Lecture 2: Microbio Introduction

Front 1

Koch's Postulates:

Purpose
Name them

Back 1

Purpose: to detect organism causing infectious disease

1. Org always found in diseased animal but not in healthy animal
2. Org can be isolated and grown in pure culture away from animal
3. Isolated org causes disease in new animal
4. Same org re-isolated from new diseased animal

(if disease then org; org growable; grown org creates diseases; grown disease org isolatable)

Front 2

Limitation of Koch's postulates

Back 2

Some orgs can't be grown w/o host
No animal models for some human diseases
Some diseases caused by many orgs
Carrier States (org but no disease)

Front 3

Molecular Koch's Postulates

Purpose
Name them
What's a transposon for?

Back 3

Purpose: detemine if factor is important for causing diseases (virulence factor)

1. Phenotype encoded by virulence gene should be associated with pathogenic strains
2. Inactivation of gene causes measurable loss of virulence
3. Addition of cloned copy of gene to mutant w/o it should restore virulence

-- inactive via Transposons

Front 4

Virulence

LD50, ED50

Back 4

# orgs to START infection

1/2 a Lethal Dose
1/2 an Effective Dose (define effective as you desire)

Front 5

Infectious Cycle includes: (6)

Back 5

Pathogen...

Entry
Adherence/colonization
Invasion through epithelium (optional)
Evasion of host defenses
Damage to cells/tissues via toxins or immunopathology
Dissemination of pathogen to new host

Front 6

Infection v. Intoxication

Back 6

Infection = pathogen in body produces toxins
Intoxication = toxin in body (but no pathogen)

Front 7

Advantages
Disadvantages

of INTRAcellular Pathogens

Back 7

Ad:
Nutrients supplied by cell
Pathogen protected from initial immune response and some antibiotics

Dis:
Cells kill invaders well so pathogen needs good strategy
This requires lots of Energy use and lots of DNA space

Front 8

List:

**Obligate INTRAcellular Pathogens

(viruses/bacteria/fungi/parasites)

Back 8

Viruses: all

Bacteria:
Mycobacterium leprae
Chlamydiae spp.
Rickettsia spp.

Fungi/Parasites: none

Front 9

List:

Facultative INTRAcellular Pathogens

(viruses/bacteria/fungi/parasites)

Back 9

Bacteria:
Salmonella spp.
Shigella
Listeria monocytogenes
Legionella
Mycobacterium tuberculosis

*Fungi: Most
*Parasites: Most

Front 10

List:

Extracellular Pathogens

(viruses/bacteria/fungi/parasites)

Back 10

Bacteria:
*most Gram Positive except Listeria monocytogenes
Vibrio cholera
Treponema pallidum

Fungi: Cryptococcus
Parasites: Giardia