Introduction To Bacteriology

Front 1

What was the earliest scientific belief about microorganisms?

Back 1

Spontaneous generation

- living things can develop from non-living matter

(eg. "rotting meat is the source of flies", "muddy soil gives rise to frogs")

Front 2

Who proved the "Spontaneous generation" theory to be wrong?

Back 2

Louis Pasteur (in 1862)

Front 3

How the "Spontaneous generation" theory was disproven?

Back 3

Through the flask experiment.

# flask's neck - S-shape form

=> it trapped bacteria in the middle

# sterile broth didn't get bacteria growing in it when the S-shaped neck was on (cause it caught the bacteria & broth stayed sterile),

but bacteria grew when the neck was off.

Front 4

What is the conclusion of the Pasteur's flask experiment?

Back 4

# Microorganisms are everywhere - even in the air.

=> Spontaneous generation is wrong

=> led to the development of the Germ theory

Front 5

What is the key postulate of the Germ theory?

Back 5

some or all diseases are caused by microorganisms

Front 6

Koch's postulates

Back 6

1. The bacterium must be present in all cases of the disease.

2. The bacterium must be isolated from the infected host & grown in pure culture.

3. When the pure culture bacterium is inoculated in a healthy susceptible host, that new host must develop the same disease as the original host.

4. The bacterium must be recoverable from that new host.

Front 7

What is "selective toxicity"?

Back 7

a concept developed by Paul Ehrlich, and applicable to

*molecules that kill pathogen but do not harm human cells*.

another name: "magic bullet"

Front 8

What is considered to be one of the single most effective drugs of the 20th century?

Back 8

Penicillin

(developed by Alexander Fleming)

Front 9

What is a "pathogen"?

Back 9

an organism that can invade the body and cause disease

Front 10

What is "pathogenicity"?

Back 10

an ability to cause disease in another organism

Front 11

What is "virulence"?

Back 11

the degree of pathogenicity.

- highly virulent organism can cause disease in low numbers.

Front 12

What is "infection"?

Back 12

Infection is the entry, establishment, and multiplication of pathogens within a host.

Front 13

What are the 2 main ways in which a host defends itself from a pathogen?

Back 13

# Non-specific (not directed at any particular organism);

# Specific (directed at a particular organism, and mediated by the immune system)

Front 14

In which 2 ways does the "Specific" defence operate?

Back 14

# Humoral - (due to specific antobody production);

# Cell-mediated - (due to T lymphocytes and cytokines cells produce)

Front 15

List non-specific defence mechanisms

Back 15

1) Skin,

2) Normal flora,

3) Flushing effect (eg. tears, urine),

4) Gastrointestinal tract (low pH of stomach acid),

5) Vaginal secretions (low pH),

6) Phagocytosis (bacteria & viruses are ingested by 2 types of scavenging cells: Neutrophils & Macrophages),

7) Complement proteins (they enhance phagocytosis & lyse bacteria [eg. C3b protein])