Activities of Pathogens

Question 1

What are the differences between primary, principal and opportunistic pathogens?

Answer 1

Primary = when isolated always causes disease
Principal = causes infection in otherwise well people with intact defences
Opportunistic = causes disease when defences are down

Question 2

What are virulence factors?

Answer 2

The genetic determinants that allow bacteria to cause disease

Question 3

What are some examples of virulence factors?

Answer 3

Adherence
Invasion
Immune evasion
Toxins

Question 4

What are the two extremes on the virulence scale?

Answer 4

Never causes disease

Causes disease with no host defences down

Question 5

Describe gut flora

Answer 5

Anaerobic
E. coli/ enterococcus faecialis
help digest stuff

Question 6

What is a pyogenic infection?

Answer 6

Tissue invasion in a sterile site, causing inflammation and pus formation

Question 7

What is a granulomatous infection?

Answer 7

A granuloma is formed because innate immune system has been over run and adaptive immunity is required

Question 8

What are the two ways that bacteria can cause intoxication?

Answer 8

Intoxication by changing cell physiology (cholera)

Intoxication by damage (gangrene)

Question 9

How does bacteria cause immune mediation?

Answer 9

Antigen mimicry

Question 10

Describe the progression of appendicitis

Answer 10

Appendix becomes obstructed by a faecolith and bacteria propagate
Immune response occurs and appendix becomes inflamed. Once full of dead immune cells and dead bacteria this causes pain (begins at belly button but once parietal peritoneum is reached right lower quadrant)
Chronic inflammation causes appendiceal mass
Ruptures, peritonitis, sepsis, death

Question 11

Which final way can bacteria induce disease?

Answer 11

Cancer (helicobacter pylori)

Question 12

What is the pattern that pathogens follow while causing disease?

Answer 12

Get to host
Get to and recognise environment
Adhere/ interact and compete with other organisms/ host
Replicate
Be transmitted

Question 13

How does a pathogen achieve adherence?

Answer 13

Be viable in their environment
Be motile
Be transmitted to their niche
Use chemotaxis
Use host targets to bind

Question 14

How does competition with a host differ from competition with other organisms in an environment?

Answer 14

When competing with a host they must have a strategy to avoid the immune system
When competing with other organisms pathogens are fighting for nutrients and space

Question 15

How can a complement cascade affect pathogens?

Answer 15

Chemotaxis
Opsonisation
Can make holes in bacteria to increase recognition by immune cells

Question 16

What is streptococcus pyogenes?

Answer 16

Colonises pharynx in children
Causes pharyngitis and skin infection commonly
Rarely can cause rheumatic fever

Question 17

What are the symptoms of rheumatic fever?

Answer 17

Fever
Painful joints
Inflamed heart
Circular rash
Chorea

Question 18

What are the two ways that diseases are transmitted?

Answer 18

Direct: Sexual, fecal-oral, droplet, airborne
Indirect: Vector borne, health care worker, transfusion, airborne

Question 19

What are some precautions for preventing the spread of disease?

Answer 19

Waste management, environmental cleaning, disposal of sharps, gloves and gowns, masks, respirator masks and HAND HYGIENE

Question 20

What are the three ways to categorise diseases/ pathogens?

Answer 20

Structure
Disease (what it effects)
Transmission (arbovirus, enterovirus, respiratory virus)

Question 21

How do you diagnose a viral illness?

Answer 21

Serology (see if they have antibodies to it)
Clinical (symptoms)
Culture (grow it)
Visualisation
PCR

Question 22

Definitions of pathogen, infection, colonisation, infectious disease, endogenous disease, exogenous disease and zoonosis go!

Answer 22

Pathogen-microbe capable of causing disease
Infection- microbe established on host
Colonisation- infection with no overt immune response
Infectious disease- Interaction with a microbe that causes damage to the host
Endogenous- infection arising from colonising pathogen/flora
Exogenous-infection arising from other factors
Zoonosis-infectious disease from another animal host