cause disease and is a qualitative concept

Front 10

Define: Pathogen

Back 10

-Is a bacterium that is capable of harming a normal host.
-It may cost harm to a normal host, but does not meant it always will
-Normal host means an individual whose defence mechanisms are not compromised in any substantial fashion

Front 11

Define: Opportunistic pathogen

Back 11

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

Front 12

Define: Virulence

Back 12

Virulence is a measure of the pathogencity of a microorganism
-It is a quantiative concept
-It can be expressed as the cell number that will elicit a pathogenic response in the host within a given time period

Front 13

How are pathogenicity and virulence related?

Back 13

Pathogenicity is the ability of an organism to cause disease (harm the host) and represents a genetic component of the pathogen
-Virulence is the property of the organism that determines the extent of the disease and pathogens can express a wide range of virulence

Front 14

Define: Commensals

Back 14

Living together and not causing harm
-Bacteria of the normal flora and opportunistic pathogens lack the inherent ability to cause disease therefore they are commensals

Front 15

What is the extent of virulence usually correlated with?

Back 15

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 16

What is a highly virulent organism?

Back 16

It causes disease in most individuals with whom it comes in contact

Front 17

What is a virulent organsim

Back 17

It rarely causes disease in human beings

Front 18

What is the virulence of microorganisms attributed to?

Back 18

The fact that they possess certain factors called virulence factors which allow it to enter and colonize in the host, resist the immune defenses of the host and cause damage in the host

Front 19

Define the following:
Primary Infection
Secondary Infection
Subclinical infection
Nosocomial Infection

Back 19

Primary infection = initial acute infection
Secondary infection = is a later or second infection caused by opportunistic organism after a primary infection has weakened the host defenses
Subclinical infection - is one in which the host has no apparent symptoms
Nosocmial infection - is acquired as a consequence of hospitalization

Front 20

Infections may be classified by the extent of host involvement which is influenced by the invsiveness of the organism.
Define: Invasiveness

Back 20

-The ability of the organism to invade beyond the original site of entry into the host's body

Front 21

Local infection
Systemic or generalized infection
Focal infection
Define

Back 21

Local infection - is restricted to a relatively small area of the body. These are caused by non-invasive organisms
-Systemic infection is one which is spread throughout the body. These infections are often caused by invasive organisms
-Focal infection begins in a restricted area and then spread throughout the body

Front 22

What can also influence the outcome of an infection/

Back 22

Host susceptibility influences the outcome during the infection
-Interaction between microorganisms and the host is affected by the virulence of the microorganisms and the anti-bacterial defenses of the host
-Susceptibility to infection is increased if the anti-bacterial defences of the host are compromised

Front 23

What are the 6 factors that compromise the host?

Back 23

1) Underlying disease or infection (AIDS, cancer, inherited immunodeficienceis)
2) Stress
3) Poor nutrition (diet w/o essential nutrients)
4) Age (underdeveloped immune defences of the newborn and infat leave them susceptibile to infection w/ microorganism to which the older child or health adult is immune. Also there is degeneration of immune repsonses which comes with age results in older people being more susceptible to infection
5) Immunosuppressive therapy (such as therapy used in cancers)
6) Genetics of host's defence systems. Some are more resistant and some are more susceptible)

Front 24

Bacteria with low virulence may cause disease in a ___________

Back 24

compromised host.