Unit 4.1: Microbial Mechanisms of Pathogenicity

Question 1

How bacterial pathogens penetrate host defenses?

_____
* Some microbes vary the expression of antigens, thus avoiding the host’s antibodies.

_____
* Bacteria may produce proteins that alter the actin of the host cell’s cytoskeleton, allowing bacteria into the cell.

Answer 1

Antigenic Variation
Penetration into the Host

Question 2

4 basic ways how bacterial pathogens damage host cells

Answer 2

1. Using the Host’s Nutrients: Siderophores
2. Direct Damage
3. By producing toxins
4. By inducing hypersensitivity reactions/Plasmids, Lysogeny, and Pathogenicity

Question 3

The Production of Toxins

_____: Poisonous substances produced by microorganisms.

_____: the presence of toxins in the blood.

_____: the ability to produce toxins.

_____: produced by bacteria (inside) and released into the surrounding medium.

_____: Altered exotoxins (as vaccine, stimulates antitoxin production).

_____: Antibodies produced against exotoxins

Answer 3

Toxins
Toxemia
Toxigenicity
Exotoxins
Toxoids
Antitoxins

Question 4

consist of an active component that inhibits a cellular process and a binding component that attaches the two portions to the target cell.

Answer 4

A-B toxins

Question 5

• cause cell lysis:
• forming protein channels in the plasma membrane.
• disrupt the phospholipid portion of the membrane.

Answer 5

Membrane-disrupting toxins

Question 6

• destroy erythrocytes (red blood cells)
• Forms protein channels

Answer 6

Hemolysins

Question 7

Antigens that provoke the release of cytokines (produced by host T cells):

• regulate immune response and mediate cell-to-cell communication.
• High levels cause fever, nausea, and other symptoms

Answer 7

Superantigens

Question 8

the lipid A component of the cell wall of gram-negative bacteria.

Answer 8

Endotoxin

Question 9

Endotoxins stimulate macrophages to release _____ in very high concentrations causing fever and shock (decrease in blood pressure).

Answer 9

cytokines

Question 10

_____ may carry genes for antibiotic resistance, toxins, capsules, and fimbriae.

Answer 10

Plasmids

Question 11

_____ can result in bacteria with virulence factors, such as toxins or capsules.

Answer 11

Lysogenic conversion

Question 12

Pathogens leave a host by portals of exit.

_____ via coughing or sneezing.
_____ via saliva or feces.
_____ via secretions from the vagina or penis.
_____ via drainage from wounds or by arthropods and syringes.

Answer 12

Respiratory tract
Gastrointestinal tract
Genitourinary tract
Blood

Question 13

Pathogenicity

Answer 13

Portals of entry

Penetration or evasion of host defenses

Damage to host cells

Portals of exit

Question 14

Portals of entry

mucous membranes
- _____
- _____
- _____
- _____

skin
- _____

Answer 14

Respiratory tract
Gastrointestinal tract
Genitourinary tract
Conjunctiva

Parenteral route

Question 15

Penetration or evasion of host defenses

Answer 15

Capsules
Cell wall components
Enzymes
Antigenic variation
Invasins
Intracellular growth

Question 16

Damage to host cells

Answer 16

Siderophores
Direct damage
Toxins
- Exotoxins
- Endotoxins
Lysogenic conversion
Cytophatic effects

Question 17

Portals of exit

Answer 17

Mucous membranes
Skin
Parenteral route