BacT Lec 3

Question 1

*Pathogenicity

Answer 1

The ability of a pathogen to produce a disease by overcoming the defense mechanisms of the host

Question 2

Virulence

Answer 2

The degree of pathogenicity (factors present in an organism that makes it to cause disease)

Question 3

*Properties or traits found in isolates that cause disease but which are not found in isolates of the same species that lack ability to cause disease

Answer 3

Bacterial Virulence Factors

Question 4

To cause disease a pathogen must:

Answer 4

1) Gain access to the host
2) Adhere to host tissue
3) penetrate or evade host defenses
4) Damage the hose - directly or accumulation of microbial wastes

Question 5

Preferred portals of entry

Answer 5

Mucous membranes
Skin
Parental route

Question 6

ID50

Answer 6

Number of microbes required to produce infection in 50% of the population

Question 7

LD50

Answer 7

The amount of toxin or pathogen necessary to kill 50% of the population in a particular time frame

Question 8

Adhesins

Answer 8

Surface projections on pathogen, mostly made of glycoproteins or lipoproteins. Adhere to complementary receptors on the host cells

Question 9

Adhesins can be part of:

Answer 9

Glycocalyx

Fimbriae (also pili and flagella)

Question 10

What can biofilms provide?

Answer 10

attachment and resistance to antimicrobial agents

Question 11

5 ways to overcome host defenses

Answer 11

1) Capsule
2) Cell wall components
3) Antigenic variation
4) Penetration into the host cell cytoskeleton
5) Production of enzymes

Question 12

Incasins

Answer 12

Alter host cell actin to enter a host cell (Salmonella)

Use actin to move form one cell to the next (listeria)

Question 13

Three ways intracellular bacterial survival following phagocytosis

Answer 13

Escape from phagocytic vacuoles into cytosol
Prevention of lysosomal fusion to phagosomes
resistance to hydrolytic enzymes

Question 14

Exoenzymes

Answer 14

Coagulase
Kinase
Hyaluronidase
Collagenase
IgA protease

Question 15

Two qualities that bacteria underlie the means by which they cause disease

Answer 15

Invasiveness

Toxgenesis

Question 16

Two types of invasiveness

Answer 16

Colonization

Invasion

Question 17

Colonization is?

Answer 17

Adherence and initial multiplication

Question 18

Invasion is

Answer 18

Production of extracellular substance which facilitate invasion

Question 19

Two types of toxigenesis

Answer 19

Endotoxins (Gram-neg only)

Exotoxins (Gram-neg and Gram-pos)

Question 20

Quorum sensing

Answer 20

Bacteria remain innocuous until they reach a certain population and then ambush the immune system

Question 21

Non selective culture media

Answer 21

Liquid (broth)
Solid (Agar media)
Trypticase soy agar with blood (blood agar)

Question 22

How is liquid broth used?

Answer 22

To help bacteria to overcome stress that they have been experience so that we can get them to grow. No isolation is done.

Question 23

Most common culture media

Answer 23

Trypticase soy agar with blood (blood agar)

Question 24

What is the difference in selective media and non selective media?

Answer 24

Non selective media can culture most all bacteria.

Selective media excludes bacteria depending on the type

Question 25

Selective culture media

Answer 25

PEA (Phenylethyl Alcohol Agar) MacConkey Agar Hektoen Entrtic Agar

Question 26

What kind of bacteria does PEA (Phenylethyl Alcohol Agar) culture?

Answer 26

*Gram- Positive

Question 27

What kind of bacteria does MacConkey Agar culture?

Answer 27

*Gram-Negative

Question 28

What is unique about MacConkey Agar?

Answer 28

It is *selective for Gram-Negative and is a *differential media (lactose and neutral turn red & fermentation turn pink)

Question 29

What bacteria does Hektoen Enteric Agar media selective for and differentiates?

Answer 29

E. coli (differentiates from salmonella - black colonies)

Question 30

What makes bacteria identification easier?

Answer 30

More knowledge of the bacteria you are trying to isolate.

Question 31

Most accurate bacteria identification.

Answer 31

MALDI-TOF

Question 32

List the biosafety Levels form lowest to highest

Answer 32

BSL 1, BSL 2, BSL 3, BSL 4

Question 33

What is the purpose of biosafety levels?

Answer 33

Minimize potential exposure to a biohazard for lab personnel and others

Question 34

What level do all laboratories operate on?

Answer 34

BSL 2

Question 35

What level is for agents that there is no treatment available.

Answer 35

BSL 4

Question 36

List examples of BSL 3

Answer 36

Brucella suis, Mycobacterium tuberculosis

Question 37

List examples of BSL 4

Answer 37

Ebola virus, Small pox

Question 38

What has to happen for a microbe to cause disease? Also know as *Virulence Factors

Answer 38

``` Gain entry Enough population (minimal infectious dose) Adherence Overcome host defenses Damage host Exit host ```

Question 39

What bacteria was first found to have the characteristic of quorum sensing?

Answer 39

Vibrio fischeri

Question 40

What is the unique feature of Vibrio fischeri?

Answer 40

It is quorum sensing is shown through bio-luminescence. Only when it reaches a certain population does it become bio-luminescent.

Question 41

List the ways bacteria can cause damage.

Answer 41

Direct damage to host cell Using host's nutrients Produce toxins Induce hypersensitivity reactions

Question 42

What are some direct damage to the host cell?

Answer 42

Growth and replication in host cells: result in host cell lysis Penetration through host cells (mucosa organs) causes damage Lysis of host cells to obtain nutrients

Question 43

What ways can microorganisms use the host's nutrients?

Answer 43

By producing *siderophores that bind iron form host proteins and are then absorbed by the bacteria.

Question 44

Give an example of siderophores and what kind of bacteria is it usually found in?

Answer 44

Enterobactin found primary in Gram-negative

Question 45

Bacterial factors that disturb host functions

Answer 45

Protein *exotoxins Hydrolytic Enzymes Products that evoke aberrant host response

Question 46

*What are some products that evoke aberrant host response?

Answer 46

* Cross-reactive antigens (autoimmunity) * Superantigens * Endotoxin (Gram-negative)

Question 47

Describe endotoxin

Answer 47

LPS, Lipid A part: relase upon cell death; symptoms due to vigorous inflammination. Massive release: endotoxic shock.

Question 48

*Difference between endotoxin and exotoxin.

Answer 48

Exotoxin are proteins produced inside bacteria as part of growth and metabolism then secreted outside the cell. Endotoxins are lipid portions of LPSs that are part of the outer membrane in Gram-negative and are liberated when bacteria dies and cell wall breaks apart.

Question 49

*Poisonous substances produced by microorganisms are called

Answer 49

*Toxins

Question 50

*Toxemia refers to

Answer 50

*The presents of toxins in the blood

Question 51

*Ability to produce toxins is called

Answer 51

*Toxigenicity

Question 52

*T:F Exotoxins are not bacteria

Answer 52

*True | Exotoxins are produced by bacteria and cause disease symptoms.

Question 53

*Antibodies produced against exotoxins are called

Answer 53

*Antitoxins

Question 54

How are toxins named?

Answer 54

Named according to type of cell they attack

Question 55

What are the three basic types of exotoxin based on?

Answer 55

Structure and function

Question 56

What are the three basic types of exotoxin based on structure and function?

Answer 56

A-B toxins (type III) Membrane disrupting toxins (Type II) Superantigens (Type I)

Question 57

Descriptive terms that indicate site of some well defined protein toxins

Answer 57

Neurotoxins- attack neurons Leukotoxins- attack blood Enterotoxins- attack gastrointestinal Cytotoxins- attack cells

Question 58

What are the two components of the A-B Toxins and what do they do?

Answer 58

The A polypeptide is the *enzyme active and the B polypeptide is a *binding component. A subunit enzymatically kills the cell.

Question 59

Membrane disrupting toxins do what?

Answer 59

Type II toxins that disrupt host cell plasma membranes

Question 60

Superantigens do what?

Answer 60

Type I toxin: special type of exotoxin: nonspecifically stimulate T-cells. Cause intense immune response die to release of cytokines from host cells.

Question 61

Draw out Table 15.3

Answer 61

Refer to lecture 3 slide 30 BacT

Question 62

Draw out table 15.2 (Special attention to Botulism, diphtheria, clostridium perfringens, Food poisoning, Toxic shock syndrome)

Answer 62

Refer to lecture 3 slide 31 BacT

Question 63

How can bacteria acquire virulence factors?

Answer 63

* Encoded on chromosomal DNA | * Encoded on bacteriophage DNA, Plasmid DNA or Transposons

Question 64

Bacteriophages

Answer 64

Are virus particles which attack bacteria. | Phage can be transmitted to nonpathogenic strains making them virulent

Question 65

Lysogenic conversion with bacteriophages can?

Answer 65

Result in bacteria with virulence factors, such as toxins, fimbriae or capsules

Question 66

Bacteriophage genes

Answer 66

``` Corynebacterium diphtheria (Diphtheria toxin) Clostridium botulinum (Botulinum toxin) E. coli O157 H7( Shiga toxin) (haemolytic uremic syndrome) ```

Question 67

The process by which DNA is transferred form one bacterium to another by a virus is called

Answer 67

Transduction

Question 68

The process by which one bacterium (bacterium with a fertility factor) transfers genetic material to another through direct contact.

Answer 68

Conjugation

Question 69

The genetic alteration of a cell resulting form the direct uptake and incorporation of exogenous genetic material form surroundings and taking up through the cell membrane.

Answer 69

Transformation