Week 1: Models and Sepsis

Question 1

What is a pathogen?

Answer 1

A pathogen is a bacteria (in this context) capable of inducing damage either from toxins produced or by inducing a severe inflammatory response that is inappropriate and may eventually lead to cancer

Question 2

What is virulence?

Answer 2

Also known as pathogenicity, and it is the ability for a pathogen to cause infection, including:
- Infectivity/ ability to colonise and hold on
- Invasiveness/ ability to establish niche + multiply in the host
- Pathogenic potential/ the potential damage it could cause
It is multifactorial

Question 3

What is an infection?

Answer 3

When a pathogen becomes established in the body, and when it begins to cause symptoms it becomes known as a disease.

Question 4

Asymptomatic carrier/carriage

Answer 4

When the host’s defences are sufficient to have an infection/is infected but not have a disease over a prolonged period

Question 5

Steps in pathogenesis

Answer 5

1) Reservoir + transmission
2) Entry
3) Adhesion
4) Evasion of immune response
5) Adapting to the environment and multiplying
6) Damage
7) Dissemination + repetition

Question 6

Examples of models used to study infection

Answer 6

1) Primates (Extremely rare)
2) Other large mammals (Rare)
3) Rabbits
4) Rats
5) Mice
6) Fish
7) Insects
8) Plant material
9) Caenorhabditis elegans

Question 7

Potential problems with using models to study infection

Answer 7

• The bacteria may not naturally infect the subject
• A much higher dose may be required for the subject than for the natural host
• Subject may not have the appropriate response

Question 8

What is sepsis?

Answer 8

• The systematic inflammatory response to infection caused by any class of microorganism with the invasion of the microorganism or their toxins in the bloodstream causing illness
• A very serious clinical condition caused by innate immunity as a result of overstimulating the immune system
• > 50% mortality rate

Question 9

Symptoms of sepsis

Answer 9

Normal:
- Fever >38 degrees Celsius
- Chills
- Fast pulse
- Fast breathing
Sever instances:
- Dizziness
- Confusion/disorientation
- Nausea/vomiting

Question 10

Causes of sepsis

Answer 10

• Primary infections:
  + Pneumonia
  + Influenza
  + Appendicitis
  + Peritonitis
  + UTIs
  + Medical breaches of skin
  + Meningitis + encephalitis
• ~20% of cases are

Question 11

Causes of sepsis

Answer 11

• Primary infections:
  + Pneumonia
  + Influenza
  + Appendicitis
  + Peritonitis
  + UTIs
  + Medical breaches of skin
  + Meningitis + encephalitis
• ~20% of cases are idiopathic

Question 12

Stages of sepsis

Answer 12

• Uncomplicated sepsis: May be a result from an infection, can be treated without hospitalisation
• Severe sepsis: When the immune response has begun to interfere with organ function
• Septic shock: Results from severe sepsis, blood pressure drops to dangerous levels, tissues become hypoxic + begin to lose function