Mechanisms of bacterial infection: pathogenesis I

Question 1

What are some local symptoms of inflammation?

Answer 1

• Redness
• Swelling
• Warmth
• Pain
• Loss of function

Question 2

What are some systemic symptoms of inflammation?

Answer 2

• Fever
• Rigors
• Chills
• Tachycardia
• Tachpnoea

Question 3

Mechanism of direct tissue damage:

Answer 3

• Increased blood flow
• Permeability to fluid
• Vascular endothelium is sticky
• Migration of phagocytes to site of infection

Question 4

What is an exotoxin?

exiting toxic relationship therefore it could be seen as what?

Answer 4

Proteins found in gram positive/negative

-seen as positive or negative 😌😢

Question 5

What is an endotoxin?

entering toxic relationship

Answer 5

Immunostimulants found in gram NEGATIVE

• seen as NEGATIVE
• released when bacteria is damaged

Question 6

Define toxins:

Answer 6

• promote adhesion of bacteria
• destroy cells
• interfere with cell metabolism
• affect nerves
• pore formation
• inhibit protein synthesis

Question 7

4 types of toxins:

Answer 7

• at cell membrane
• on cell membrane
• intacellular
• connective tissue

Question 8

What is endotoxic shock and sepsis?

Answer 8

• Endotoxins activate macrophages
• these release TNF/Platelet activating factors
• prostoglandins/leukotriens
• increased vascular permeability
• hypotension
• shck
• fever
• intravascular coagulation
• organ failure
• secretions of immunoglobulins
• sepsis (systemic inflammation response syndrome)

Question 9

What are bacterial enzymes?

Answer 9

• Break down hyaluronic acid

- allows bacteria and inflammatory exudate to travel further

Question 10

Examples of bacterial enzymes?

Answer 10

• protease
• lipase
• amylase
• nuclease

Question 11

Describe Toxic shock syndrome:

Answer 11

• Toxins produced from
• staphylococcus aureus/Staphylococcus pyogenes
• toxins act as super antigens (act with MHC2 antigens which activate macrophages/TNF/IFNy)
• activates all T cells

Question 12

Difference between humoral and cellular immunity

Answer 12

Humoral = antibodies produced

Cellular = T lymphocytes

Question 13

What is immune complex disease?

Answer 13

• host produces antibodies which bind to antigens to form immune complexes
• leads to hypersensitivity reaction

Question 14

What is molecular mimicry?

Answer 14

• antibodies cross-react with antigens of the host tissue such as myocardium/synovium/brain

Question 15

What is hypersensitivity?

Answer 15

T helper cells react to specific antigens,

• release cytokines,
• activate macrophages
• tissue damage.

Question 16

What are the different types of infections?

Answer 16

Local (surface infection)

invasive (penetrate barriers),

systemic (blood, lymphatics).

Question 17

What are the different types of virulence factors?

Answer 17

• Adherence (pili)
• Invasion (surface effector proteins)
• Capsules (protect from opsonisation)
• endotoxins (fever/inflammation)
• exotoxins (protein toxins/enzymes)
• siderophores (iron-binding)